Post on 01-Nov-2015
description
Significance of site investigation Significance of site investigation
and geotechnical characterization and geotechnical characterization
using Field methodsusing Field methods
Dr D Neelima Satyam
Assistant Professor
IIIT Hyderabad
Virtually every structure is
supported on soils; whose which
are not, either fly, float or fall over
Natural aggregates of mineral grains, loose or moderately
cohesive inorganic or organic in nature that have the
capacity of being separated by means of simple mechanical
processes.
Structures are built with soil
Dams , embankment
Structures are built in soil
Structural foundations footings, piles, rafts, tunnels
SOIL :SOIL :
Geotechnical engineeringGeotechnical engineering
A unique combination of science, experience, judgment and a
passion for understanding the uniqueness and variability of
ground conditions resulting from the forces of nature.
It is the art of determining the properties of unseen and
variable materials to provide a facility that perform as
expected at acceptable level of risk and at an optional cost.
Foundation EngineeringFoundation Engineering
In a broad sense, foundation engineering is a art of selecting,
designing and constructing the elements that transfer the weight of
structure to the underlying soil or rock.
The role of engineer is to select the type of foundation, its design
and supervision of construction.
Before the engineer can design a foundation intelligently, he must
have a reasonably accurate conception of the physical properties
and the arrangement of the underlying materials. This requires
detailed soil explorations.
General ObservationGeneral Observation
1. Soil does not posses a unique or linear stress-strain relationship.
2. Soil behavior depends up on the pressure, time and environment.
3. Soil at every location is essentially different
4. Nearly in all the cases, the mass of soil involved is underground and cannot be seen entirely, but must be evaluated on the basis of small size samples, obtained from isolated locations.
5. Most soils are very sensitive to disturbance from sampling and thus the behavior measured by a lab test may be unlike that of in situ soil.
The lowest part of a structure is generally referred to as foundation.
Definition of foundationDefinition of foundation
To transfer load of the superstructure to the soil on which it is
resting.
Function of foundationFunction of foundation
A properly designed foundation is one that transfers the structural
load throughout the soil without overstressing of soil which can
result in either excessive settlement or shear failure,
both of which can damage the structure.
RequirementsRequirements (Functional)(Functional)
Foundation Engineering
Loads can be static or dynamic
Static: Building, structure, dam, retaining wall,
embankment, etc.
Dynamic: Earthquake, vibrating equipment, or
sensitive equipment
Subsurface Exploration
Purpose of subsoil exploration
Steps in Soil/Rock exploration
Collection of Preliminary information: type of
structure, general use, topography, GWT
map, soil map
Reconnaissance survey
Site investigation: Planning, test boreholes,
collecting soil samples
Collection of Preliminary Information
Collection of Preliminary Information
)(6
)(3
7.0
7.0
buildingsconcretewideorsteelHeavySD
buildingsconcretenarroworsteelLightSD
b
b
=
=
Foundation Design
Geotechnical Engineer
Where to sample
How deep to sample
What to sample
How to sample
Soil borings
Auger boring (Post hole and helical boring :
Wash boring
Scrapper bucket: sand mixed with pebbles
Clayey soils
Very soft soils
GEOLOGICAL MAP OF DELHI
AR
A
E
D
D
CC
BBG
G
FF
EK
JJ
I
I
H
H
MM
LL
K
R
Q
PP
OO
NN
Q
Soil Profiles of DelhiSoil Profiles of Delhi
Kakraula GaonSec-17
Dwaraka
Sec-12
Dwaraka Shahdra
Sec-7
Dwaraka
Filled up
soil
Sandy
silt
Silty
sand
Clayey
sand
Fine
sandQuarzite Gravely
sand
Depth
(m)
0
12
15
--13
--13
--22
--32
--9
--12
--11
--14
--10
--10
--42
--23
--30 --23
--14
--9
--9
--8
--21
--18
--27
--22
--23
--36
--30
--52
--50
--53
--23
--38
--14
--14
--16
--35
--38
--37
15 15
|--N
AA
Dayal Singh College,
Lodi roadElectric Cremation,
Lodi roadRing Road Jn
Filled up
soil
Sandy
silt
Silty
sand
Clayey
sand
Fine
sandQuarzite Gravely
sand
|--N
Depth
(m)
--20
--17
--11
--8
--24
--23
--44
--29
--100
--9
--3
--2
--4
--25
--12
--6
0
15
--7
--12
--7
--6
--19
--19
--34
CC
Sec-1,
NoidaSec-6,
Noida
Dallupura
Sewage Plant
Noida
Sec-61,
Noida
Sec-33,
NoidaSec-12,
Noida
Filled up
soil
Sandy
silt
Silty
sand
Clayey
sand
Fine
sandQuarzite Gravely
sand
|--N
Depth
(m)
--28
--20
--18
--19
--14
--32
--47
--12
--8
--6
--8
--7
--20
--16
--16
--11
--22
--20
--9
--9
--17
--21
--11
--15
--10
--8
--10
--20
--30
--20
--25
--7
--22
--21
--16
--64
--84
0
15
--10
--56
--15
--17
--18
--17 --53 --56
--22
--16
--5
--7
--8
--9
--6
--15
--39
--27
EE
Filled up
soil
Sandy
silt
Silty
sand
Clayey
sand
Fine
sandQuarzite Gravely
sand
|--N
Tilak
BridgeMandi
House C.P
Pusa
Road Patel
Road Punjab
BaghRohini
RL 208
176
216
212
208209
180
196
192
188
184
200
--51
--42
--26
--29
--45
--50
--38
--40
--23
--34
--45
--48
--60
--51
--37
--12
--10
--21
--63
--70
--61
--12
--40
--15
--20
--30--25
--30
--26
--75
--18
--28
--38
--22
--25--29
--42
--14
--26
--25
--30
--35 --30
--29
--12
--15
--17
--20
--37
--40
GG
Filled up
soil
Sandy
silt
Silty
sand
Clayey
sand
Fine
sandQuarzite Gravely
sand
|--N
Depth
(m)
ChanakyapuriB.D Marg
Lodi Road Golf LinksSarai Kale
Khan
Sec-1,
NoidaSec-62,
Noida
Sec-12,
Noida0
30
--39
--30
--14
--18
--21
--38
--34
--42
--39
--56--63
--25
--23
--35
--42
--19
--12
--26
--21
--25
--26
--29
--30
--18
--7
--10
--10
--15
--78
--22
--43
--46
--12
--26
--31
--26
--30
--42
--16
--18
--23
--31
--29
--13
--14
--28
--30
--19
--16
--8
--9
--25
--81
--13
--12
--14
--13
--20
--8
--10
--14
--15
--26
--34
--38
--77
--13
--17 --51
--55
--34
--34
--30
--39
--22
--32
--32
--25
--29
--32
--38
JJ
RL 208
180
184
200
196
196
188
204
Filled up
soil
Sandy
silt
Silty
sand
Clayey
sand
Fine
sandQuarzite Gravely
sand
|--N
208207208209
212
--49
--27
--3
--10
--57
--43
--34
--18
--7
--15
--36
--22
--20
--47
--100
--35
--27
--7
--11
--46
--36
--51
--32
--17
--21
--60
--35
--40
--36
--15
--17
--20
Sewanagar
Shahjahah
Road
Boat ClubN.D.Rly.Stn
Chawri Bazar ISBT
RR
GROUND WATER CONTOURS OF DELHI
DEPTH OF BED ROCK
SITE CHARACTERIZATION SITE CHARACTERIZATION
THROUGHTHROUGH
SEISMIC REFRACTIONSEISMIC REFRACTION
&&
MASW METHODSMASW METHODS
Seismic Refraction
Vertical GeophonesSource(Plate)
Rock: Vp2
ASTM D 5777
Soil: Vp1
oscilloscope
x1x2x3x4
t1t2t3t4
Note: Vp1 < Vp2
zR
Determine depthto rock layer, zR
Seismic Refraction
0.000
0.005
0.010
0.015
0.020 T
r
a
v
e
l
T
i
m
e
(
s
e
c
o
n
d
s
)
0 10 20 30 40 50
Distance From Source (meters)
Horizontal Soil Layer over Rock
Vp1 = 1350 m/s
1
Vp2 = 4880 m/s
1z
x
2 V V
V Vc
c p2 p1
p2 p1=
+
Depth to Rock:zc = 5.65 m
xc = 15.0 m
x values
t values
Wooden Hammer
Connecting Cables
PEG 40Kg
McSeis-SX48
Geophones
28Hz,& 4.5HzBattery
Base plate
Accessories
Seismograph with all Accessories
McSeis-SX48
Geophones
28 Hz
4.5 Hz
Connecting
Cables
Field Arrangements
Seismic Refraction
Source: Propelled Energy Generator (PEG-40)
Hammer Mass: 36 Kg
Hammer drop height: 36-43 cm
Motor: 12 Volt (requires car battery)
Output Frequency band: 10-250 Hz
(depends on ground conditions)
Weight assembled with shields: 113 kg.
05
10
15
20
25
30
35
0 500 1000 1500 2000 2500 3000
Vp (m/s)D
e
p
t
h
(
m
)
BMK
APS
SHL
D08
D22
0
5
10
15
20
25
30
35
0 200 400 600 800 1000
Vp (m/s)
D
e
p
t
h
(
m
)
D10
D05
D13
D16
D19
D20
0
5
10
15
20
25
30
35
0 300 600 900 1200 1500 1800
Vp (m/s)
D
e
p
t
h
(
m
)
DAP
JAP
TIJ
VIP
HAN
0
5
10
15
20
25
30
35
0 300 600 900 1200 1500 1800
Vp (m/s)
D
e
p
t
h
(
m
)
KIN
INP
KHY
WPB
PUV
1D Velocity Profiles
-85
-90
-95
-100
D
e
p
t
h
(m)
0 10 20 30 40 50 60(m)
Distance
Velocity Model at JNU Campus, Opp. Girls Hostel
(km/sec)
Vp0.300.540.791.031.28
Scale = 1 / 476
0.8
1.0
1.4
Velocity Profiles
- 7 0
- 8 0
- 9 0
- 1 0 0
D
e
p
t
h
( m )
0 1 0 20 3 0 4 0 5 0 6 0 7 0( m)
D i s t a n c e
J a n a k p u r i
( k m /s e c )
V p0 . 3 00 . 4 50 . 6 00 . 7 50 . 9 0
S c a l e = 1 / 1 0 0 0
- 7 5
- 8 5
- 9 5
D
e
p
t
h
( m )
0 1 0 20 3 0 4 0 5 0 6 0 7 0( m)
D i s t a n c e
D D A P a r k , M a y a p u r i
( k m /s e c )
V p0 . 3 40 . 6 30 . 9 3
S c a l e = 1 / 1 0 0 0
Velocity Profiles
VP at 40m depth
MASW
Source: wooden
hammer 11kg
Multichannel Records at JNU Site with Source Shifting along the Survey Line
0
10
20
30
40
50
60
-64 136 336
(a) at 69m (b) at 63m ( c) at 57m (d) at 51m (e) at 45m
(f) at 39m (g) at 33m (h) at 21m (i) at 9m (j) at 3m
05
10
15
20
25
30
0 200 400 600
Vs (m/s)D
e
p
t
h
(
m
)
BSF
JNU
VK1
VK2
NDV
0
5
10
15
20
25
30
0 200 400 600
Vs (m/s)
D
e
p
t
h
(
m
)
SHV
LSA
SAB
PVI
LAS
0
5
10
15
20
25
30
0 200 400 600
Vs (m/s)
D
e
p
t
h
(
m
)
TUF
GKII
LTE
JAS
NFC
0
5
10
15
20
25
30
0 200 400 600
Vs (m/s)
D
e
p
t
h
(
m
)
SIN
JNS
JAN
SAN
RKP
1D Velocity Profiles
2 0 1 5 1 0 5 0
D
e
p
t
h
( m )
7 1 7 2 7 3 7 4 7 5 7( m )
D i s t a n c e
J N U C a m p u s , O p p G i r l s H o s t e l
( k m / s )
V s0 . 3 00 . 3 60 . 4 20 . 4 8
S c a l e = 1 / 6 6 6
Velocity Profiles
2 5 . 0
1 5 . 0
5 . 0
D
e
p
t
h
( m )
9 . 0 1 9 . 0 2 9 . 0 3 9 . 0 4 9 . 0 5 9 . 0( m )
D i s t a n c e
D e f e n c e l a n d , s e c - 2 2 D w a r k a
( k m / s )
V s
0 . 2 00 . 2 50 . 3 10 . 3 6
S c al e = 1 / 66 6
Velocity Profiles
25 .0
15 .0
5 .0
D
e
p
t
h
( m)
3 .0 13.0 23.0 33.0 43 .0 53 .0 63.0( m)
Distan ce
Open ground opp to Nanadadevi Apts, Sec-10 Dwarka
(km/ s)
Vs
0.210.260.31
Scale = 1 / 66 6
Average Shear Wave Velocity Vs30 Map of Delhi Region
Down-hole/cross-hole tests
Down-hole/cross hole tests are in-situ test methods
- to measure dynamic soil/rock properties
- to determine P-wave and S-wave velocities
- to identify soil stratification
- to determine shear modulus, G =.vs
Surface source S-wave arrival time, t
Depth, z
Transd. 1Layer 1
Layer 2Transd. 2
vs = dz/dt
Down-hole Seismic test
Down-hole test
Source of impulse Receiver
Receiver Source of impulse
a) Down-hole test b) Up-hole test
Cross-hole test
Source ReceiverL
2 boreholes arrangement
Cross-hole test
SourceReceivers
L
3 boreholes arrangement
Down-hole testing
Downhole
TestingOscilloscope
Cased Borehole
x
Test
Depth
Interval
HorizontalVelocity
Transducers(GeophoneReceivers)
packer
PumpHorizontal Plank
with normal load
Shear Wave Velocity:Vs = R/t
z1z2
t
R12 = z12 + x2
R22 = z22 + x2
x
Hammer
By
Dr. Neelima Satyam D
Earthquake Engineering Research Centre
International Institute of Information Technology Hyderabad
Hyderabad-32
Email: neelima.satyam@iiit.ac.in; neelima.satyam@ gmail.com
GPR Demo Survey for utility
mapping at Habsiguda
Survey plan
GPR Data Collected
Plan of Utility Survey
10m x 5m
10mx 5m
Manhole 0.3m circularDia 200mm (Metallic)
Dia 600mm (Non-Metallic : RCC)
1st cable : bunch dia 40mm (network cables)
2nd cable single dia 60mm (High power cable)
3D Sectional view
Free Orbit View (sectional)
1st cable : bunch dia 40mm (network cables)
2nd cable single dia 60mm (High power cable)Dia 200mm (Metallic)
Dia 600mm (Non-Metallic : RCC)
0 m
1.0 m
0.7
0.9
0.75
0.19
0.19
0.940.93
0.88
0.82
3D View of Utility
Remarks
2 grids with 10m x 5m are made and surveyed
Two sets of cables (red colored) one in bunch (40mm dia) mostly it is
network cables and other running as single cable (60mm dia) which is
a high power cable are shown along with depths mentioned (slide 8)
One water pipe line (blue color) metallic with 200 mm dia was detected
with depths mentioned (slide 8)
Sewer pipe non-metallic (grey color) line with 600 mm dia was
detected with depths mentioned (slide 8)
Manhole invert levels are detected approximately at 2.2 m below GL
(since strata was highly saturated because of rain noise levels are
high)
Rain water collection chamber was also identified.
Plan of Utility Survey
Grid Size 20m x 8m
A B
DC
Road to Uppal
Divider
bunch dia 60mm
Dia 100mm (Metallic)
Optical fiber / telephone
1* Bunch of cables
Others are single
1*
A-1724'51"N 78 32'50"E
B- 1724'51"N 78 32'51"E
C-1724'51"N 78 32'51"E
D-1724'50"N 78 32'51"E
3D Sectional view
)(3.0
3.0
)(
2
SANDB
B
B
B
S
S
CLAYB
B
S
S
p
f
f
p
f
p
f
p
f
p
+
+=
=
PROCEDURE
. 30 cm diameter hole is trimmed where
the plunger is to be seated
Seating load of 4 kg is attached to the plunger
and dial gages reading is brought to zero
Results
Electrical resistivity method
L
RA=
Four electrodes at equal spacing, 2 will be used to send electric
current and 2 Which are inside will measure the voltage drop
between them
Report
Description of the scope of the investigation
Description of the structure
Site location (neighboring structures, drainage condition, veg type)
Geological settings
Details of field exploration (#, spacing, Db)
Type of soil profile
Lab tests
Water table details
Recommendations, limitations and conclusions of the investigation
Figures/graphs
Site map
Plan view of the exploration
Bore log details
Graphs corresponding to test data