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Geotechnical and Foundation engineering Lab Manual
Geotechnical laboratory manual Page i
Geotechnical and Foundation
Engineering
Lab Manual
Produced by;
Engr.Saeedullah Jan Civil Engineering Department
BUITEMS, Quetta
Geotechnical and Foundation engineering Lab Manual
Balochistan University of of Information Technology Engineering & Management Sciences i (BUITEMS), Quetta
Practical Workbook
Geotechnical and Foundation Engineering
This is to certify that this practical workbook
contains 124 pages.
Chairman September 2012
Department of Civil Engineering Balochistan University of Information Technology
Engineering & Management Sciences, Quetta
Geotechnical and Foundation engineering Lab Manual
Balochistan University of of Information Technology Engineering & Management Sciences ii (BUITEMS), Quetta
THE IMPORTANCE OF GEOTECHNICAL LABORATORY TESTING Soil can exist as a naturally occurring material in its undisturbed state, or as a compacted material. Geotechnical engineering involves the understanding and prediction of the behavior of soil. Like other construction materials, soil possesses mechanical properties related to strength, compressibility, and permeability. It is important to quantify these properties to predict how soil will behave under field loading for the safe design of soil structures (e.g. embankments, dams, waste containment liners, highway base courses, etc.), as well as other structures that will overly the soil. Quantification of the mechanical properties of soil is performed in the laboratory using standardized laboratory tests.
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EE NN GG II NN EE EE RR II NN GG && MM AA NN AA GG EE MM EE NN TT SS CC II EE NN CC EE SS ,, QQ UU EE TT TT AA
Geotechnical and Foundation engineering Lab Manual
Balochistan University of of Information Technology Engineering & Management Sciences iii (BUITEMS), Quetta
CC OO NN TT EE NN TT SS
1 IN PLACE SOIL DENSITY USING SAND CONE METHOD 1
2 COEFFICIENT OF PERMEABILITY (CONSTANT HEAD METHOD) 11
3 COEFFICIENT OF PERMEABILITY (FALLING HEAD METHOD) 21
4 DIRECT SHEAR TEST 30
5 ONE DIMENSIONAL CONSOLIDATION TEST 42
6 STANDARD PENETRATION TEST 63
7 UNCONFINED COMPRESSION TEST 73
8 TRIAXIAL TEST 82
9 PLATE LOAD TEST 96
10 CALIFORNIA BEARING RATIO TEST 106
BIBLIOGRAPHY 118
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 1 (BUITEMS), Quetta
1 IN PLACE SOIL
DENSITY USING
SAND CONE
METHOD
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 2 (BUITEMS), Quetta
11 .. 11 II NN TT RR OO DD UU CC TT II OO NN
Basically, both the sand-cone and balloon-density methods use the same principle. That
is, one obtained a known weight of damp (or wet) soil from a small excavation of
somewhat irregular shape (a hole) in the ground. If one knows the volume of the hole, the
wet density is simply computed as
holeofvolume
soildampofweightwet
and if one obtained the water content w of the excavated material, the dry unit weight of
the material is
w1
wetdry
The sand cone method is an indirect means of obtaining the volume of the hole. The sand
used (often Ottawa sand) is generally material passing the No. 20 sieve but retained on
the No. 30 sieve. If one has a constant-density material of, say, 1.60 g/cm³ and pouring
4800 g of this material into an irregular-shaped hole, the volume of the hole can be found
by proportion as:
3
3
cm/g60.1
cm1
4800
V
material unit wt.of
hole fill toused material of wt.Vhole
11..11..11 DDEEFFIINNIITTIIOONNSS
BBUULLKK DDEENNSSIITTYY
Bulk density refers to the weight (mass) of soil per unit volume and the soils bulk density
is normally expressed in g cm-3
(weight divided by volume).
UUNNIITT WWEEIIGGHHTT
Unit weight is defined as weight per unit volume.
11 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT
The object of this test is to determine the dry density of natural or compacted soil, in-
place and its degree of compaction.
11 .. 33 SS CC OO PP EE OO FF TT EE SS TT
Once compaction criteria are established for the soil to be used at a particular site,
generally with both moisture and density limitations, some means of verification of the
results must be used. On all small projects and nearly all-large projects, this verification is
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 3 (BUITEMS), Quetta
achieved by either the sand-cone method or the balloon density method. On a few large,
nuclear devices have been and are considered further.
11 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE SS
ASTM: D 1556-64
AASHTO: T 191-61
11 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
The test equipment consists of:
1. Sand cone apparatus
2. Shovels (Digging tools)
3. Metal tray with a central circular hole of diameter equal to the diameter of the
pouring cone
4. Balance accurate to 1g
5. clean, uniformly graded sand ranging from #20 to #30 sieve such as Ottawa Sand
6. Paint brush to collect soil from template
7. Hammer and three nails to fix the metal tray on the spot
8. Spoon
9. plastic air tight bag for carrying wet excavated soil from field to laboratory
10. Oven with temperature kept at about 105-110oC
Figure 1.1 Sand-Cone Apparatus
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 4 (BUITEMS), Quetta
Figure 1.2 Ottawa sand
11 .. 66 PP RR EE PP AA RR AA TT II OO NN OO FF SS AA MM PP LL EE AA NN DD TT EE SS TT
SS PP EE CC II MM EE NN
Carefully collect a sample from undisturbed core of soil adjacent to the points of soil
moisture determination using the tins provided. Trim off excess soil and wrap core in
labeled polythene bag for transport to laboratory.
11 .. 77 AA DD JJ UU SS TT MM EE NN TT AA NN DD CC AA LL II BB RR AA TT II OO NN OO FF
II NN SS TT RR UU MM EE NN TT
Prior to determining the bulk density of the sand and prior to conducting density tests, the
technician is required to determine the weight of sand needed to fill the large cone of the
density apparatus and the accompanying base plate. This weight is determined to the
nearest 0.01 kilogram and is referred to as the Cone Correction. The density apparatus
and the base plate are required to remain together and not be interchanged with other
devices without recalculating the Cone Correction.
The procedure for determination of the Cone Correction is detailed in AASHTO T 191
and is summarized as follows:
1. Fill the apparatus with the calibration sand and record the weight to the nearest
0.01 lb
2. Place the base plate on a clean, level surface
3. Invert the apparatus onto the base plate and open the valve to allow the cone and
the base plate to fill with sand
4. When the sand stops flowing into the cone, shut the valve and weigh the apparatus
to the nearest 0.01 lb
5. The difference between the full weight of the apparatus and the final weight after
filling the cone is referred to as the Cone Correction.
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 5 (BUITEMS), Quetta
11 .. 88 TT EE SS TT PP RR OO CC EE DD UU RR EE
11..88..11 DDEETTEERRMMIINNAATTIIOONN OOFF MMAASSSS OOFF SSAANNDD FFIILLLLIINNGG TTHHEE CCOONNEE
1. Fill the clean closely graded sand in the sand-pouring cylinder up to a height of
1cm below the top. Determine the total mass/weight of Bottle + Cone +Sand (M1).
2. Open the valve and allow the sand to flow out. Close the valve when no further
movement of sand is observed. Lift the jar carefully. Weigh the sand collected on
the glass surface. Its mass (Mc) is the mass of sand filling the pouring cone. Or
remove the bottle and cone combination from the base plate, and determine its
mass (M2), thus the mass of sand to fill the cone can be determined as:
Mc = M1 –M2
Pour the sand back into the cylinder, to have the same constant mass.
11..88..22 DDEETTEERRMMIINNAATTIIOONN OOFF BBUULLKK DDEENNSSIITTYY OOFF SSAANNDD
1. Determine the volume of the calibrating container. It would be either mentioned
or can be by measuring the diameter or by filling it with water full to the top and
finding the mass of water, it is therefore
m V
For pure water normally the mass density can be taken as = 1g/cm3
2. Place the sand-pouring cylinder concentrically on the top of the calibrating
container. Open the shutter and permit the sand to run into the container. When
there is no further movement of sand, close the shutter. Remove the cylinder and
find its mass. Thus mass per unit volume will give the bulk density of the sand.
On other hand this can also be done by taking a proctor compaction mold and,
using a spoon, filling it with Ottawa sand. Avoid any vibration of other means of
compaction of the sand poured into the mould. When the mold is full, strike off
the top of the mould with the steel straight edge, determine the mass of the sand in
the mold. The bulk density of the Ottawa sand can be then be given as:
V
Md
Where
M = Mass of the sand filling the mould.
V = Volume of the mould (1/30 ft3)
d = Bulk density of the sand.
11..88..33 DDEETTEERRMMIINNAATTIIOONN OOFF DDRRYY DDEENNSSIITTYY OOFF SSOOIILL IINN--PPLLAACCEE
1. Expose about 45cm2 area of the soil to be tested and trim it down to level surface.
Keep the tray on the level surface and fix it by the help of nails in its position and
excavate a circular hole of approximately 10cm in diameter and 15 cm deep and
collect all the excavated soil in the tray. Find the mass of the excavated soil.
2. Remove the tray, and place the sand-pouring cylinder concentrically on the hole.
Open the shutter and permit the sand to run into the hole. Close the shutter when
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 6 (BUITEMS), Quetta
no further movement of the sand is seen. Remove the cylinder and determine it’s
mass.
3. Keep a representative sample of the excavated soil for water content
determination.
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Unit weight of soil g
Dry density
1d
11 .. 11 00 RR EE SS UU LL TT SS
The dry unit weight of the soil = _________g/cm3
Dry unit weight/ specific weight
1d
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This test is applied in the cases like embankment and pavement construction; and is
basically a quality control test where certain degree of compaction is required. This test
is also used in stability analysis of embankments and slopes, for the calculation of
pressure in underlying strata for settlement problems and also designs of underground
structures.
11 .. 11 22 PP RR EE CC AA UU TT II OO NN SS
1. The excavation during sand cone method should be as rapid as possible to
maintain the representative moisture content.
2. The field test holes may be quite small, thus the error multiple is largest is
absolutely essential that no soil be lost during excavation
3. The largest possible water content sample should be used to improve test
reliability.
4. When using the sand cone method avoid vibrating either the ground in the area or
the sand jug as this will introduce too much sand into the hole thus causing an
apparent increase in the hole’s volume.
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 7 (BUITEMS), Quetta
11 .. 11 33 SS AA MM PP LL EE PP RR OO BB LL EE MM
SOIL TESTING LABORATORY
FIELD UNIT WEIGHT-SAND CONE METHOD
Sample No. 15 Project No. SR 2828
Boring No. B-21 Location Newell, N.C
Depth of sample 3 ft
Description of Sample Reddish brown silty clay
Tested by John Doe Date 1/26/89
(A) Determination of mass of sand filling the cone
The total mass of Bottle + Cone +Sand before filling the cone (M1) 9098gm
The total mass of Bottle + Cone +Sand after filling the cone (M2) 7268gm
Mass of the sand filling the cone (Mc) = M1- M2 1830gm
(B) Determination of bulk density of sand
The volume of the calibrating container (V) 2305cm3
The mass of the sand in the mold/calibrating container (M3) 3400gm
The bulk density of the Ottawa sand V
M 3s 1.47 gm/cm
3
(C) Determination of dry density of soil in- place
The mass of the excavated wet soil M4 2658gm
The total mass of Bottle + Cone +Sand before filling the hole (M5) 9066gm
The total mass of Bottle + Cone +Sand after filling the hole (M6) 4980gm
Mass of the sand filling the hole (Mh) = M5- M6 – Mc 2256gm
Volume of hole
s
hh
MV
1535cm
3
Bulk density of soil sh
4
h
4
M
M or
V
M 1.73 gm/cm
3
Unit weight of soil g 16097 kg/cm3
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 8 (BUITEMS), Quetta
(D) Water content determination
Mass of can + wet soil M7 106.41 gm
Mass of can + dry soil M8 103.38 gm
Mass water Mw = M7 – M8 3.03 gm
Mass of can M9 15.35 gm
Mass of dry soil Md = M8 – M9 88.03 gm
Water content
dM
Mw 3044%
Dry density
1d
Dry unit weight/ specific weight
1d 1.672 gm/cm
3
Result
The dry unit weight of the soil = ______1.672___ gm/cm3
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 9 (BUITEMS), Quetta
SOIL TESTING LABORATORY
FIELD UNIT WEIGHT-SAND CONE METHOD
Sample No. Project No.
Boring No. Location
Depth of sample
Description of Sample
Tested by Date
(A) Determination of mass of sand filling the cone
The total mass of Bottle + Cone +Sand before filling the cone (M1)
The total mass of Bottle + Cone +Sand after filling the cone (M2)
Mass of the sand filling the cone (Mc) = M1- M2
(B) Determination of bulk density of sand
The volume of the calibrating container (V)
The mass of the sand in the mold/calibrating container (M3)
The bulk density of the Ottawa sand V
M 3s
(C) Determination of dry density of soil in- place
The mass of the excavated wet soil M4
The total mass of Bottle + Cone +Sand before filling the hole (M5)
The total mass of Bottle + Cone +Sand after filling the hole (M6)
Mass of the sand filling the hole (Mh) = M5- M6 – Mc
Volume of hole
s
hh
MV
Bulk density of soil sh
4
h
4
M
M or
V
M
Unit weight of soil g
In situ Density By sand Cone Method
Balochistan University of of Information Technology Engineering & Management Sciences 10 (BUITEMS), Quetta
(D) Water content determination
Mass of can + wet soil M7
Mass of can + dry soil M8
Mass water Mw = M7 – M8
Mass of can M9
Mass of dry soil Md = M8 – M9
Water content
dM
Mw
Dry density
1d
Dry unit weight/ specific weight
1d
Result
The dry unit weight of the soil = gm/cm3
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 11 (BUITEMS), Quetta
2
COEFFICIENT
OF
PERMEABILITY (Constant Head Method)
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 12 (BUITEMS), Quetta
22 .. 11 II NN TT RR OO DD UU CC TT II OO NN
In geotechnical engineering problems measuring the flow of water through the soil is a
very important consideration. Soil has pores due to inter-particle spaces (voids). The
interconnectivity of voids determines the permeability characteristics of soil. Thus, rock,
concrete, and other porous material may also be permeable (pervious). Materials such as
clays and silts in natural deposits have considerable porosity but are practically
impervious or have permeability significantly low (in comparison to sand or gravel).
The coefficient of permeability of soil is important in various aspects such as:
Determining the seepage through or beneath dams and levees and into water wells; in
stability analyses of hydraulic structures through evaluation of uplift or seepage forces;
and in regulating seepage control and design of seepage velocities to check erosion in
earthen structures
The other important applications are in estimation of ground water flow, percolation,
surface recharge and yield from wells.
22..11..11 DDEEFFIINNIITTIIOONNSS
PPEERRMMEEAABBIILLIITTYY
Permeability is the ease with which the water flows through a soil medium.
CCOOEEFFFFIICCIIEENNTT OOFF PPEERRMMEEAABBIILLIITTYY
The rate of flow under laminar flow conditions through a unit cross sectional are of
porous medium under unit hydraulic gradient is defined as coefficient of permeability.
22 .. 22 OO BB JJ EE CC TT II VV EE SS
To introduce a method of determining coefficient of permeability of a coarse-grained soil
by constant head method.
22 .. 33 SS CC OO PP EE
The test method measures the flow rate of water through a soil specimen of a known
gross cross-sectional area, applying constant head and using Darcy’s expression for
determining its permeability constant.
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ASTM D234-68
AASHTO T215-66
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 13 (BUITEMS), Quetta
22 .. 55 AA PP PP AA RR AA TT UU SS
1. Permeability device (Permeameter)
2. Constant head tank
3. Thermometer, range 0 to 50oC, accurate to 0.1
oC
4. Stop watch.
5. Graduated cylinder.
6. De-aired distilled water
7. Coarse-grained soils
22 .. 66 TT EE SS TT PP RR OO CC EE DD UU RR EE
1. Measure the initial mass of the pan along with the dry soil (M1).
2. Remove the cap and upper chamber of the Permeameter by unscrewing the
knurled cap nuts and lifting them off the tie rods.
3. Measure the inside diameter of upper and lower chambers. Calculate the average
inside diameter of the Permeameter (D).
4. Place one porous stone on the inner support ring in the base of the chamber then
place a filter paper on top of the porous stone.
5. Mix the soil with a sufficient quantity of distilled water to prevent the segregation
of particle sizes during placement into the Permeameter.
6. Enough water should be added so that the mixture may flow freely.
7. Using a scoop, pour the prepared soil into the lower chamber using a circular
motion to fill it to a depth of 1.5 cm. A uniform layer should be formed.
8. Use the tamping device to compact the layer of soil. Use approximately ten rams
of the tamper per layer and provide uniform coverage of the soil surface. Repeat
the compaction procedure until the soil is within 2 cm. of the top of the lower
chamber section.
9. Replace the upper chamber section, and don’t forget the rubber
Figure 2.1 constant head assembly
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 14 (BUITEMS), Quetta
10. Gasket that goes between the chamber sections. Be careful not to disturb the soil
that has already been compacted. Continue the placement operation until the level
of the soil is about 2 cm. below the rim of the upper chamber.
11. Level the top surface of the soil and place a filter paper and then the porous stone
on it.
12. Place the compression spring on the porous stone and replace the chamber cap and
its sealing gasket. Secure the cap firmly with the cap nuts.
13. Measure the sample length at four locations around the circumference of the
Permeameter and compute the average length. Record it as the sample length.
14. Keep the pan with remaining soil in the drying oven.
15. Adjust the level of the funnel to allow the constant water level in it to remain a
few inches above the top of the soil.
16. Connect the flexible tube from the tail of the funnel to the bottom outlet of the
Permeameter and keep the valves on the top of the Permeameter open.
17. Place tubing from the top outlet to the sink to collect any water that may come
out. Open the bottom valve and allow the water to flow into the Permeameter.
18. As soon as the water begins to flow out of the top control (de-airing) valve, close
the control valve, letting water flow out of the outlet for some time.
19. Close the bottom outlet valve and disconnect the tubing at the bottom.
20. Connect the funnel tubing to the top side port. Open the bottom outlet valve and
raise the funnel to a convenient height to get a reasonable steady flow of water.
21. Allow adequate time for the flow pattern to stabilize.
22. Measure the time it takes to fill a volume of 750 - 1000 ml using the graduated
cylinder, and then measure the temperature of the water.
23. Repeat this process three times and compute the average time, average volume,
and average temperature. Record the values as t, Q, and T, respectively.
Figure 2.2 Half assembled permeameter.
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 15 (BUITEMS), Quetta
24. Measure the vertical distance between the funnel head level and the chamber
outflow level, and record the distance as h.
25. Repeat step 17 and 18 with different vertical distances.
26. Remove the pan from the drying oven and measure the final mass of the pan along
with the dry soil (M2).
22 .. 77 CC AA LL CC UU LL AA TT II OO NN SS
Using Bowles apparatus for determination permeability coefficient by measuring flow
through soil under a constant head is calculated from the following equation
ChtA
QLk
Where;
Q = quantity of flow, cm3 or ml
L = length of the sample, cm
h = applied head (constant) cm
t = time interval seconds
A = cross-sectional area of the sample cm2
C = Temperature correction for viscosity of water at 20C
Result
The coefficient of permeability of the given coarse-grained soil by Constant Head
Permeability test is found to be, k =___________________cm/s.
Soil Coefficient. of Perm., k,
cm/sec Degree of Permeability
Gravel >10-1 Very high
Sandy gravel, clean sand, fine
sand
10-1 > k > 10-3 High to Medium
Sand, dirty sand, silty sand 10-3 > k > 10-5 Low
Silt, silty clay 10-5 > k > 10-7 Very low
Clay <10-7 Virtually impermeable
Table 2.1 soil permeability properties
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The important applications of permeability are in estimation of ground water flow,
percolation, surface recharge and yield from wells
In the design of geotechnical engineering projects, one of the most important soil
properties of interest to the soils engineer is permeability. To some degree, permeability
will play a role in the design of almost any structure. For example, the durability of
concrete is related to its permeability. In designs that make use of earthen materials (soils
and rock, etc.)The permeability of these materials will usually be of great importance.
To illustrate the importance of permeability in geotechnical design, consider the
following applications where knowledge of permeability is required.
Permeability influences the rate of settlement of a saturated soil under load.
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 16 (BUITEMS), Quetta
The rate of flow to wells from an aquifer is dependent on permeability.
The design of earth dams is very much based upon the permeability of the soils used.
The performance of landfill liners is based upon their permeability.
The stability of slopes and retaining structures can be greatly affected by the permeability
of the soils involved.
Filters to prevent piping and erosion are designed based upon their permeability.
Soils are permeable (water may flow through them) because they consist not only of
solid, but a network of interconnected pores. The degree to which soils are permeable
depends upon a number of factors, such as soil type, grain size distribution and soil
history. This degree of permeability is characterized by the coefficient of permeability.
22 .. 99 PP RR EE CC AA UU TT II OO NN SS
1. The head may be varying.
2. The temperature should be constant
3. Be careful not to jar or bump the apparatus at all.
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 17 (BUITEMS), Quetta
22 .. 11 00 SS AA MM PP LL EE PP RR OO BB LL EE MM
SOIL TESTING LABORATORY
CONSTANT HEAD PERMEABILITY TEST
Description of soil Brown, medium coarse sand
Sample No. 2 Location soil laboratory
Unit Weight Determination
length between manometer outlets, L (cm) 11.43
Diameter of soil specimen, D (cm) 10.16
Cross sectional area of soil specimen A (cm2) (i.e. D
2/4) 81.0837088
Height H1 ,(cm) 20
Height H2 ,(cm) 4.5
Height of specimen (cm) (H1-H2) 15.5
Volume of specimen (cm3) 1256.797486
weight of air dried soil before compaction, W1 (g) 3200
Weight of unused remaining portion of soil after compaction, W2 (g) 1102.5
Weight of soil specimen (air dried) (g) 2097.5
Unit weight of soil specimen (air dried ) (lb/ft3) 104.140883
Water Content of Soil Specimen (air dried) (%) 1.100079428
can no. 2-A
weight of air dried soil + can 308.17
weight of oven dried soil + can 305.4
weight of can 53.6
water content of air dried soil (%) 1.100079428
Dry unit weight of soil specimen (lb/ft3) 103.0077163
specific gravity of soil 2.71
Volume of solids (ft3) 0.60913826
Volume of voids (ft3) 0.39086174
Void ratio e, of soil specimen 0.641663421
Permeability Test
length between manometer outlets, L (cm) 11.43
Cross sectional area of soil specimen A (cm2) 81.0837088
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 18 (BUITEMS), Quetta
Result
The coefficient of permeability of the given coarse-grained soil by Constant Head Permeability test is found to be,
k =_0.0918__cm/s.
Test
No.
Average
flow,
Q
(cm3)
Time of
collection
t
(sec)
Temperatu
re of water,
T
(oC)
Manometer Readings Head
difference,
h
(cm)
ChtA
QLk
(cm/sec)
Ratio of viscosity at
ToC/Viscosity at
20oC
Permeability at
20oC,
k20
(cm/s)
h1
(cm)
h2
(cm)
1 250 65 23 10.9 5.4 5.5 0.0986 0.9311 0.091785
2 250 63 24 10.9 5.4 5.5 0.1017 0.9097 0.092523
3 250 64 24 10.9 5.4 5.5 0.1001 0.9097 0.091077
4
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 19 (BUITEMS), Quetta
SOIL TESTING LABORATORY
CONSTANT HEAD PERMEABILITY TEST
Description of soil
Sample No. Location
Unit Weight Determination
length between manometer outlets, L (cm)
Diameter of soil specimen, D (cm)
Cross sectional area of soil specimen A (cm2) (i.e. D
2/4)
Height H1 ,(cm)
Height H2 ,(cm)
Height of specimen (cm) (H1-H2)
Volume of specimen (cm3)
weight of air dried soil before compaction, W1 (g)
Weight of unused remaining portion of soil after compaction, W2 (g)
Weight of soil specimen (air dried) (g)
Unit weight of soil specimen (air dried ) (lb/ft3)
Water Content of Soil Specimen (air dried) (%)
can no.
weight of air dried soil + can
weight of oven dried soil + can
weight of can
Water content of air dried soil (%)
Dry unit weight of soil specimen (lb/ft3)
specific gravity of soil
Volume of solids (ft3)
Volume of voids (ft3)
Void ratio e, of soil specimen
Permeability Test
length between manometer outlets, L (cm)
Cross sectional area of soil specimen A (cm2)
Coefficient Of Permeability by Constant Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 20 (BUITEMS), Quetta
Result
The coefficient of permeability of the given coarse-grained soil by Constant Head Permeability test is found to be, k
=___________________cm/s.
Test
No.
Average
flow,
Q
(cm3)
Time of
collection
t
(sec)
Temperatur
e of water,
T
(oC)
Manometer Readings Head
difference,
h
(cm)
ChtA
QLk
(cm/sec)
Ratio of viscosity at
ToC/Viscosity at 20
oC
Permeabili
ty at 20oC,
k20
(cm/s) h1
(cm)
h2
(cm)
1
2
3
4
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 21 (BUITEMS), Quetta
3
COEFFICIENT
OF
PERMEABILITY (Falling Head Method)
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 22 (BUITEMS), Quetta
33 .. 11 II NN TT RR OO DD UU CC TT II OO NN
Fine soils such as silt and clay have considerable low permeability, which makes
determination of their permeability constant practically impossible when using constant
head test. Hence alternate method is suggested which measures the flow of water through
soil sample by applying variable head that decreases with time as the level of water above
the soil samples decreases (falling head). The drop in the level is of water in a known
time is measured for calculating the coefficient of permeability.
33..11..11 DDEEFFIINNIITTIIOONNSS
PPEERRMMEEAABBIILLIITTYY
Permeability is the ease with which the water flows through a soil medium.
33 .. 22 OO BB JJ EE CC TT II VV EE SS
To determine the coefficient of permeability of a fine grained soil by falling head method
such as fine sand, silt, or clay. This test may also be used for coarse grained soils.
33 .. 33 SS CC OO PP EE
The test method is applicable to fine-grained soils through which rate of flow of water is
measured keeping known gross cross-sectional area constant while the applied head
(hydraulic potential) decreases gradually with time. This test determines the permeability
of sample that has permeability less than about 10-3
cm/s (less permeable soil).
33 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE
ASTM D234-68
AASHTO T215-66
33 .. 55 AA PP PP AA RR AA TT UU SS
1. Falling Head Permeability device (Permeameter).
2. Thermometer.
3. Stop watch.
4. Graduated cylinder.
5. Fine grained material
6. Ring stand with test-tube clamp or other means to develop a differential head
across soil sample.
7. Burette with stand.
8. Electronic balance (LC = 0.1g)
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 23 (BUITEMS), Quetta
33 .. 66 PP RR OO CC EE DD UU RR EE
1. Weigh the Permeameter mold with the base plate and porous stone attached. Also
measure the inside mold diameter and height in order to calculate the cross-
sectional area and sample length, as well as the cross-sectional area of the burette,
which can be determined from the distance between graduations.
2. Fill the mold with the soil sample by a method appropriate to the material and
purpose of testing.
3. For tests on loose cohesion less soils: Assemble the Permeameter base and mold,
then using a large funnel let the dry cohesion less soil rain into the mold at a
constant rate. The funnel should be kept about one inch above the soil surface and
continuously moved in a spiral motion allowing the sand to accumulate uniformly.
An oven-dry moisture determination (AASHTO T 265) shall be made in order to
compute the dry density of the soil.
4. For tests on compacted soils: Using the Permeameter molds, embankment type
materials are compacted in accordance with AASHTO T-99, Method C, while
base and stabilized sub grade type materials are compacted in accordance with
AASHTO T 180. After compaction, the mold is removed from the compaction
base and assembled in the Permeameter base.
5. Weigh the assembled mold and base plate with soil and determine the density of
dry soil. Measure the length of the soil sample L. If material is loose, the length of
the soil sample should be measured before and after the permeability tests to
determine any change in length due to consolidation of soil. The final value of L is
used for computations of K.
6. Place a piece of filter paper on top and bottom of the sample, then place the
perforated disc. Making sure the rim is clean, place the gasket and seat the cover.
7. Using a vacuum pump or suitable aspirator, (Fig. 1) evacuate the specimen a
minimum of 15 minutes to remove air adhering to soil particles and from the voids
(Note 1). Follow the evacuation by a slow saturation of the specimen from the
Figure 3.1 Assembled falling head apparatus
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 24 (BUITEMS), Quetta
bottom upward, under vacuum, in order to free any remaining air in the specimen.
De-aired water is recommended for the saturation of the specimen. The water
supply should be slightly elevated in order to produce a small hydraulic head
during saturation.
8. Note 1: A maximum vacuum of 250 mm (10 in.) mercury is recommended. Some
sandy soils with permeability greater than 10-³ should not be subjected to a
vacuum greater than 125 mm (5 in.) mercury. In no case shall a combination of
vacuum and hydraulic head be great enough to produce turbulent flow in the
specimen during saturation.
9. After the specimen has been saturated and the Permeameter is full of water,
partially close the valve on the outlet tube to produce a minimum steady state flow
at the inlet, and then disconnect the vacuum.
10. Immediately attach the Permeameter to the rubber tube at the base of the burette.
The burette and the rubber tube should already be filled and flowing with water
from a supply, which has been temperature stabilized and de aired. The
Permeameter should now be free of air bubbles.
11. Close the outlet valve and fill the burette to a convenient height.
12. Remember that the inlet valve is partially open and should be completely opened
at this point. Measure the hydraulic head across the sample to obtain ho.
13. Disconnect the outlet tube from the saturation reservoir and place it in a filled
container.
14. Open the outlet valve and simultaneously start timing the test. Allow water to flow
through the sample until the burette is almost empty.
15. Simultaneously record the elapsed time and clamp only the outlet tube. Measure
the hydraulic head across the sample at this time to obtain h1. Take the
temperature of the test.
16. Refill the burette and repeat step Section 4.9 two additional times.
17. Take the temperature each time.
18. Compute the coefficients of permeability at the test temperature, kt, for each trial,
and k at 20°C using the correction values from table 1.
19. Average all three or the two closest values for k = 20.
33 .. 77 CC AA LL CC UU LL AA TT II OO NN SS
The coefficient of permeability is calculated from the following equation,
Ch
h
At
aLk
2
1ln
Where,
a = cross-sectional area of burette cm2
L = length of the sample cm
h1 = Initial hydraulic head cm
h2 = Final hydraulic head cm
t = time interval seconds
A = cross-sectional area of the soil sample cm2
C = Temperature correction for viscosity of water at 20C.
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 25 (BUITEMS), Quetta
33 .. 88 RR EE SS UU LL TT SS
The coefficient of permeability of the given fine-grained soil by Falling Head
Permeability test is found to be, k =___________________cm/s.
33 .. 99 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS
Practical uses of falling head permeability test are 1. Settlements in structures
2. Methods for lowering the ground water table during construction
3. Design grouting pressures and quantities for soil stabilization
4. Freeze Thaw movements in soils (Note that coefficient of permeability ( k) varies
with temperature
5. as the viscosity of the fluids changes with temperature)
6. Design of recharge pits
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 26 (BUITEMS), Quetta
33 .. 11 00 SS AA MM PP LL EE PP RR OO BB LL EE MM
SOIL TESTING LABORATORY
FALLING HEAD PERMEABILITY TEST
Description of soil Brown, medium coarse sand
Sample No. 2 Location Soil laboratory
Unit Weight Determination
Weight of Permeameter (mold) with the base plate and
gasket attached + soil (g) 3401.1
Weight of empty Permeameter (mold) with the base plate
and gasket attached (g) 1098.5
Weight of soil specimen (g) 2302.6
Diameter of soil specimen, D (i.e., inside dia of mold)(cm) 10.16
Cross sectional area of soil specimen(ie 3.142*D2/4) 81.0837088
Length of soil specimen in Permeameter, L (cm) 15.8
volume of soil specimen 1281.122599
Unit weight of soil specimen (air dried) 112.1533881
Water content of soil specimen (air dried) (%) 1.100079428
can no. 2-A
weight of air dried soil + can 308.17
weight of oven dried soil + can 305.4
weight of can 53.6
Water content of soil specimen (air dried) (%) 1.100079428
Dry unit weight of soil specimen (lb/ft3) 110.9330365
Specific gravity of soil 2.71
Volume of solids 0.656004805
Volume of voids 0.343995195
Void ratio, e, of soil specimen 0.524379078
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 27 (BUITEMS), Quetta
Test
No.
h1
(cm)
h2
(cm)
Test
duration,
t
(sec)
Temperature
of water,
T
(oC)
permeability
at T (oC),
KT
(cm/s)
Ratio of
viscosity at
ToC/Viscosity
at 20oC
Permeability at
20oC,
k20
(cm/s)
1 150 20 32.3 22 0.022223465 0.9531 0.02118
2 150 20 32.6 22 0.022018955 0.9531 0.02099
3 150 20 31.7 22 0.022644099 0.9531 0.02158
Calculation
The coefficient of permeability is calculated from the following equation,
Ch
h
At
aLk
2
1ln
Result
The coefficient of permeability of the given fine-grained soil by Falling Head
Permeability test is found to be, k20 oC =________0.06375___________cm/s.
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 28 (BUITEMS), Quetta
SOIL TESTING LABORATORY
FALLING HEAD PERMEABILITY TEST
Description of soil
Sample No. Location
Unit Weight Determination
Weight of permeameter (mold) with the base plate and gasket attached + soil (g)
Weight of empty permeameter (mold) with the base plate and gasket attached (g)
Weight of soil specimen (g)
Diameter of soil specimen, D (ie inside dia. of mold)(cm)
Cross sectional area of soil specimen(ie 3.142*D2/4)
Length of soil specimen in permeameter, L (cm)
volume of soil specimen
Unit weight of soil specimen (air dried)
water content of soil specimen(air dried) (%)
can no.
weight of air dried soil + can
weight of oven dried soil + can
weight of can
water content of soil specimen(air dried) (%)
Dry unit weight of soil specimen (lb/ft3)
Specific gravity of soil
Volume of solids
Volume of voids
Void ratio, e, of soil specimen
Coefficient Of Permeability by Falling Head Method
Balochistan University of of Information Technology Engineering & Management Sciences 29 (BUITEMS), Quetta
Test
No.
h1
(cm)
h2
(cm)
Test
duration,
t
(sec)
Temperature
of water,
T
(oC)
permeability
at T (oC),
KT
(cm/s)
Ratio of
viscosity at
ToC/Viscosity
at 20oC
Permeability at
20oC,
k20
(cm/s)
1
2
3
4
Calculation
The coefficient of permeability is calculated from the following equation,
Ch
h
At
aLk
2
1ln
Result
The coefficient of permeability of the given fine-grained soil by Falling Head
Permeability test is found to be, k20 oC =________ __________cm/s.
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 30 (BUITEMS), Quetta
4 DIRECT SHEAR
TEST
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 31 (BUITEMS), Quetta
44 .. 11 II NN TT RR OO DD UU CC TT II OO NN
Shear strength may be estimated by measuring the resistance offered against sliding friction
at the interface of two surfaces or layers within granular materials. According to Mohr-
Coulomb theory a soil will fail at shear stress greater than or equal to
= c + tan
This can be represented graphically by developing failure envelope(s) named after Mohr and
Coulomb.
Where,
= shear stress
c = cohesion
= Angle of internal friction
= Normal or vertical stress
Chart 4.1 Normal Stresses vs. Shear Stress
Direct shear test used to be much popular in geotechnical investigations but now is not being
used extensively as more precise and reliable shear measurement techniques (Triaxial tests)
have been developed and introduced as standard methods. The other reasons for limited use
of direct shear test are:
1. The area of the sample changes as the test progresses, but may not be very significant
as most samples fail at low deformations.
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 32 (BUITEMS), Quetta
2. The actual failure surface is not plane, as is assumed or as was intended the way shear
box was designed, nor is the shearing stress uniformly distributed over the failure
surface, as is assumed when performing calculations.
3. The test uses a small sample that makes test susceptible to errors when preparing
specimen (i.e. difficult to obtain a representative sample).
4. The size of the sample precludes much investigation into pore water during the test
(drained and undrained conditions)
5. Values of the modulus of the elasticity and Poisson’s ratio cannot be determined.
44..11..11 DDEEFFIINNIITTIIOONNSS
RREELLAATTIIVVEE LLAATTEERRAALL DDIISSPPLLAACCEEMMEENNTT
Relative lateral displacement – the horizontal displacement of the top and bottom shear box
halves relative to each other.
FFAAIILLUURREE
The stress condition at failure for a test specimen. Failure corresponds to the maximum shear
stress attained or the shear stress at 15-20 percent relative lateral displacement. Depending on
soil behavior and field application, other suitable criteria may be defined.
SSHHEEAARR SSTTRREENNGGTTHH
Maximum shear stress that can be sustained by a material before rupture is called shear
strength. It is the ultimate strength of a material subjected to shear loading.
CCOOHHEESSIIOONN
It is the soils inter-particle attraction which ultimately provides resistance to sliding of
particles one over the other.
44 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT
This experiment is used to determine the internal angle of friction for a fine, dry sand by
means of a shear box apparatus.
44 .. 33 SS CC OO PP EE OO FF TT EE SS TT
Direct shear test is used to predict the value of the angle of internal friction and cohesion of
the soil parameters quickly. The laboratory report covers the laboratory procedures for
determining these values for cohesion less soils.
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 33 (BUITEMS), Quetta
44 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE
ASTM D3080-72
44 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
1. Direct shear box apparatus
2. Loading frame (motor attached).
3. Dial gauge.
4. Proving ring.
5. Tamper.
6. Straight edge.
7. Balance to weigh up to 200 mg.
8. Aluminum container.
9. Spatula.
Figure 4.1 Direct shear devices and shear box
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 34 (BUITEMS), Quetta
44 .. 66 PP RR EE PP AA RR AA TT II OO NN OO FF SS AA MM PP LL EE SS AA NN DD TT EE SS TT SS PP EE CC II MM EE NN
Test specimen can be prepared by mixing water in sand and carefully put it in mould in
layers with the help of wooden tamper.
44 .. 77 TT EE SS TT PP RR OO CC EE DD UU RR EE
1. Check the inner dimension of the soil container.
2. Put the parts of the soil container together.
3. Calculate the volume of the container. Weigh the container.
4. Place the soil in smooth layers (approximately 10 mm thick). If a dense sample is
desired tamp the soil.
5. Weigh the soil container, the difference of these two is the weight of the soil.
Calculate the density of the soil.
6. Make the surface of the soil plane.
7. Put the upper grating on stone and loading block on top of soil.
8. Measure the thickness of soil specimen.
9. Apply the desired normal load.
10. Remove the shear pin.
11. Attach the dial gauge which measures the change of volume.
12. Record the initial reading of the dial gauge and calibration values.
13. Before proceeding to test check all adjustments to see that there is no connection
between two parts except sand/soil.
14. Start the motor. Take the reading of the shear force and record the reading.
15. Take volume change readings till failure.
16. Add 5 kg normal stress 0.5 kg/cm2 and continue the experiment till failure
17. Record carefully all the readings. Set the dial gauges zero, before starting the
experiment
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 35 (BUITEMS), Quetta
44 .. 88 CC AA LL CC UU LL AA TT II OO NN SS
1. Compute the shear stress as τ = Ph / A
2. Compute the normal stress as σn = Pv / A
3. Compute the horizontal displacement, δh, and the vertical displacement, δv, for each
observed value.
4. Plot shearing stress against horizontal displacement and obtain the maximum value of
shearing stress, τmax.
5. Plot a graph of normal displacement vs. shear displacement. This should be on the
same page (same horizontal scale) as the shearing stress vs. shear displacement plot.
6. Using data from all three groups plot shearing stress against normal stress and show
the angle of internal friction, φ, and the intercept, c.
44 .. 99 RR EE SS UU LL TT SS
The shear strength parameters of the given soil sample tested in the laboratory are
c = kg/cm2,
= degree
Figure 4.2 Cross-section of a direct shear box test
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 36 (BUITEMS), Quetta
Plot a graph of Shear Stress vs. Normal Stress. This graph will be approximately a straight
line. The y-intercept of this line gives the cohesion. And the angle of internal friction of the
soil can be determined from the slope of the straight-line. For purely cohesion less soil this
line passes through origin.
n
tan 1
44 .. 11 00 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS
Near any geotechnical construction (e.g. slopes, excavations, tunnels and foundations) there
will be both mean and normal stresses and shear stresses. The mean or normal stresses cause
volume change due to compression or consolidation. The shear stresses prevent collapse and
help to support the geotechnical structure. Failure will occur when the shear stress exceeds
the limiting shear stress (strength). The evaluation of shear parameters is quite important
before initiating any geotechnical construction.
In many engineering problems such as design of foundation, retaining walls, slab bridges,
pipes, sheet piling, the value of the angle of internal friction and cohesion of the soil involved
are required for the design. Direct shear test is used to predict these parameters quickly. The
laboratory report covers the laboratory procedures for determining these values for cohesion
less soils.
44 .. 11 11 PP RR EE CC AA UU TT II OO NN SS
1. Preparation of sample should be carried out properly.
2. Sample must be placed in the mould carefully.
3. Each time mould should be properly cleaned with brush.
4. Care should be taken in handling the apparatus.
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 37 (BUITEMS), Quetta
44 .. 11 22 SS AA MM PP LL EE PP RR OO BB LL EE MM
GENERAL REPORT
DIRECT SHEAR TEST ON SAND
Client Name ________________________
Company Name _____________________
Project Name _______________________
Project No. _________________________
Location of site _____________________
Date of sampling ____________________
Date of testing ______________________
Reporting Name ____________________
Weight of specimen, W ___25 gm______
Normal load, N _____________________
Sample No.___15____________________
Boring No. ______________B-21_______
Depth of sample ___________3 ft_______
Description of Sample Reddish Brown Clay
Tested by __________________________
Comments _________________________
Location ___________________________
Date ______________________________
Normal stress, n ___________________
Proving ring calibration factor __0.15____
Horizontal
Displacement
(1)
Vertical
Displacement
(2)
No. of divisions
in proving ring
dial gauge
(3)
Shear
Force,
S
(4)
Shear stress,
(5)
20 200.152.2
= 6.6 0.264
60 19.8 0.792
135 44.55 1.782
CALCULATIONS
RESULTS
Graph
Plot a graph of shear stress vs. strain; determine the peak stress from the graph, If 20% strain
occurs before the peak stress, then the stress corresponding to 20% strain should be taken as
Shear strength and not the peak shear strength.
Plot a graph of Shear Stress vs. Normal Stress. This graph will be approximately a straight
line. The y-intercept of this line gives the cohesion. And the angle of internal friction of the
soil can be determined from the slope of the straight-line. For purely cohesion less soil this
line passes through origin.
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 38 (BUITEMS), Quetta
n
tan 1
Result
C = (kg/cm2)
=
0
50
100
150
200
250
300
0 5 10 15
Shea
r st
ress
,
(kg/c
m2)
Normal stress n, (kg/cm2)
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 39 (BUITEMS), Quetta
GENERAL REPORT
DIRECT SHEAR TEST ON SAND
Client Name ________________________
Company Name _____________________
Project Name _______________________
Project No. _________________________
Location of site _____________________
Date of sampling ____________________
Date of testing ______________________
Reporting Name ____________________
Weight of specimen, W ______________
Normal load, N _____________________
Sample No._________________________
Boring No. _________________________
Depth of sample _____________________
Description of Sample ________________
Tested by __________________________
Comments _________________________
Location ___________________________
Date ______________________________
Normal stress, ‘ ___________________
Proving ring calibration factor __________
Horizontal
Displacement
(1)
Vertical
Displacement
(2)
No. of
divisions in
proving ring
dial gauge
(3)
Shear
Force,
S
(4)
Shear stress,
(5)
CALCULATIONS
RESULTS
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 40 (BUITEMS), Quetta
Displacement
D/R
Horizontal
displacement
D/R × L.C
Corrected area A0=A-B×∆H
Load
D/R
Load S.F=D/R×L.C
shear stress
τ =S.F/A0
Direct Shear Test
Balochistan University of of Information Technology Engineering & Management Sciences 41 (BUITEMS), Quetta
Graph
Plot a graph of Shear Stress vs. Normal Stress. This graph will be approximately a straight
line. The y-intercept of this line gives the cohesion. And the angle of internal friction of the
soil can be determined from the slope of the straight-line. For purely cohesion less soil this
line passes through origin.
n
tan 1
Result
C = (kg/cm2)
=
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 42 (BUITEMS), Quetta
5 ONE
DIMENSIONAL
CONSOLIDATION
TEST
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 43 (BUITEMS), Quetta
55 .. 11 II NN TT RR OO DD UU CC TT II OO NN
This test method covers procedures for determining the magnitude and rate of consolidation
of soil when it is restrained laterally and drained axially while subjected to incrementally
applied controlled-stress loading.
This test method is most commonly performed on undisturbed samples of fine grained soils
naturally sedimented in water, however, the basic test procedure is applicable, as well, to
specimens of compacted soils and undisturbed samples of soils formed by other processes
such as weathering or chemical alteration. Evaluation techniques specified in this test method
are generally applicable to soils naturally sedimented in water. Tests performed on other soils
such as compacted and residual (weathered or chemically altered) soils may require special
evaluation techniques.
In case of consolidation settlement of a soil two issues are important i.e. (i) How much the
soil will settle under the application of a particular load and (ii) How long will it take in
settlement. For the latter one it is necessary to know the coefficient of consolidation Cv. To
determine Cv two approaches can be used, one the coefficient of permeability of a soil k, and
the coefficient of volume compressibility mv are known first, then by using
wv
vm
kC
,
where
w is unit weight of water at an ambient temperature.
Plot a graph between Deformations versus Time; the time at different degrees of
consolidation is obtained and by using
t
HTC drv
v
2
the value of Cv for a particular tested soil can be determined.
Where
Tv = Dimensionless time factor
60%U0for 1004
2
UTv
Tv = 1.78 - .933 log (100 – U) For U > 60
U = Degree of Consolidation
Charts are also available for different values of Tv against respective values of
U.
d = Length of the longest drainage path in the soil sample.
22
1 fi
dr
HHH
Hi = Initial sample thickness
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 44 (BUITEMS), Quetta
Hf = Sample thickness at complete consolidation under a Particular load
t = Time of interest obtained from deformation v/s. time curves.
In square root method where the graph is plotted between dial gauge reading
and square root of t , t 90 is used.
In logarithm method where graph is plotted between dial gauge reading and
Log (t), t50 is used.
In equation (i) the value T is put according to the value of t. If t = tu, then
T = TU. Where, U shows degree of consolidation
55..11..11 DDEEFFIINNIITTIIOONNSS
PPRREE--CCOONNSSOOLLIIDDAATTIIOONN SSTTRREESSSS,, PP
This is the maximum stress that the soil has “felt” in the past.
CCOOMMPPRREESSSSIIOONN IINNDDEEXX,, CCCC
The compression index, CC, which indicates the compressibility of a normally-consolidated
soil.
RREECCOOMMPPRREESSSSIIOONN IINNDDEEXX,, CCRR
The recompression index, CR, which indicates the compressibility of an over consolidated
soil.
CCOOEEFFFFIICCIIEENNTT OOFF CCOONNSSOOLLIIDDAATTIIOONN,, CCVV
The coefficient of consolidation, CV, which indicates the rate of compression under a load
increment.
NNOORRMMAALLLLYY--CCOONNSSOOLLIIDDAATTEEDD SSOOIILL
A normally-consolidated soil is defined as a soil which, at the present time, is undergoing the
application of a stress that is larger than any stress it has undergone in its history.
That is, '
npresent
OOVVEERR--CCOONNSSOOLLIIDDAATTEEDD SSOOIILL
An over-consolidated soil is defined as a soil which has experienced higher stresses in the
past, '
ppresent
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 45 (BUITEMS), Quetta
CCOONNSSOOLLIIDDAATTIIOONN
When soil is loaded undrained, the pore pressures increase. Then, under site conditions, the
excess pore pressures dissipate and water leaves the soil, resulting in consolidation
settlement. This process takes time, and the rate of settlement decreases over time.
55 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT
The consolidation test is used to measure the settlement characteristics of a clay layer.
55 .. 33 SS CC OO PP EE OO FF TT EE SS TT
Consolidation is an important fundamental phenomenon which must be understood by
everyone who attempts to gain knowledge of soil behavior in engineering applications. The
main purpose of consolidation tests is to obtain soil data which is used in predicting the rate
and amount of settlement of structures founded on clay. Although some of the settlement of a
structure on clay may be caused by shear strain; most of it is normally due to volumetric
changes. This is particularly true if the clay stratum is thin compared to the width of the
loaded area or the stratum is located at a significant depth below the structure.
55 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE
ASTM: D2435-70
AASHTO: T216-66
55 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
1. Consolidometer
2. Specimen trimming device
3. Balance sensitive to 0.01 g
4. Stop watch
5. Moisture can
6. Oven
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 46 (BUITEMS), Quetta
55 .. 66 PP RR EE PP AA RR AA TT II OO NN OO FF SS AA MM PP LL EE SS AA NN DD TT EE SS TT SS PP EE CC II MM EE NN
1. Remove covering from sample.
2. Keep track of the sample orientation.
3. Place sample on wax paper disc and glass plate.
4. Rough cut the diameter with a wire saw to within 1/8" of final diameter.
5. Obtain water contents from trimmings
6. Assemble sample in trimmer with extension disc supporting soil.
7. Trim sample with cutting shoe and spatula, obtain second water content.
8. Once sample is completely fitted into specimen ring, trim top and bottom with a
wire saw. Make final cut on top surface with a sharp straight edge.
9. Obtain third and fourth water contents.
10. Use recess tool to create space at top of ring and trim excess soil from bottom with
wire saw. Make final cut with the sharp straight edge.
11. Determine the mass of the specimen and ring (Ms+r
).
12. Measure the recess from the top of ring to the soil surface (ΔHi)
Figure 5.1 One dimensional consolidation apparatus
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 47 (BUITEMS), Quetta
55 .. 77 AA DD JJ UU SS TT MM EE NN TT AA NN DD CC AA LL II BB RR AA TT II OO NN OO FF
II NN SS TT RR UU MM EE NN TT SS
55..77..11 AAPPPPAARRAATTUUSS CCAALLIIBBRRAATTIIOONN
1. Assemble the cell (stones, filter paper and top cap).
2. Align assembly in the loading frame.
3. Place a 1 lb seating load on the cell and obtain a zero reading on the displacement
transducer.
4. Apply the same loads to the apparatus as will be used in testing the specimen.
5. At each load increment, record the displacement reading at 15 sec, 30 sec, 1 min, 2
min and 5 min.
6. The change in dial reading gives the machine deflection curve.
55..77..22 AAPPPPAARRAATTUUSS PPRREEPPAARRAATTIIOONN
1. Assemble the Oedometer (stones, filter paper and top cap)
2. Measure the initial z3
(height between top of cap and specimen ring). You can place a
dummy specimen (block of known thickness) between the filter papers for added
height.
3. Disassemble the Oedometer.
4. Grease specimen ring and cutting shoe.
5. Determine the mass (Mr) of the empty specimen ring.
6. Measure the height (Hr) and diameter (D
r) of the ring.
7. Measure the thickness of one piece of filter paper (Hfp
).
8. Cut two pieces of filter paper.
9. Boil or ultrasound the stones for 10 minutes to clean and remove air
10. Cut 2 wax paper disks the diameter of the specimen.
55..77..33 AAPPPPAARRAATTUUSS AASSSSEEMMBBLLYY
1. Fill base with water.
2. Insert bottom stone into base and cover with filter paper.
3. Remove excess water with a paper towel.
4. Place specimen and ring on stone.
5. Cover rim with gasket.
6. Tighten with locking ring.
7. Cover specimen with filter paper and top stone, allow this stone to drain before
placing on soil.
8. Place top cap on stone.
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 48 (BUITEMS), Quetta
9. Measure z3
with specimen
10. Locate assembly in loading frame with dial gauge and balance arms (this is the true
weight of the assembly which is the tare load).
11. Apply one pound seating load and zero displacement transducer.
55 .. 88 TT EE SS TT PP RR OO CC EE DD UU RR EE
1. Consolidate the specimen using a load increment ratio (ΔP/P) between 0.5 and 1.0 for
loading and -0.25 and -0.50 for unloading. Note: recommended schedule S, 0.125,
0.25, 0.5, 1.0, 2, 4, 8, 4, 1, S.
2. Fill the water bath at about 1/4 the overburden stress (0.25 ksi) or within 2 hours.
3. For each increment, record the displacement transducer reading versus time.
Remember that the initial portion of the curve is very important to define the start of
consolidation (εs).
4. During each increment plot both root time and log time curves.
5. Apply increments after the end of primary consolidation has been reached.
6. Allow one cycle of secondary compression to occur under the maximum load and
before the unload-reload cycle.
7. At the end of the test unload the specimen to the seating load and allow time for
swelling.
8. Remove the water from the bath and remove the specimen from the apparatus.
9. Remove any extruded soil and oven dry.
10. Dry the surface of the specimen and determine the mass of both soil and ring.
11. Extrude the soil and obtain water content.
12. Collect washings from filter paper and inside of ring and oven dry.
55 .. 99 CC AA LL CC UU LL AA TT II OO NN SS
Initial Specimen Height = Hr – ΔH
i - H
fp
Water Content = (total mass - dry mass)/ dry mass
Note: compute the total mass during the test by subtracting (axial deformation X Area X unit
weight of water) from initial wet mass. This assumes that only water comes out of the
specimen during consolidation.
Void Ratio = (total volume - volume of solids)/ volume of solids
Volume of solids = mass of oven dried soil / specific gravity
Degree of saturation = specific gravity × water content / void ratio
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 49 (BUITEMS), Quetta
Vertical effective stress (σ'v) (when the pore pressure is zero) = (Applied load - Tare load +
top cap and stone)/ Area
Vertical strain (εv) = (measured axial deformation - Apparatus compression)/ Initial specimen
height
Note: The Apparatus compression curve is attached to this assignment
Compressibility (av) = - change in void ratio / change in vertical stress
Note: change in void ratio is usually taken at the end of primary but for this laboratory
assignment you can use end of increment values.
Coefficient of consolidation (CV). (Root time) = 0.848 (drainage height) 2
/ time for 90%
consolidation
Coefficient of consolidation (CV). (Log time) = 0.197 (drainage height) 2
/ time for 50%
consolidation
Note: Drainage height is computed at 50% consolidation for both cases.
Hydraulic conductivity (kV) = (coefficient of consolidation compressibility unit weight
of water) / (1 + average void ratio)
Rate of secondary compression (cα) = change in strain per log cycle of time after primary is
complete
Square root or time vs. Dial gauge reading
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 50 (BUITEMS), Quetta
55 .. 11 00 RR EE SS UU LL TT SS
The value of coefficient of consolidation is found to be _________
By square root method _________
55 .. 11 11 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS
In engineering practice, reasonably good predictions of a structure’s settlements can be made
from the results of carefully run laboratory tests. Predicted settlements are larger than actual
settlements more often than not. Time rate predictions are often rather poor in practice. Better
predictions, naturally, can be made for those cases which have conditions more closely in
agreement with the assumptions made in the theory derivation. This would be the case, for
example, when the soil involved experiences most of its settlement due to primary
consolidation, or when drainage conditions in the field are accurately known.
55 .. 11 22 PP RR EE CC AA UU TT II OO NN SS
1. Handling of instrument must be with care.
2. Readings should be note down carefully.
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 51 (BUITEMS), Quetta
55 .. 11 33 SS AA MM PP LL EE PP RR OO BB LL EE MM
GENERAL REPORT
CONSOLIDATION TEST
(Time vs. vertical dial reading)
Client Name ________________________
Company Name _____________________
Project Name _______________________
Project No. _________________________
Location of site _____________________
Date of sampling ____________________
Date of testing ______________________
Reporting Name ____________________
Pressure on specimen ________________
Sample No. _________B-24___________
Boring No. _________________________
Depth of sample ____2 ft______________
Description of Sample _____silty_______
Tested by __________________________
Comments. _________________________
Location ___________________________
Date ______________________________
Clock time of load application __________
Time after load
application
t
(min)
(t)1/2
(min 0.5
)
Vertical dial
reading
(in)
9:15 AM 0 0
09:15.1 0.1 0.316228
9:15:25 0.25 0.5
09:15.5 0.5 0.707107
9:16 1 1
9:17 2 1.414214
9:19 4 2
9:23 8 2.828427
9:30 15 3.872983
9:45 30 5.477226
10:15 60 7.745967
11:15 120 10.95445
1:15 PM 240 15.49193
5:15 480 21.9089
8:15 AM 1380 37.14835
CALCULATIONS
RESULT
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 52 (BUITEMS), Quetta
GENERAL REPORT
CONSOLIDATION TEST
(Void ratio-pressure and coefficient of consolidation calculation)
Client Name ________________________
Company Name _____________________
Project Name _______________________
Project No. _________________________
Location of site _____________________
Date of sampling ____________________
Date of testing ______________________
Reporting Name ____________________
Specimen diameter __________________
Moisture content: beginning of test __ (%)
Weight of dry soil specimen ___________
Sample No._________________________
Boring No. _________________________
Depth of sample _____________________
Description of Sample ________________
Tested by __________________________
Comments _________________________
Location ___________________________
Date ______________________________
Initial specimen height, Ht(i)___________
Moisture content: End of test ________(%)
Gs ___ Height of solids, Hs_________ cm
Pressure
P
(T/ft2)
Final
Dial
Reading
(in)
Change
in
specimen
height
(in)
Final
specimen
Height
Ht(f)
(in)
Height
of void
Hv
(in)
Final
void
ratio
e
Average
height during
consolidation,
Ht(av)
(in)
Fitting time
(sec)
cv from
x
103(in2/sec)
t90
t50
t90
t50
CALCULATIONS
RESULTS
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 53 (BUITEMS), Quetta
Dial Readings vs Time
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.1 1 10 100 1000 10000
Time (min)D
efo
rma
tio
n d
ial re
ad
ing
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 54 (BUITEMS), Quetta
SOIL TESTING LABORATORY
CONSOLIDATION TEST
(Void ratio-pressure)
Void Ratio
Initial void ratio, eo 1.248781
Volume of solid in specimen, Vs 27.90809
Area of specimen, A (cm2) 31.67736
Height of solid in specimen, Hs (cm) 0.881011
Pressure,
P(tons/ft2)
Initial
deformation
dial reading at
beginning of
first loading(in.)
Deformation dial
reading
representing
100% primary
consolidation, (in.)
Change in thickness of
specimen, ΔH(cm)
Change in
void ratio, De
[Δe=ΔH/ Hs]
Void Ratio,
e (e=eo-Δe)
5 6 7 (8)=((7)-(6))*2.54 (9)=(8)/(4) (10)=(1)-(9)
0 0 0 0 0 1.25
0.4 0 0.0158 0.04013 0.04555 1.204447
0.8 0 0.0284 0.07214 0.08188 1.16812
1.6 0 0.049 0.12446 0.14127 1.108729
3.2 0 0.0761 0.19329 0.2194 1.030597
6.4 0 0.1145 0.29083 0.33011 0.919886
12.8 0 0.158 0.40132 0.45553 0.794472
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 55 (BUITEMS), Quetta
(Coefficient of consolidation calculation)
Pressure,
P,
(tons/ft2)
Initial
height of
specimen
at
beginning
of test, Ho
(in)
Deformation
dial reading
at 50%
consolidation
(in)
Thickness of
specimen at
50%
consolidation,
(in)
Half
thickness of
specimen at
50%
consolidation
(in)
Time for 50%
consolidation
(min)
Coefficient of
consolidation
(in2/min)
(1) (2)
(3)
(from dial
reading vs
log of time
curves)
(4)=(2)-(3) (5)=(4)/2
(6)
(from dial
readings
versus log of
time curves)
(7)=0.196(5)2/(6)
0 0.78
0.4 0.78 0.0108 0.7692 0.3846 8.2 0.003536
0.8 0.78 0.0233 0.7567 0.37835 6.4 0.004384
1.6 0.78 0.0398 0.7402 0.3701 4 0.006712
3.2 0.78 0.0644 0.7156 0.3578 3.4 0.00738
6.4 0.78 0.0982 0.6818 0.3409 3.5 0.006508
12.8 0.78 0.1387 0.6413 0.32065 4 0.005038
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 56 (BUITEMS), Quetta
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 57 (BUITEMS), Quetta
Result
The value of coefficient of consolidation is found to be
By square root method =
By logarithm method =
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 58 (BUITEMS), Quetta
SOIL TESTING LABORATORY
CONSOLIDATION TEST
Specimen Data
At beginning of test
Type of specimen(checked one)
undisturbed
remolded
Diameter of specimen, D( in.)
Area of specimen , A in.2
Initial height of specimen, Ho ( in.)
Initial volume of specimen (in.3)
Weight of specimen ring +specimen (g)
Weight of specimen ring (g)
Initial wet weight of specimen (g)
Initial wet unit weight
Initial moisture content (%)
Can no.
Weight of wet soil + can (g)
Weight of dry soil + can (g)
Weight of can (g)
Weight of water (g)
Weight of dry soil (g)
Initial moisture content (g)
Initial dry weight of specimen (computed) (g)
Specific gravity of soil
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 59 (BUITEMS), Quetta
Volume of solid in soil specimen cm3
Volume void in soil specimen cm3
volume of water in soil specimen cm3
(Note: Unit weight of water = 1 g/cm3)
Initial degree of saturation
At the End of test
Can no.
Weight of can + wet specimen removed from
Consolidometer (g)
Weight of can + oven dried specimen (g)
Weight of can (g)
Final weight of water in specimen
Final dry weight of specimen
Final moisture content
Final degree of saturation %
Initial void ratio
Volume of solid in specimen cm3
Initial volume of specimen cm3
Initial volume of void in specimen cm3
Initial void ratio, eo
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 60 (BUITEMS), Quetta
(Time vs. vertical dial reading)
Pressure on specimen
Clock time of load application
Time after load application
t
(min)
(t)1/2
(min 0.5
)
Vertical dial
reading
(in)
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 61 (BUITEMS), Quetta
SOIL TESTING LABORATORY
CONSOLIDATION TEST
(Void ratio-pressure)
Void Ratio
Initial void ratio, eo
Volume of solid in specimen, Vs
Area of specimen, A (cm2)
Height of solid in specimen, Hs (cm)
Pressure,
P
(tons/ft2)
Initial
deformation dial
reading at
beginning of
first loading
(in)
Deformation dial
reading
representing
100% primary
consolidation,
(in)
Change in thickness
of specimen,
ΔH
(cm)
Change in void
ratio,
De [Δe=ΔH/ Hs]
Void Ratio,
e (e=eo-Δe)
(5) (6) (7) (8)=((7)-(6))2.54 (9)=(8)/(4) (10)=(1)-(9)
One Dimensional Consolidation Test
Balochistan University of of Information Technology Engineering & Management Sciences 62 (BUITEMS), Quetta
(Coefficient of consolidation calculation)
Pressure,
P,
(tons/ft2)
Initial height of
specimen at
beginning of
test, Ho
(in)
Deformation
dial reading at
50%
consolidation
(in)
Thickness of
specimen at
50%
consolidation,
(in)
Half thickness
of specimen at
50%
consolidation
(in)
Time for 50%
consolidation
(min)
Coefficient of
consolidation
(in2/min)
(1) (2)
(3)
(from dial
reading vs log of
time curves)
(4)=(2)-(3) (5)=(4)/2
(6)
(from dial
readings versus
log of time curves)
(7)=0.196(5)2/(6)
Result
The value of coefficient of consolidation is found to be
By square root method =
By logarithm method =
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 63 (BUITEMS), Quetta
6 STANDARD
PENETRATION
TEST
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 64 (BUITEMS), Quetta
66 .. 11 II NN TT RR OO DD UU CC TT II OO NN
If the test is to be carried out in gravelly soils the driving shoe is replaced by a solid 600 cone.
There is evidence that slightly higher results are obtained in the same material when the
normal driving shoe is replaced by the 600 cone.
The Standard Penetration Test was developed around 1927. It is estimated that 85% to 90%
of conventional foundation design in North and South America is made using the SPT. This
dynamic penetration test is used to assess the density index and to determine the bearing
capacity of a sand deposit. This dynamic penetration test is used to assess the density index
and to determine the bearing capacity of a sand deposit.
The test is performed using a split barrel sampler, 50 mm external diameter, 35 mm internal
diameter and about 450 mm (18in) in length, connected to the end of boring rods. The
sampler is driven into the sand at the bottom of a cased borehole by means of 65 kg hammer
falling freely through a height of 760 mm (30 in) onto the top of the boring rods.
Figure 6.1 Arrangement of SPT
Different methods of releasing the hammer are used in different countries. The borehole must
be cleaned out to the required depth, care must be taken to ensure that the material to be
tested is not distributed: jetting, as part of the boring operation is undesirable. The casing
must not be driven below the level at which the test is to begin.
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 65 (BUITEMS), Quetta
Initially the sampler is driven 150mm (6in) into the sand to seat the device and to bypass any
disturbed sand at the bottom of the borehole. The number of blows required to drive the
sampler a further 300 mm (12in) is then recorded: this number is called the standard
penetration resistance (N). The number of blows required for each 150 mm (6in) of
penetration (including the initial drive) should be recorded separately. If 50 blows are
reached before a penetration of 300mm (12in), no further blows should be applied but the
actual penetration should be recorded. At the conclusion of a test the sampler is withdrawn
and the sand extracted. Tests are normally carried out at interval of b/w 0.75 and 1.5m to a
depth below foundation level at least equal to the width (B) of the foundation
66 .. 22 OO BB JJ EE CC TT OO FF TT EE SS TT
To determine the load bearing capacity of soils by standard penetration test. The object of the
test is to determine the relative density and bearing capacity of granular sandy soils.
66 .. 33 SS CC OO PP EE OO FF TT EE SS TT
This test method describes the procedure, generally known as the Standard Penetration Test
(SPT), for driving a split-barrel sampler to obtain a representative soil sample and a measure
of the resistance of the soil to penetration of the sampler.
This standard does not purport to address all of the safety problems, if any, associated with
its use. It is the responsibility of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory limitations prior to use.
Figure 6.2 Equipment as mentioned under heading
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 66 (BUITEMS), Quetta
66 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE
ASTM: D1586
66 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
The test equipment consists of:
1. Standard split-barrel Sampler (Split-spoon)
2. A casing or Drilling.
3. A thick wall Split tube Sampler, with 2” (5.08cm) OD and 1.5” (3.5cm) ID having the
tube length of 18” to 24” long.
4. Guide rod. (30” or 76cm length)
5. Hammer having weight of 140lb (623N)
6. Rope.
7. Tripods
8. Steel chain (3m approx)
9. Lever support and rod
10. Pipe wrench and chain wrench
11. Pulley
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 67 (BUITEMS), Quetta
Figure 6.3 Solid tube sampler and driving sample
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 68 (BUITEMS), Quetta
66 .. 66 TT EE SS TT PP RR OO CC EE DD UU RR EE
1. Attach the Standard split-barrel Sampler (Split-spoon) to the bottom of the drilling
rod. The top of the drilling rod is attached by anvil used to transfer the hammer load
to the drilling rod. The anvil connects a guide rod passing through the drop hammer.
2. Erect the tripod so that each leg must form an angle of 1200 with respect to the other
and at equidistant from the center mark. Hookup pulley to the tripod with a rope
passing over it, and connect one end of the rope with drop hammer to lift it up.
3. Excavate a circular or rectangular trench upto the required foundation depth (below
which the bearing capacity of the soil is required) at the center mark..
4. Gradually pull the other end of the rope (manually or by some mechanical
arrangements) to erect the sampler. Make sure that the sampler assembly is vertically
erected at the center mark of the testing spot in excavation.
5. Now pull the rope slowly to lift the drop hammer to the full height of the guide rod
(76cm approximately) and then suddenly release the rope to provide free fall to the
hammer repeatedly to drive the Standard split-barrel Sampler (Split-spoon) 18" into
the soil.
6. After driving the sampler 18" into the soil count the number of blows, which are
required to penetrate each of three 6" increments separately. The Standard Penetration
Resistance value (N-value) is the number of blows required to penetrate the last 12",
thus the N-value represents the number of blows per foot.
7. After blow counts have been obtained, remove and open the split–spoon Sampler to
obtain a disturbed sample for subsequent examination and testing.
8. Determine the specific weight of the soil on the spot of the boring log to obtain the
effective overburden pressure.
66 .. 77 CC AA LL CC UU LL AA TT II OO NN SS
Relation between N and (peck, 1974)
Corrected N 5 10 15 20 25 30 35 40 45 50
28.5 30 32 33 35 36 37.5 39 40 43
Allowable bearing capacity using N-values
66..77..11 TTEERRZZAAGGHHII AANNDD PPEECCKK MMEETTHHOODD
Terzaghi and Peck (1948) recommended that N values should be determined between
foundation level and a depth of approximately B below the foundation. They proposed a
correlation between allowable bearing capacity and the corrected N-values in the form of a
chart. The breadth of footing and the corrected N-value are used as entry data and the
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 69 (BUITEMS), Quetta
allowable bearing capacity (qTP) is read off the left vertical axis. For Correction there is also
a formula, which is given as follow:
`
2000 log77.0
NC
The effect of the water table may be taken into account by applying the following correction
BD
D1
2
1C w
w
Where
Dw = Depth of water table below the surface.
D = Foundation depth below the surface.
B = Footing breadth.
Thus,
TPwa qCq
The Terzaghi and Peck method yields quite conservative values of qa, since it attempts to
ensure that the settlement is nowhere greater than 25mm, for wide footings and rafts the
limiting values may be raised to 50 mm. The qTP value is the function of SPT resistance value
N, and the breadth of footing. The required graph can be found in any Soil Mechanics Text
Book.
66..77..22 MMEEYYEERRHHOOFF MMEETTHHOODD
Meyerhof (1965) suggested that the qTP value could be increased by 50 % and that no
correction should be made for the water table since the effect would be incorporated in the
measured N-values. Meyerhof also proposed a set of simple design relationships as follows:
1.25mBfor 9.1
Ns
q La
:raftsfor 84.2
1.25mBfor 33.0
84.2
2
Nsq
B
BNsq
La
La
Where
SL = permitted settlement limit (mm).
N = average N-values between z = D and z = D + B.
B = breadth of footing.
66..77..33 BBUURRLLAANNDD AANNDD BBUURRBBIIDDGGEE MMEETTHHOODD
Burland and Burbidge (1985) using a large number of settlement observations concluded that
the depth of the zone of influence must be considered in which 75% of the settlement will
occur and which may be taken approximately as: Bln77.0
i eZ
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 70 (BUITEMS), Quetta
Thus the average measured N-value is therefore taken between Z = D and Z = D + Zi
The compressibility of soil is stated in terms of average N-value as a grade of compressibility
and compressibility index as follow
4.1cN
71.1I
The allowable bearing capacity of soil is thus will be given as follow
`3
2
IB
Sq
c7.0
La
` is the effective overburden pressure measured from top surface to the depth of foundation.
66 .. 88 RR EE SS UU LL TT SS
SL = ____________,
B = _____________,
Nav = ___________
No. Method Bearing Capacity Average
1 Terzaghi and Peck
2 Meyerhof
3 Burland and Burbidge
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 71 (BUITEMS), Quetta
66 .. 99 SS AA MM PP LL EE PP RR OO BB LL EE MM
SOIL TESTING LABORATORY
STANDARD PENETRATION TEST
Sample No. 15 Project No. SR 2828
Boring No. B-21 Location Newell, N.C
Depth of sample 3 ft
Description of Sample Reddish brown silty clay
Tested by John Doe Date 1/26/89
Specimen diameter cm
Depth (z) 3.5’ (1.07m)
No. of
Blows
per 6”
1st 8
2nd 16
3rd 27
N 16 + 27=43
(KN/m2) 19
z (KN/m2) 20.27
wzu 0
u` (KN/m2) 20.27
`
2000log77.0
NC
1.536
N` =CN N 66.027
Average: N 66.027
SL = 25.1 mm
B = 1.06 m
Nav = 66
No. Method Bearing Capacity Average
1 Terzaghi and Peck 1320 KN/m2
2485.8KN/m2 2 Meyerhof 882.6 KN/m
2
3 Burland and Burbidge 5254.9 KN/m2)
Standard Penetration Test
Balochistan University of of Information Technology Engineering & Management Sciences 72 (BUITEMS), Quetta
SOIL TESTING LABORATORY
STANDARD PENETRATION TEST
Sample No. Project No.
Boring No. Location
Depth of sample
Description of Sample
Tested by Date
Specimen diameter cm
Depth (z)
No. of
Blows
per 6”
1st
2nd
3rd
N
z
wzu
u`
CN =
`
2000log77.0
N` =CN N
Aver: N
Result
SL =
B =
Nav =
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 73 (BUITEMS), Quetta
7 UNCONFINED
COMPRESSION
TEST
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 74 (BUITEMS), Quetta
77 .. 11 II NN TT RR OO DD UU CC TT II OO NN
When the method of testing tube-recovered cohesive soil sample compression was first
introduced, it was widely accepted as a means of rapidly evaluating the shear strength of a
soil. From Mohr’s circle construction; it is evident that the shear strength or cohesion of a
soil sample can be approximate where qu is always used as the symbol for the unconfined
compressive strength of the soil. This computation is based on the fact that the minor
principal stresses 3 are zero (atmospheric), and the angle of internal friction of the soil is
assumed zero. With more knowledge concerning soil behavior available, it became evident
that the unconfined compression test does generally provide a very reliable value of soil
shear strength for at least three reasons:
1. The effect of lateral restraint provided by the surrounding soil mass on the sample is
lost when the sample is removed from the ground. There is, however, some opinion
that the soil moisture is provides a surface tension (or confining) effect so that the
sample is somewhat “confined”. This effect should be more pronounced if the sample
is saturated or nearly so. This effect will depend also on the relative humidity of the
testing area making a quantitative evaluation of it rather difficult.
2. The internal soil condition (the degree of saturation, the pore water pressure under
stress deformation, and the effects of altering the degree of saturation) cannot be
controlled.
3. The friction on the end of the sample from the loading platens provides a lateral
restraint on the ends, which alters the internal stresses, an unknown amount.
Table 7.1 Relative consistency as a function of unconfined compressive strength
Consistency qu (lb/ft2)
Very soft <250
Soft 250-500
Medium 5000-1000
Stiff 1000-2000
Very stiff 2000-4000
Hard >4000
77..11..11 DDEEFFIINNIITTIIOONNSS
UUNNCCOONNFFIINNEEDD CCOOMMPPRREESSSSIIVVEE SSTTRREENNGGTTHH
The compressive stress at which an unconfined cylindrical specimen of soil will fail in a
simple compression test. In this test method, unconfined compressive strength is taken as the
maximum load attained per unit area or the load per unit area at 15% axial strain, whichever
is secured first during the performance of a test.
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 75 (BUITEMS), Quetta
SSHHEEAARR SSTTRREENNGGTTHH
The shear strength of soil is the resistance to deformation by continuous shear displacement
of soil particles or on masses upon the action of shear stress.
For unconfined compressive strength test specimens, the shear strength is calculated to be ½
of the compressive stress at failure.
77 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT
This method determines the unconfined compressive strength (qu) of the soil sample.
77 .. 33 SS CC OO PP EE OO FF TT EE SS TT
This test method covers the determination of the unconfined compressive strength of
cohesive soil in the undisturbed, remolded, or compacted condition, using strain-controlled
application of axial load.
This test method provides an approximate value of the strength of cohesive soils in terms of
total stresses.
This test method is applicable only to cohesive materials which will not expel bleed water
(water expelled from the soil due to deformation or compaction) during the loading portion
of the test and which will retain intrinsic strength after removal of confining pressures, such
as clays or cemented soils. Dry and crumbly soils, fissured or varved materials, silts, peats,
and sands cannot be tested with this method to obtain valid unconfined compressive strength
values.
This test method is not a substitute for AASHTO T 234-85 which is ‘Strength Parameters of
Soils using Triaxial Compression’.
The values stated in SI units are to be regarded as the standard. The values stated in inch-
pound units are approximate.
77 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE
ASTM: D2166-66
AASHTO: 208-70
77 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
1. Unconfined compression testing machine (Triaxial Machine)
2. Specimen preparation equipment
3. Sample extruder
4. Balance
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 76 (BUITEMS), Quetta
77 .. 66 PP RR EE PP AA RR AA TT II OO NN OO FF SS AA MM PP LL EE SS AA NN DD TT EE SS TT SS PP EE CC II MM EE NN
77..66..11 PPRREEPPAARRAATTIIOONN OOFF UUNNDDIISSTTUURRBBEEDD SSAAMMPPLLEE
1. Obtain a sample and using the wire saw and miter box, trim the ends parallel to each
other.
2. Place the sample in the soil lathe and trim it to a circular cross-section.
3. Reposition the sample in the miter box and cut it to a length of approximately 7 cm
by trimming both ends.
4. Measure the average length and diameter of the sample using the veneer caliper.
Weigh the sample.
5. Use the sample trimmings to determine water content of the clay.
77..66..22 PPRREEPPAARRAATTIIOONN OOFF RREEMMOOUULLDDEEDD SSAAMMPPLLEE
1. Remold the clay thoroughly.
Figure 7.1 Unconfined Compression Testing Device
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 77 (BUITEMS), Quetta
2. Reform a cylindrical specimen using the sample former, taking care not to entrap air
in to the clay.
3. Extrude the sample from the mould and square its ends using the miter box.
4. Measure the sample as before.
77 .. 77 AA DD JJ UU SS TT MM EE NN TT AA NN DD CC AA LL II BB RR AA TT II OO NN OO FF
II NN SS TT RR UU MM EE NN TT SS
Standard Geotest unconfined compression machines are supplied with a double proving ring
or load cell and digital display which reads directly to 0.1 lbf or 1N and have a peak hold.
Proving ring models include a calibration chart in both pounds and SI units. Pounds will be
supplied unless SI units are specified. Strain is measured with a 1" travel (25mm on SI
versions) dial indicator. 2" (50mm) dial indicators or EDDIs can replace dial indicator as an
added option.
77 .. 88 TT EE SS TT PP RR OO CC EE DD UU RR EE
1. Remolded specimens are prepared in the laboratory depending on the proctors data at
the required molding water content.
2. If testing undisturbed specimens retrieved from the ground by various sampling
techniques, trim the samples into regular triaxial specimen dimensions (2.8” x 5.6”)
3. There will be a significant variation in strength of undisturbed and remolded samples.
4. Measure the diameter and length of the specimen to be tested
5. If curing the sample (treated soils), wrap the samples in a geotextile and then a zip
bag. Place the sample in a humidity room maintained at a relative humidity of 90%
6. Prior to testing, avoid any moisture loss in the sample, place on a triaxial base
(acrylic). The ends of the sample are assumed to be frictionless
7. The triaxial cell is placed above the sample and no confinement is applied
8. The rate of strain is maintained at 1.2700 mm/min as per ASTM specifications.
9. The data acquisition system collects real time data and the test is stopped when there
is a drop observed in the strain versus load plot
77 .. 99 CC AA LL CC UU LL AA TT II OO NN SS
Calculate the water contents, Axial load (P = Load Ring Reading x [Calibration of
load ring]), strain ( = ΔL/L0 x 100%), instantaneous area (Ai = A0/(1- ), where is
in decimal format), and σ1 = P/A.
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 78 (BUITEMS), Quetta
77 .. 11 00 RR EE SS UU LL TT SS
Plot a graph of σ 1 or the deviator stress as ordinate vs. ez or vertical strain in % as
abscissa on Cartesian graph paper. Define qu at failure; this is s1 (peak).
77 .. 11 11 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS
1. The test results provide an estimate of the relative consistency of the soil as can be
seen in Table 6.1.
2. Almost used in all geotechnical engineering designs (e.g. design and stability
analysis of foundations, retaining walls, slopes and embankments) to obtain a rough
estimate of the soil strength and viable construction techniques
3. To determine Undrained Shear Strength or Undrained Cohesion (Su or Cu) = qu/2
4. The unconfined compression test is usually made on undisturbed samples. It is
reasonably simple and rapid to perform. It gives a very good measure of the shearing
strength of cohesive soils. In somewhat granular soil its application is limited, but it
does provide a good supplementary test for more complex strength tests.
5. The unconfined compression test is limited in that test conditions can be varied very
little. Hence, the test may provide a good measure of the in-situ strength, but may
provide only limited strength data, as the stress conditions change due to loading or
construction.
77 .. 11 22 PP RR EE CC AA UU TT II OO NN SS
1. Scale must be precise.
2. Width of groove must be accurate.
3. Depth of groove must be accurate.
4. Handle of turning pace should be done with care.
5. Length of closure should be of ½ inch
Figure 7.2 Failure patterns typical of brittle specimen
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 79 (BUITEMS), Quetta
77 .. 11 33 SS AA MM PP LL EE PP RR OO BB LL EE MM
SOIL TESTING LABORATORY
UNCONFINED COMPRESSION TEST Sample No. 15 Project No. SR 2828
Boring No. B-21 Location Newell, N.C
Depth of sample 3 ft
Description of Sample Reddish brown silty clay
Tested by John Doe Date 1/26/89
Proving ring calibration factor 6000 (lb/in)
Specimen
deformatio
n = L
(in)
Vertical
strain
= L / L
Proving
ring dial
reading
[No. of
small
divisions]
Load =
(Col. 3)
calibration
factor
(lb)
Corrected
area =
1
AA 0
c
(in2)
Stress =
(col.4)/(col.5)
(lb/in2) or kPa
(1) (2) (3) (4) (5) (6)
0 0 0 0 4.91 0
0.025 0.004181 0.0024 14.4 4.930613 2.920529
0.05 0.008361 0.0058 34.8 4.9514 7.028316
0.075 0.012542 0.0086 51.6 4.972362 10.37736
0.1 0.016722 0.0116 69.6 4.993503 13.93811
0.125 0.020903 0.015 90 5.014825 17.94679
0.15 0.025084 0.0176 105.6 5.036329 20.96765
0.175 0.029264 0.0208 124.8 5.058019 24.67369
0.2 0.033445 0.0224 134.4 5.079896 26.45723
Result
Plot a graph of s1 or the deviator stress as ordinate vs. ez or vertical strain in % as abscissa on
Cartesian graph paper. Define qu at failure; this is s1 (peak).
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 80 (BUITEMS), Quetta
Relationship between load per unit
area and unit strain
0
5
10
15
20
25
30
0 5 10 15
Unit Strain (in/in)
Lo
ad
Per
Un
it A
rea
(lb
/in
2)
Unconfined Compression Test
Balochistan University of of Information Technology Engineering & Management Sciences 81 (BUITEMS), Quetta
SOIL TESTING LABORATORY
UNCONFINED COMPRESSION TEST
Sample No. Project No.
Boring No. Location
Depth of sample
Description of Sample
Tested by Date
Specimen
deformatio
n = L
(in)
Vertical
strain
= L / L
Proving
ring dial
reading
[No. of
small
divisions]
Load =
(Col. 3)
calibration
factor
(lb)
Corrected
area =
1
AA 0
c
(in2)
Stress =
(col.4)/(col.5)
(lb/in2) or kPa
Result
Plot a graph of s1 or the deviator stress as ordinate vs. or vertical strain in % as abcissa on
Cartesian graph paper. Define qu at failure; this is s1 (peak).
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 82 (BUITEMS), Quetta
8 TRIAXIAL TEST
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 83 (BUITEMS), Quetta
88 .. 11 II NN TT RR OO DD UU CC TT II OO NN
From an inspection of the triaxial apparatus, it is concluded that any soil pore-fluid state, from
a negative or vacuum state to a fully saturate state with an excess pore-fluid pressure, can be
obtained with this equipment. Drained or undrained conditions can be investigated. For a
drained test, as the load is applied to the soil specimen, one can allow the pore fluid to escape
by opening the appropriate valve. An undrained test can be performed by closing the soil
system to the atmosphere so that no pore fluid can escape during the test.
88..11..11 DDEEFFIINNIITTIIOONNSS
UUNNCCOONNSSOOLLIIDDAATTEEDD--UUNNDDRRAAIINNEE TTEESSTT
Which is also called the quick test (abbreviation commonly used are UU and Q test). This test
is performed with the drain valve closed for all phases of the test. Axial loading is commenced
immediately after the chamber pressure σ3 is stabilized.
CCOONNSSOOLLIIDDAATTEEDD--UUNNDDRRAAIINNEEDD TTEESSTT
Also termed consolidated-quick test or R test (abbreviated CU or R). In this test, drainage or
consolidation is allowed to take place during the application of the confining pressure σ3.
Loading does not commence until the sample ceases to drain (or consolidate). The axial load
is then applied to the specimen, with no attempt made to control the formation of excess pore
pressure. For this test, the drain valve is closed during axial loading, and excess pore pressures
can be measured.
CCOONNSSOOLLIIDDAATTEEDD--DDRRAAIINNEEDD TTEESSTT
Also called slow test (abbreviated CD or S). In this test, the drain valve is opened and is left
open for the duration of the test, with complete sample drainage prior to application of the
vertical load. The load is applied at such a slow strain rate that particle readjustments in the
specimen do not induce any excess pore pressure.
Since there is no excess pore pressure total stresses will equal effective stresses. Also the
volume change of the sample during shear can be measured.
88 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT
Determination of shear parameters of soils by triaxial test.
88 .. 33 SS CC OO PP EE OO FF TT EE SS TT
Scope of this test is to determine the shear parameters, strength-deformation characteristics
pore water pressure, etc.
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 84 (BUITEMS), Quetta
From an inspection of the triaxial apparatus, it is concluded that any soil pore-fluid state, from
a negative or vacuum state to a fully saturate state with an excess pore-fluid pressure, can be
obtained with this equipment. Drained or undrained conditions can be investigated. For a
drained test, as the load is applied to the soil specimen, one can allow the pore fluid to escape
by opening the appropriate valve. An undrained test can be performed by closing the soil
system to the atmosphere.
88 .. 44 SS TT AA NN DD AA RR DD DD EE SS II GG NN AA TT II OO NN
ASTM: D2850-70
AASHTO: 234-70
Figure 8.1 Schematic diagram of triaxial test
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 85 (BUITEMS), Quetta
88 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
1. Triaxial cell.
2. Strain controlled compression machine (Figure 7.1)
3. Specimen trimmer
4. Wire saw
5. Vacuum source
6. Oven
7. Evaporating membrane
8. Calipers
9. Rubber membrane
10. Membrane stretcher
Figure 8.2 Triaxial test device
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 86 (BUITEMS), Quetta
88 .. 66 PP RR EE PP AA RR AA TT II OO NN OO FF SS AA MM PP LL EE SS AA NN DD TT EE SS TT SS PP EE CC II MM EE NN
88..66..11 PPRREEPPAARRAATTIIOONN OOFF UUNNDDIISSTTUURRBBEEDD SSAAMMPPLLEE
1. Obtain a sample and using the wire saw and miter box, trim the ends parallel to each
other.
2. Place the sample in the soil lathe and trim it to a circular cross-section.
3. Reposition the sample in the miter box and cut it to a length of approximately 7 cm by
trimming both ends.
4. Measure the average length and diameter of the sample using the veneer caliper.
Weigh the sample.
5. Use the sample trimmings to determine water content of the clay.
88..66..22 PPRREEPPAARRAATTIIOONN OOFF RREEMMOOUULLDDEEDD SSAAMMPPLLEE
1. Remold the clay thoroughly.
2. Reform a cylindrical specimen using the sample former, taking care not to entrap air in
to the clay.
3. Extrude the sample from the mould and square its ends using the miter box.
4. Measure the sample as before.
88 .. 77 TT EE SS TT PP RR OO CC EE DD UU RR EE
88..77..11 PPLLAACCEEMMEENNTT OOFF SSPPEECCIIMMEENN IINN TTHHEE TTRRIIAAXXIIAALL TTEESSTTIINNGG MMAACCHHIINNEE
1. Boil the two-porous stones to be used with the specimen.
Figure 8.3 Triaxial test apparatus
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 87 (BUITEMS), Quetta
2. De-air the lines connecting the base of the Triaxial cell
3. Attach the bottom platen to the base of the cell
4. Place the bottom porous stone (moist) over the bottom platen.
5. Take a thin rubber membrane of appropriate size to fit the specimen tightly. Take a
membrane stretcher, which is a brass tube with an inside diameter of about ¼ in
(6mm) larger than the specimen diameter. The membrane stretcher can be connected
to a vacuum source. Fit the membrane to the inside of the membrane stretcher, and lap
the ends of the membrane over the stretcher. Then apply the vacuum. This will make
the membrane form a smooth cover inside the stretcher.
6. Slip the soil specimen to the inside of the stretcher with the membrane (step5) the
inside of the membrane may be moistened for ease of slipping the specimen in. Now
release the vacuum, and unroll the membrane-form the ends of the stretcher.
7. Place the specimen (step 6) on the bottom porous stone (which is placed on the bottom
platen of the Triaxial cell), and stretch the bottom end of the membrane around the
porous stone and bottom platen. At this time, place the top porous stone (moist) and
the top platen on the specimen, and stretch the top of the membrane over it. For
airtight seals, it is always a good idea to apply some silicone grease around the top and
bottom plates before the membrane is stretched over them.
8. Using some rubber bands, tightly fasten the membrane around the top and bottom
platens.
9. Connect the drainage line leading from the top platen to the base of the triaxial cell.
10. Place the Lucite cylinder from the top platen to the base triaxial cell on the base plate
to complete the assembly.
Note
1. In the Triaxial cell, the specimen can be saturated by connecting the drainage line
leading to the bottom of the specimen to a saturation reservoir. During this process, the
drainage line leading from the top of the specimen is kept open to the atmosphere. The
saturation of clay specimens takes a fairly long time.
2. For unconsolidated undrained test, if the specimen saturation is not required,
nonporous plates can be used instead of porous stones at the top and bottom of the
specimen.
88..77..22 UUNNCCOONNSSOOLLIIDDAATTEEDD-- UUNNDDRRAAIINNEEDD TTEESSTT
1. Place the Triaxial cell (with the specimen inside it) on the platform of the compression
machine.
2. Make proper adjustment so that the piston of the triaxial cell just rests on the top
platen of the specimen.
3. Fill the chamber of the triaxial cell with water. Applying a hydrostatic pressure, 3, to
the specimen through the chamber fluid. (Note: All drainage to and from the specimen
should be closed now so that drainage from the specimen does not occur).
4. Check for proper contact between the piston and the top platen on the specimen. Zero
the dial gauge of the proving ring and the gauge used for measurement of the vertical
compression of the specimen. Set the compression machine for a strain rate of about
0.5% per minute, and turn the switch on.
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 88 (BUITEMS), Quetta
5. Take proving ring dial readings for vertical compression intervals of 0.01inch
(0.254mm) initially. This interval can be increased to 0.02 inch (0.508mm) or more
later when the rate of increase of loads on the specimen decreases. The proving ring
readings will increase to a peak value and then may decrease or remain approximately
constant. Take about four to five readings after the peak point.
6. After completion of the test, reverse the compression machine and lower the triaxial
cell, and then shut off the machine. Release the chamber pressure, and drain the water
in the triaxial cell. Then remove the specimen and determine its moisture content.
88 .. 88 CC AA LL CC UU LL AA TT II OO NN SS
1. Compute the unit strain from the deformation readings as
2. Δax = ΔL/L0 and fill in the appropriate column of the data sheet. Also compute the
adjusted instantaneous area A = Ac/ (1-Δax) and place this in the appropriate column
of the data sheet. The c subscript above refers to the fact that these should be the
dimensions not at the start of the test, but after consolidation of the specimen.
3. Compute the axial load using the load readings. If a load (proving) ring is used, the
load P is P = DR x load-ring constant where DR is the load-dial reading in units of
deflection. Put these data in the appropriate column of the data sheet.
4. Compute the principal stress difference
5. (σ1 - σ3) = P/A and fill in the appropriate column of the data sheet.
6. Knowing that
7. σ1 = σ3 + (σ1 - σ3)
8. Compute the principal stress ratio: σ1/σ3
88 .. 99 RR EE SS UU LL TT SS
1. Draw a graph of the axial strain (%) vs. deviatory stress. From this graph, obtain the
value of at failure ( = f)
2. The minor principal stress on the specimen at failure is 3 (i.e. the chamber confining
pressure). Calculate the major principal stress at failure as
31
3. Draw a Mohr’s circle with 1 and 3 as the major and minor principal stresses. The
radius of the Mohr’s circle is equal to Su.
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 89 (BUITEMS), Quetta
88 .. 11 00 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS
Triaxial test is a soils laboratory test to determine shear strength parameters. The shear
strength of soil is needed to design foundation, slopes, tunnels, dams, and other geotechnical
systems. It is a most widely used technique of determining the shear strength of soils.
Chart 8.2 Showing results of triaxial test
Chart 8.1 Showing stress vs strain curve
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10 12 14
Str
ess
chan
ge
lb/i
n2
Axial strain %
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 90 (BUITEMS), Quetta
The sample, which is cylindrical, is tested inside a Perspex cylinder filled with water under
pressure. The sample under test is enclosed in a thin rubber membrane to seal it from the
surrounding water. The pressure in the cell is raised to the desired value, and the sample is
then brought to failure by applying an additional vertical stress.
One of the major advantages of the triaxial apparatus is the control provided over drainage
from the sample. When no drainage is required (i.e. in undrained tests), solid end caps are
used. When drainage is required, the end caps are provided with porous plates and drainage
channels. It is also possible to monitor pore-water pressures during a test.
88 .. 11 11 PP RR EE CC AA UU TT II OO NN SS
1. Limit the magnitude of the excess pore pressure by testing at a very slow strain rate, as
it is impossible to have a state of no excess pore pressure
2. A drain test can take up to a week. For this duration, membrane leaks, soil set up and
equipment corrosion can be significant.
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 91 (BUITEMS), Quetta
88 .. 11 22 SS AA MM PP LL EE PP RR OO BB LL EE MM
SOIL TESTING LABORATORY
UNCONSOLIDATED UNDRAINED TRIAXIAL TEST
(Preliminary data)
Sample No. 15
Project No. SR 2828
Boring No. B-21
Location Newell, N.C
Depth of sample 3 ft
Description of Sample Reddish brown silty clay
Tested by John Doe
Date 1/26/89
Moist unit weight of specimen (beginning of test) 122.7 lb/ft3
Moisture content (end of test) 16.9 (%)
Dry unit weight of specimen 105.0 lb/ft3
Initial average length of specimen, Lo 5.82 cm
Initial average diameter of specimen, Do 2.50 cm
Initial area, Ao 4.91 cm2
Gs 2.78
Final degree of saturation 71.9 %
Cell confining pressure, σ3 10.0 psi
Proving ring calibration factor 6000 lb/in
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 92 (BUITEMS), Quetta
SOIL TESTING LABORATORY
UNCONSOLIDATED-UNDRAINED TRIAXIAL TEST
(Axial stress – strain calculation)
Specimen
deformation
= δL
(in)
Vertical
strain,
є = δL
L
Proving
ring dial
reading
Piston Load,
col.3 x c.f
(calibration
factor)
(lb)
Corrected area
=
Ac = Ao /1 – є
(in2)
Deviatory
Stress
Δσ = P/Ac
(lb/in2)
(1) (2) (3) (4) (5) (6)
0 0 0 0 4.91 0
0.005 0.0009 0.0012 7.2 4.91 1.5
0.01 0.0017 0.0025 15 4.92 3
0.015 0.0026 0.0037 22.2 4.92 4.5
0.02 0.0034 0.0053 31.8 4.93 6.5
0.025 0.0043 0.0066 39.6 4.93 8
0.05 0.0086 0.0140 84 4.95 17
0.075 0.0129 0.0201 120.6 4.97 24.3
0.100 0.0172 0.0256 153.6 5.00 30.7
0.125 0.0215 0.0294 176.4 5.02 35.1
0.150 0.0258 0.0321 192.6 5.04 38.2
0.175 0.0301 0.0337 202.2 5.06 40
0.200 0.0344 0.0331 198.6 5.08 39
.225 0.0387 0.0305 183 5.11 35.8
Result
1. Draw a graph of the axial strain (%) vs. deviatory stress. From this graph, obtain the
value of at failure ( = f)
2. The minor principal stress on the specimen at failure is 3 (i.e. the chamber confining
pressure). Calculate the major principal stress at failure as
31
3. Draw a Mohr’s circle with 1 and 3 as the major and minor principal stresses. The radius
of the Mohr’s circle is equal to Su.
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 93 (BUITEMS), Quetta
Axial Strain vs Stress
0
5
10
15
20
25
30
35
40
45
0 0.01 0.02 0.03 0.04 0.05
Axial Strain (in/in)
Str
ess (
lb/i
n2)
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 94 (BUITEMS), Quetta
SOIL TESTING LABORATORY
UNCONSOLIDATED UNDRAINED TRIAXIAL TEST
(Preliminary data)
Sample No.
Project No.
Boring No.
Location
Depth of sample
Description of Sample
Tested by
Date
Moist unit weight of specimen (beginning of test)
Moisture content (end of test)
Dry unit weight of specimen
Initial average length of specimen, Lo cm
Initial average diameter of specimen, Do cm
Initial area, Ao cm2
Gs
Final degree of saturation %
Cell confining pressure, σ3
Proving ring calibration factor
Triaxial Test
Balochistan University of of Information Technology Engineering & Management Sciences 95 (BUITEMS), Quetta
SOIL TESTING LABORATORY
UNCONSOLIDATED-UNDRAINED TRIAXIAL TEST
(Axial stress – strain calculation)
Cell confining pressure,σ3=
Specimen
deformation
= δL
(in)
(1)
Vertical
strain,
є = δL
L
(2)
Proving ring
dial reading
(3)
Piston Load,
col.3 x c.f
(calibration
factor)
(lb)
(4)
Corrected
area =
Ac = Ao /1 – є
(in2)
(5)
Deviatory
Stress
Δσ = P/A
(lb/in2)
(6)
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 96 (BUITEMS), Quetta
9 PLATE LOAD TEST
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 97 (BUITEMS), Quetta
99 .. 11 II NN TT RR OO DD UU CC TT II OO NN
1. The test results reflect only the character of the soil located within a depth less than twice
the width of the bearing plate (corresponding to an isobar of one-tenth the loading
intensity at the test plate). Since the foundations are generally large, the settlement and
resistance against shear will depend on the properties of a much thicker stratum.
2. It is essentially a short duration test, and hence the test does not give the ultimate
settlement, particularly in the case of cohesive soils.
3. Another limitation is the effect of the size of foundation. For clay soils the ultimate
pressure for a large foundation is the same as that for the test plate. But in dense sandy
soils, the bearing capacity increases, with the size the foundation, and the test on smaller
size bearing plates tend to given conservative values.
EEFFFFEECCTT OOFF TTHHEE SSIIZZEE OOFF PPLLAATTEE OONN BBEEAARRIINNGG CCAAPPAACCIITTYY
As stated in limitation 3 above, the bearing capacity of sands and gravels increase with the
size of the footing. The relationship can be expressed as under
p
f
fB
BNMq
In the above relation, M term includes the NC and Nq terms while N include N portion of
the bearing capacity equation. The above equation can also be solved graphically by using
more than one size plates
EEFFFFEECCTT OOFF SSIIZZEE OOFF PPLLAATTEE OONN SSEETTTTLLEEMMEENNTT
The settlement of a footing varies with its size. Terzaghi and peck have suggested the
following relationship b/w the settlement of plate (sp) and settlement of actual footing (sf) for
granular soils. 2
fp)3.0Bp(B
)3.0B(BpsS
If s is the permissible settlement of the foundation, the maximum settlement of the largest
forting should be restricted to 4/3s. The corresponding settlement of the test plate (Sp) on
sand, soil is given by 2
p)3.0Bp(B
)3.0B(Bps.
3
4S
DDEETTEERRMMIINNAATTIIOONN OOFF BBEEAARRIINNGG CCAAPPAACCIITTYY
By extrapolating the plate load test data, one can use the following equation for all practical
purposes to determine the bearing capacity of soil.
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 98 (BUITEMS), Quetta
p
fpf
B
Bqq
Where
qf = bearing capacity of the actual footing
Bf = width of actual footing
qp = bearing capacity, obtained from the plate load test
Bp = width of plate
However, for clays, the bearing capacity is almost independent of the footing
size or the plate size.
qf = qb
For a c- soil, housel (1992) suggested the following expression:
Q = A q + P. S
Where
Q = total load on bearing area
A = contact area of footing or plate
P = perimeter of footing
q = bearing pressure beneath area A
S = perimeter shear
DDEETTEERRMMIINNAATTIIOONN OOFF SSEETTTTLLEEMMEENNTT
Settlement of prototype foundation can be estimated from the results of plate load test using
following equations, after Terzaghi (1948).
p
fpf
B
BSS
For clays and if the sand is like an elastic material, then the settlement can be calculated from
p
2
papp IE
u1BS
Where
Sp = plate settlement
ap = applied stress
Bp = width or diameter of the of the plate
u = poisons ratio
E = elastic modulus
Ip = influence factor (0.82 for rigid plate)
The settlement of the real footing of width B is related to the plate settlement
by
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 99 (BUITEMS), Quetta
or 2
pf
2
ppf
3.0B
B2SS
BB
B2SS
for sands
Where
Sf =
settlement of a prototype foundation
Sp = settlement of square plate of 0.3 m by 0.3 m
Bf = width of prototype foundation
Bp = width of the plate
Bond (1961) has proposed the following equation for settlements 1n
f
p
Bp
B
S
S
Where
n = coefficient depending on the types of soil
The value of index n can be determined by carrying out two or more plate
load tests on different size plates. In absence of test data the following values
of n can be adopted:
Clay: 0.03 to 0.05
Sandy clay: 0.0.8 to 0.10
Dense sand: 0.4 to 0.5
Medium to dense sand: 0.25 to 0.35
Loose sand: 0.20 to 0.25
99..11..11 DDEEFFIINNIITTIIOONNSS
DDEEFFLLEECCTTIIOONN
The amount of downward vertical movement of a surface due to the application of a load to
the surface.
RREESSIIDDUUAALL DDEEFFLLEECCTTIIOONN
The difference between original and final elevations of a surface resulting from the
application and removal of one or more loads to and from the surface.
RREEBBOOUUNNDD DDEEFFLLEECCTTIIOONN
The amount of vertical rebound of a surface that occurs when a load is removed from the
surface.
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 100 (BUITEMS), Quetta
BBEEAARRIINNGG CCAAPPAACCIITTYY
The pressure that a soil sample can sustain without failing is called the bearing capacity of
soil.
SSOOIILL SSEETTTTLLEEMMEENNTT
The process of compression (reduction in the volume of voids) of soil due to the expulsion of
air, water or both from the voids as a result of increased loading (such as geostatic weight or
weight of structure above) is called soil settlement.
99 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT
This experiment is used to determine the ultimate and or safe bearing capacity of the full-
scale foundation.
99 .. 33 SS CC OO PP EE OO FF TT EE SS TT
This method covers the making of non repetitive static plate load test on subgrade soils and
flexible pavement components, in either the compacted condition or the natural state, and is
intended to provide data for use in the evaluation and design of rigid and flexible type
airport and highway pavements.
99 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE
ASTM: D1194
AASHTO T 222-81
99 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
99..55..11 FFIIEELLDD TTEESSTT AAPPPPAARRAATTUUSS
The required field test apparatus is as follows
1. Load reaction equipment. Load reaction equipment consisting of a truck, trailer,
anchored frame, or similar device having a dead load of at least 25,000 lb.
2. Bearing plates. Bearing plates consisting of a 30-in., 24-in., and 18-in.-diameter steel
plate, each plate 1 in. thick. Aluminum alloy No. 24ST plates 1.5 in. thick may be
used in lieu of steel plates.
3. Jack. Hydraulic jack capable of applying loads of at least 25,000 lb.
4. Ball joint. A ball joint to be inserted between the jack and load reaction equipment or
between the jack and bearing plates to prevent eccentricity of loading.
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 101 (BUITEMS), Quetta
5. Load-measuring device. A load-measuring device consisting of either a hydraulic
gage on the jack, a steel proving ring, or load cell. All are satisfactory for measuring
applied load, but must be accurately calibrated.
6. Micrometers. Three dial micrometers, reading to 1/10,000 in., dial stems, and support.
7. Sand/plaster of Paris. Clean sand or plaster of Paris.
8. Cribbing. Cribbing of short pieces of hardwood or steel H- or I-beams.
9. Stopwatch.
10. Containers. Containers for undisturbed soil samples.
11. Consolidometer apparatus.
12. Cutting equipment. Necessary equipment for cutting an undisturbed specimen of the
soil into a consolidometer test ring.
13. Scales
14. Oven
15. Miscellaneous tools for making moisture-content determinations.
Figure 9.1 Plate load test apparatus
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 102 (BUITEMS), Quetta
99 .. 66 TT EE SS TT PP RR OO CC EE DD UU RR EE
The test pit width is made five times the width of the plate Bp. At the center of the pit, a
small square hole is dug whose size is equal to the size of the plate and the bottom level of
which corresponding to the level of the actual foundation (figure) the depth Dp of the hole
should be such that the loading to the plate may be applied with the help of a hydraulic jack.
The reaching of the hydraulic jack may be borne by either of the following two methods
a) Gravity loading plate form method
b) Reaction truss method
In the case of gravity loading method, plate form is constructed over a vertical column
resting on the rest plate, and the loading is done with the help of sand bags, stone or concrete
blocks. The general arrangement of the test set-up for this method is shown in the figure.
When load is applied to the plate, it sinks or settles. The settlement of the plate is measured
with the help of sensitive dial gauge. For square plate, two dial gauges are used. The dial
Figure 9.2 Schematic diagram of Plate load test
Bp
5Bp
Dp
D
Bearing Plate Foundation level
Hydraulic jack
Plate form Main girder
Sand bags
Datum bar Dial gauges
Test plate
Masonry support
Loading post
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 103 (BUITEMS), Quetta
gauges are mounted on independently supported datum bar. As the plate settles, the ram of
the dial gauge moves down and settlement is recorded. The load is indicated on the load-
gauge of the hydraulic gauge of the hydraulic jack.
The load is applied with the help of a hydraulic jack (preferably with the remote control
pumping unit), in convenient increments, say of about one-fifth of the expected safe bearing
capacity or one-tenth of the ultimate bearing capacity. Dial gauges fixed at diametrically
opposite ends, with sensitivity of 0.02mm, observe settlement of the plate.
Settlement should be observed for each increment of load after an interval of 1,4,10, 20, 40
and 60 minutes and thereafter at hourly interval until the rate of settlement becomes less than
about 0.02mm per hour. After this, the next load increment is applied. The maximum load
that is to be applied corresponds to 3 time’s proposed allowable bearing pressure.
The water table has a marked influence on the bearing capacity of sand or gravelly soil. If the
water table is already above the level of the footing, it should be lowered by pumping and the
bearing plate seated after the water table has been lowered just below the footing level. Even
Figure 9.3 Schematic diagram of Plate load test
Bp
5Bp
Dp
D
Bearing Plate Foundation level
Hydraulic jack
Plate form Main girder
Sand bags
Datum bar Dial gauges
Test plate
Masonry support
Loading post
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 104 (BUITEMS), Quetta
if the water table is locate above 1 m below the base level of the footing, the load test should
be made at the level of the water table itself.
When a load settlement curve (Fig 9.2) does not indicate any marked breaking point, failure
may alternatively be assumed corresponding to settlement equal to one fifth of the width of
the test plate. In order to determine the safe bearing capacity it would be normally sufficient
to use a factor of safety of 2 or 2.5 on ultimate bearing capacity.
Chart 9.1 Load vs. Settlement
99 .. 77 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS
1. The Plate Bearing (or Loading) Test, is normally used to measure the short term
settlement of road sub-grade or building footings under their proposed design load.
The value of settlement against load is then used to check that the soil meets design
load settlement criteria. The test therefore is of use to both contractors and to
specifying authorities.
2. In addition to values of settlement, other soil parameters can be measured, or
calculated from the plate bearing test. These include Modulus of Sub-Grade Reaction,
permanent deformation characteristics of the soil and in some instances shear strength
of the soil.
3. This method of testing is used for determining the modulus of reaction of soils by
means of the plate bearing test and for determining the corrections to be applied to the
0
4
8
12
16
20
24
28
32
0 1 2 3 4 5 6 7 8 9 10
Set
tlem
ent
(mm
)
Load kg/cm square
Plate load data
Plate Load Test
Balochistan University of of Information Technology Engineering & Management Sciences 105 (BUITEMS), Quetta
field test values by means of laboratory tests. The modulus of soil reaction is required
in rigid pavement design and evaluation.
4. This test method is used to estimate the bearing capacity of a soil under field loading
conditions for a specific loading plate and depth of embedment but also for load tests
of soil and flexible pavement components for use in evaluation and design of airport
and highway pavements.
99 .. 88 PP RR EE CC AA UU TT II OO NN SS
1. Sample should make with care.
2. Apparatus should be handled carefully.
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 106 (BUITEMS), Quetta
10 CALIFORNIA
BEARING RATIO
TEST
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 107 (BUITEMS), Quetta
11 00 .. 11 II NN TT RR OO DD UU CC TT II OO NN
The CBR test was developed by California Division of Highway in 1929 as mean of classify
the suitability of a soil for use as a sub grade or base course material in highway construction.
The laboratory test measures the shearing resistance of a soil under controlled moisture and
density conditions.
1100..11..11 DDEEFFIINNIITTIIOONNSS
CCAALLIIFFOORRNNIIAA BBEEAARRIINNGG RRAATTIIOO
The CBR for a soil is the ratio (expressed as %) obtained by dividing the penetration stress
required to cause a 3-in2
area (hence, a 1.95-in. diameter) piston to penetrate 0.10 in. into the
soil by a standard penetration stress of 1,000 psi.
It may be expressed in the equation form as
1001000
).10.0(..).(.
psi
inchespenetratetorequiredpsistressnpenetratioCBR
Note: The 1,000 psi in the denominator is the standard penetration stress for 0.10 in.
penetration.
SSUUBB GGRRAADDEE
The natural soil upon which the pavement is laid. The sub grade is seldom strong enough to
carry a wheel load directly.
11 00 .. 22 OO BB JJ EE CC TT II VV EE SS OO FF TT EE SS TT
This method describes the sampling of the sub grade for California Bearing Ratio
(CBR)The resulting information is used for pavement design thickness.
11 00 .. 33 SS CC OO PP EE OO FF TT EE SS TT
This test method is used to determine layer thicknesses and in-place California Bearing Ratio
(CBR) and to obtain samples of the pavement layer, base, sub-base, and sub-grade for
laboratory testing. The test method is applicable to both asphalt concrete (AC) and Portland-
cement concrete (PCC) pavements.
The strength of the sub grade is the main factor in determining the thickness of the pavement
although its susceptibility to frost must also be considered. The value of the stiffness of the
sub grade is required if the stresses and strains in the pavement and the sub grade are to be
calculated.
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 108 (BUITEMS), Quetta
11 00 .. 44 SS TT AA NN DD AA RR DD RR EE FF EE RR EE NN CC EE
ASTM D1883-73
11 00 .. 55 MM AA TT EE RR II AA LL SS && EE QQ UU II PP MM EE NN TT
1. CBR test apparatus: Compaction mold (6-in. diameter and 7-in. height),collar, spacer
disk ( 5.937 diameter and 2.416-in. height),adjustable stem and perforated plate,
weights, penetration piston(3 in² in area)
2. Loading (compression) machine: with load capacity of at least 10,000 lb and
penetration rate of 0.05 in./min
3. Expansion measuring apparatus
4. Two dial gages (with accuracy to 0.001 in.)
5. Standard compaction hammer
6. Mixing bowl
7. Scales
8. Soaking tank
9. Oven
Figure 10.1 CBR test apparatus
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 109 (BUITEMS), Quetta
11 00 .. 66 TT EE SS TT PP RR OO CC EE DD UU RR EE
1. Place the mould with base plate containing the sample, with the top face of the
sample exposed, centrally on the lower platen of the testing machine.
2. Place the appropriate annular surcharge discs on top of the sample.
3. Fir into place the cylindrical plunger and force-measuring devise assembly with the
face of the plunger resting on the surface of the sample.
4. Apply a seating force to the plunger, depending on the expected CBR value, as
follows.
5. for CBR value up to 5%, apply 10 N
6. for CBR value from 5% to 30%, apply 50 N
7. for CBR value above 30%, apply 250 N
8. Secure the penetration dial gauge in position. Record its initial zero reading, or reset it
to read zero.
9. Start the test so that the plunger penetrates the sample at a uniform rate of
10.2mm/min, and at the same instant start the timer.
10. Record readings of the force gauge at intervals of penetration of 0.25mm, to a total
penetration not exceeding 7.5mm
11. After completing the penetration test or tests, determine the moisture content of the
test sample
12. Test results are plotted in the form of a load-penetration diagram by drawing a curve
through the experimental points. Usually the curve will be convex upwards but
sometimes the initial part of the curve is concave upwards and, over this section, a
correction becomes necessary. The correction consists of drawing a tangent to the
curve at its steepest slope and producing it back to cut the penetration axis. This point
is regarded as the origin of the penetration scale for the corrected curve.
13. Penetrations of 2.5mm and 5mm are used for calculating the CBR value. From the
test curve, with corrected penetration scale if appropriate, read off the forces
corresponding to 2.5mm and 5mm penetration. Express these as a percentage of the
standard forces at these penetrations. Take the higher percentage as the CBR value.
11 00 .. 77 EE NN GG II NN EE EE RR II NN GG UU SS EE SS OO FF TT EE SS TT RR EE SS UU LL TT SS
This test method is used to evaluate the potential strength of sub grade, sub base, and base
coarse material including recycled materials for use in road and airfield pavements. The CBR
value obtained in this test forms an integral part of several flexible pavement design methods.
For applications where the effect of compaction water content on CBR is unknown or where
it is desired to account for its effect, the CBR is determined for a range of water content,
usually the range of water content permitted for field compaction by using agency’s field
compaction specification.
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 110 (BUITEMS), Quetta
11 00 .. 88 PP RR EE CC AA UU TT II OO NN SS
1. Scale must be precise.
2. Width of groove must be accurate.
3. Depth of groove must be accurate.
4. Handle of turning pace should be done with care.
11 00 .. 99 CC AA LL CC UU LL AA TT II OO NN SS
CBR value for 2.5mm (0.1in) penetration
( ) ( )
( ) ( )
CBR value for 5.0mm (0.2in) penetration
( ) ( )
( ) ( )
11 00 .. 11 00 CC OO RR RR EE CC TT II OO NN SS TT OO CC UU RR VV EE
The correction to the curve and reading given on the next page should be done.
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 111 (BUITEMS), Quetta
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 112 (BUITEMS), Quetta
11 00 .. 11 11 SS AA MM PP LL EE PP RR OO BB LL EE MM
SOIL TESTING LABORATORY
CALIFORNIA BEARING RATIO TEST
Moisture Content Determination
Before
compaction
after
compaction
Top 1 in layer
after soaking
Average moisture
content after
soaking
can no. 1-A 1-B 1-C 1-D
weight of can, W1 (g) 45.23 47.28 43.44 46.59
weight of can + wet soil, W2 (g) 315.94 326.01 304.71 356.37
weight of can + dry soil, W3 (g) 273.69 283.37 261.53 305.82
mc (%)=(W2-W3)/(W3-W1)×100 18.49 18.06 19.79 19.50
Average moisture content before soaking (%) = 18.27
Average moisture content after soaking (%) = 19.64
Density Determination
Before soaking After soaking
weight of mold + compacted soil specimen (g) 9020.9 9036.81
Weight of mold (g) 4167.5 4167.5
Weight of compacted soil specimen (g) 4853.4 4869.31
Diameter of mold (in.) 6 6
Area of soil specimen (in2) 28.278 28.278
height of soil specimen (in.) 5 5
Volume of soil specimen (in.3) 141.39 141.39
Wet density (lb/ft3) 130.76 131.19
Moisture content (%) 18.27 19.64
Dry density (lb/ft3) 110.56 109.64
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 113 (BUITEMS), Quetta
Swell Data
Initial swell
measurement
Final swell
measurement
Surcharge weight (lb) 10 10
Time 10:16 AM 10:16 AM
Date 5/26/2006 5/30/2006
Elapsed time (hr) 0 96
Dial reading(in.) 0 0.0135
Initial height of soil specimen (in.) 5 5
Swell (% of initial height) 0 0.27
Bearing Ratio Data
Check one soaked unsoaked
Weight of surcharge (lb) 10
Proving ring calibration (lb/in) 74000
Penetration
(in)
Proving ring dial
reading (in.) Piston load (lb)
Area of piston
(in.2)
penetration stress
(psi)
1 2 3=2×proving ring
calibration 4 5=3/4
0 0 0 3 0
0.025 0.0004 29.6 3 9.86
0.05 0.0008 59.2 3 19.73
0.075 0.0013 96.2 3 32.06
0.1 0.0016 118.4 3 39.46
0.125 0.0019 140.6 3 46.86
0.15 0.002 148 3 49.33
0.175 0.0022 162.8 3 54.26
0.2 0.0023 170.2 3 56.73
0.3 0.0026 192.4 3 64.13
0.4 0.003 222 3 74
0.5 0.0032 236.8 3 78.93
Result
CBR at 0.10-in. penetration (%) = [corrected penetration stress for 0.10 in penetration (from curve of
penetration stress versus penetration)]/1000×100 = 3.95
CBR at 0.20-in. penetration (%) = [corrected penetration stress for 0.20 in penetration (from curve of
penetration stress versus penetration)]/1500×100= 3.78
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 114 (BUITEMS), Quetta
Curve of Penetration Stress vs Penetration
0
10
20
30
40
50
60
70
80
90
0 0.1 0.2 0.3 0.4 0.5 0.6
Penetration (in.)
Pe
ne
tra
tio
n s
tre
ss
(p
si)
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 115 (BUITEMS), Quetta
SOIL TESTING LABORATORY
CALIFORNIA BEARING RATIO TEST
Moisture Content Determination
Before
compaction
after
compaction
Top 1 in layer
after soaking
Average moisture
content after soaking
can no.
weight of can, W1 (g)
weight of can + wet soil, W2 (g)
weight of can + dry soil, W3 (g)
mc (%)=(W2-W3)/(W3-W1)×100
Average moisture content before soaking (%) =
Average moisture content after soaking (%) =
Density Determination
Before soaking After soaking
weight of mold + compacted soil specimen (g)
Weight of mold (g)
Weight of compacted soil specimen (g)
Diameter of mold (in.)
Area of soil specimen (in2)
height of soil specimen (in.)
Volume of soil specimen (in.3)
Wet density (lb/ft3)
Moisture content (%)
Dry density (lb/ft3)
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 116 (BUITEMS), Quetta
Swell Data
Initial swell
measurement Final swell measurement
Surcharge weight (lb)
Time
Date
Elapsed time (hr)
Dial reading(in.)
Initial height of soil specimen (in.)
Swell (% of initial height)
Bearing Ratio Data
Check one soaked unsoaked
Weight of surcharge (lb)
Proving ring calibration (lb/in)
Penetration (in) Proving ring dial
reading (in.) Piston load (lb)
Area of piston
(in.2)
penetration
stress (psi)
1 2 3=2×proving ring
calibration 4 5=3/4
California Bearing Ratio Test
Balochistan University of of Information Technology Engineering & Management Sciences 117 (BUITEMS), Quetta
Result CBR at 0.10-in. penetration (%) = [corrected penetration stress for 0.10 in penetration (from curve of
penetration stress versus penetration)]/1000×100 =
CBR at 0.20-in. penetration (%) = [corrected penetration stress for 0.20 in penetration (from curve of
penetration stress versus penetration)]/1500×100=
Bibliography
Balochistan University of of Information Technology Engineering & Management Sciences 118 (BUITEMS), Quetta
BIBLIOGRAPHY
Bibliography
Balochistan University of of Information Technology Engineering & Management Sciences 119 (BUITEMS), Quetta
BB II BB LL II OO GG RR AA PP HH YY
Braja M. Das, Soil Mechanics Lab Manual,
Arpad Kezdi, Hand Book of Soil Mechanics and Soil Testing,
K. H. Head, Manual of Soil Laboratory Testing,
Joseph E. Bowles, Engineering Properties of Soil and Their Measurements, fourth edition,
BS 1377: Part 2 (1990), British Standard Methods of Test for Soil for Engineering Purposes.
Cheng Liu, Jack B. Evett, Soil Properties (Testing, Measurement and Evaluation), second
edition,
W. L. Schroeder, Soil in Construction (fifth edition),
ASTM 1988 ‘Annual book of ASTM Standards’
Book of Standards Volume: 04, Publisher: Taylor & Francis, Volume 22, Number 7 / 2004
Ashworth Manual, Embankment and Bas’,
Prof. Krishna Reddy, UIC, Engineering Properties of Soils Based on Laboratory Testing
Soil mechanics work book
Dr. J. T. Germaine, Civil engineering material laboratory
Bardet, Jean-Pierre. (1997), Experimental Soil Mechanics. Prentice-Hall,
Means, R.E. and Parcher, J.V. (1963), Physical Properties of Soils
Ajay K. Duggal and Vijay P. Puri, Laboratory Manual in Highway Engineering,
H. S. Moondra, Rajiv Gupta, Lab Manual for Civil Engineering,
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http://www.mastrad.com/speed.htm
http://www.geneq.com/catalog/en/large_speedy.html
http://www.mbt.co.id/equipment/so-430.html
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Balochistan University of of Information Technology Engineering & Management Sciences 120 (BUITEMS), Quetta
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