Static Load Plate Test

ASHEGODA - CONSTRUCTION PHASERef.: SET-PHA2-CDS-1002

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Static Load Plate Test


Table of ContentsI. Plate test static deformation module (EV2):........................................................................................2

1. Standards and reference documents:..............................................................................................2

2. Objective:........................................................................................................................................2

3. Field of application:.........................................................................................................................2

4. Test equipments:.............................................................................................................................2

5. Principle of the test:........................................................................................................................3

6. Expression of the results:.................................................................................................................3

7. Interpretation:.................................................................................................................................3

8. Particular features and response time:............................................................................................3

9. Procedure........................................................................................................................................4

II. Test Plate-DUNOD Methodology-LCPL 1973 (EV2 and EV1):...............................................................6

1. Standards and reference documents:..............................................................................................6

2. Argumentation:...............................................................................................................................6

3. Procedure:.......................................................................................................................................6

4. Interpretation..................................................................................................................................7

Translation of ARVOR Géotechnique-“Portance des plates-formes”, chapter 3:................................7

Maximum values of k:..........................................................................................................................7

III. Appendix 1: “SETRA-US_0702-3A_Design_and_execution-F3 (Section 3-Test procedure)-sheet N°20” 8

IV. Appendix 2: ARVOR Géotechnique-“Portance des plates-formes”................................................10


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I. Plate test static deformation module (EV2):

1. Standards and reference documents: Reference standard:

NF P 94-117-1 “Sols: reconnaissance et essais-Portance des plates-formes-Partie 1 : Module sous chargement statique à la plaque (EV2)” (Soils : investigation and testing — Formation level bearing capacity — Part 1: Plate test static deformation module (EV2))

Reference book: SETRA-US_0702-3A_Design_and_execution-F3 (Section 3-Test procedure)-sheet N°20

2. Objective: This test enables the bearing capacity of a formation level to be determined by measurement of the ″Plate test static deformation module″.

3. Field of application: The test applies to formation levels of earthworks constructed with materials of which Dmax is less than 200 mm.

The maximum value of the EV2 module that can be measured by this test is 250 MPa.

4. Test equipments:It is defined by NF P 94-117-1.

VERGNET bought the full norm compliant set of equipments which is made of:

1 ø600mm reinforced steel plate 1 Bekelman beam 1 reference plate (attached to the beam) 1 hydraulic jack 1 ball-and-socket joint to fit with the reaction stand micrometer comparators

Additionally, the operators will use a chronometer


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5. Principle of the test: Measurement of the settlement of a rigid circular plate (ø600 mm diameter) transmitting a uniform pressure to the soil. The value of the settlement of the plate (measured at the end of the second cycle) enables the EV2 module to be determined.

6. Expression of the results:Using the Boussinesq equation, we find:

EV 2=90z2where{ EV 2∈MPa

90 isthe simplifiedexpressionof theBoussinesq equationwhenapplywiththe test data( french standard) ,

z2is settlement of the plate caused by the 2nd loading∈mm

:

7. Interpretation: For example, for earthwork sub-formation levels, GTR (French road earthwork manual) uses a minimum value of 20 MPa, or 35 MPa in the case of a treated subgrade being formed.

For roadway support formation levels, and on standard sites, a minimum EV2 module of 50 MPa is used, to enable the construction of the roadways. Higher values may be required, depending on the category of formation level, if it is considered that they are representative of the long-term bearing capacity.

This module does not characterize the state of compaction of the soils of the formation level being examined.

8. Particular features and response time: A reaction base is needed that can enable at least 8 t to be applied to the plate, and with support points located more than 1.20 m from the centre of the loading plate.

Timescale: 15 to 30 min, depending on the speed of stabilization.


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9. Procedure1) Preparing the platform and the equipment:a) Removing dust layerb) Flattening the platform with a ø800mm disk of sand as thin as possible for the plate.c) Flattening the platform for the reference point of the Bekelman beam with sand.d) Setting the equipments.e) Aligning the reaction stand above the jack (truck).f) Rising the jack until touching without pressure the truck. 2) In 30s minimum, a first load (7,068 daN±140) is applied on the plate;

The resulting average pressure on the platform is 0.25 Mpa.3) When this pressure is reached, keep applying it till the stabilization of the platform deflection.

The definition of stabilization is a settlement less than 0.02 mm /15s. 4) Reset the load in a delay less than 5s. And Write down the persisting settlement as Z0. Or reset

the comparator to zero.5) With the same loading speed as in 1), apply the second load (5,654 daN ± 110).

The resulting average pressure on the platform is 0.20 Mpa.6) As in 2), maintain the pressure until stabilization.7) Write down the settlement Z1. Note: depending on the choice to reset the comparator to zero or

to write down Z0, Z2 will be the Z1 or (Z1-Z0).8) Reset the load to zero.

9) Assuming the plate test equipment is as per the standard and as International Unit System is used, the Boussinesq formula give EV2 as :

EV 2=90z2where{ EV 2∈MPa

90 isthe simplifiedexpressionof theBoussinesq equationwhenapplywiththe test data( french standard) ,

z2is settlement of the plate caused by the 2nd loading∈mm


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Figure 1 Loads and Measured Settlements

Settlements during stabilization

e1


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II. Test Plate-DUNOD Methodology-LCPL 1973 (EV2 and EV1):

1. Standards and reference documents: Reference standard:

NF P 94-117-1 “Sols: reconnaissance et essais-Portance des plates-formes-Partie 1 : Module sous chargement statique à la plaque (EV2)” (Soils : investigation and testing — Formation level bearing capacity — Part 1: Plate test static deformation module (EV2))

Reference book: SETRA-US_0702-3A_Design_and_execution-F3 (Section 3-Test procedure)-sheet N°20

Reference book: LCPC-“Essai à la plaque-Dunod”-1973

ARVOR Géotechnique-“Portance des plates-formes”

2. Argumentation:The NF P 94-117-1 norm doesn’t define a name and use the value of the first load at 0.25 MPa.

The SETRA-US_0702-3A_Design_and_execution-F3 (Section 3-Test procedure)-sheet N°20 in its French version clearly state that the static plate test doesn’t provide a compaction measurement.

Nonetheless, comparing the settlement of the first load to the one of second load permits the appreciation of the compaction quality if not measurement. It is the scope the LCPC-“Essai à la plaque Dunod-1973” which procedure and conclusion are summarized in ARVOR Géotechnique “Portance des plate-formes” Chapter 3.

3. Procedure:It is the same as for determining EV2

An additional record is made by writing down e1, the settlement after the first load (at 7,068 daN).

Then EV1 is given by:

EV 1=112.5e1

where{ EV 1∈MPa112.5 is the simplified expressionof theBoussinesqequation

whenapplywiththe test data ( frenchstandard ) ,e1 is settlement of the platecaused by the 2nd loading∈mm


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4. Interpretation

Translation of ARVOR Géotechnique-“Portance des plates-formes”, chapter 3:This test methodology also interprets the first loading.

In fact, the value of EV1 characterizes the deformability of an embankment in its actual state.

Assuming that the Poison coefficient is 0.25, EV1 is given by the simplified Boussinesq equation here above.

A low EV1 value may be the result of:

a lack of compaction. a qualitative poor material. a compacted material with too much moisture content.

Consequently, the EV2 modulus permits the appreciation of the platform deformability after a series of loads.

If the initial compaction is defective, one will notice a significant reduction of deformability / settlement.

The ratio k=EV 2EV 1

is a characterization of the compaction quality; a lower k reveals a better

compaction quality.

Maximum values of k:Depending on the country, the materials, and the purpose of the platform k values range from 1.8 to 2.5.

In ARVOR Géotechnique-“Portance des plates-formes”, chapter 3:, there is the table here under.

Class of Materials EV2 (Mpa) k

D >100 2.5

A & B >50 2

In summary, A & B class of materials regroups materials with fine content while D class is for materials without fine content and/or insensible to moisture.

In the case of ASHEGODA Wind Farm Project, VERGNET will keep the safest value k=2.

Note: if this value of k seems too low for high value of EV2 (>100MPa), by checking compaction test results, VSA may reconsider the value of k to 2.5.


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III. Appendix 1: “SETRA-US_0702-3A_Design_and_execution-F3 (Section 3-Test procedure)-sheet N°20”


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IV. Appendix 2: ARVOR Géotechnique-“Portance des plates-formes”


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Static Load Plate Test

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