report si before soil improvement

8/12/2019 Report SI Before Soil Improvement

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1. GENERALSUMMARY OF THE WORKS

4.1 Boring4.2 Sampling4.3 Standard Penetration Tests4.4 Vane Shear Tests4.4.1 Scope of vane shear test4.4.2 Quantities of vane shear test4.4.3 Specification of equipment4.4.4 Procedure

4.5. Electrical Cone penetration test (CPTu) and Dissipation test4.5.1 Quantities of CPTu and dissipation test4.5.2. Equipments4.5.3. Procedure

6. SOIL INVESTIGATION RESULTS6.1 Site Condition6.2 Subsurface profile6.3 Vane Shear test results

6.4 Electrical Cone penetration test resultsGround water condition table.22


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1. GENERAL

- This report presents results of the geotechnical investigation for The 2x600MW Long Phu 1 Coal fired Power Project in accordance with the Contract

No.018-2011/PTSC-BDALP/HD signed on 24th

January 2011 betweenPetroVietnam Technical services Corporation (PTSC) and Fecon-Shanghaiharbour J.O.

- The project site is located in Long Duc Commune - Long Phu District - SocTrang Province.The Geotechnical Investigation Work of the Project shall be carried out tocollect additional geotechnical data of subsoil before soil improvement work.

SUMMARY OF THE WORKS

The works were implemented according to approved method statement in orderto provide sufficient detail data of soil properties and layers for assessing of softsoil improvement work and for designing foundations.The field works were commenced on 17 th January 2011 and completed on 14 th

Fbruary 2011. Summarized of the works is shown on below Table 1.

Table 1: Summarized Quantities of the works

No. WORK ITEMS UNIT Quantity

A FIELD WORKS

1 Setting out borehole, CPTu nos. 102 Rotary Wash Boring(6 boreholes x 30m/hole) m 180

3 Standard Penetration Test (SPT) nos. 91

4 Vane Shear test (2m interval) point 38

5 Cone Penetration Test (CPTu)(4 CPT x30m) m 120

6 Dissipation test nos. 12

7 Sampling Sample 90

B LABORATORY WORKS8 Undisturbed sample tests Sample 41

9 Unconsolidated Undrained Triaxial Compression Test(UU) Sample 12

10 Consolidated Undrained Triaxial Compression Test (CU) Sample 06

11 One Dimensional Consolidation Tests Sample 12


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Table 2: Detail quantity of works in each borehole

- TCXDVN 194:2006 High rise building - guide for GeotechnicalInvestigation;

- TCVN 4419:1987 Investigation for construction - principal fundamental;

- TCXD 160:1987: Geotechnical Investigation for designing and executingpile foundation;

- TCXD 45-78: Standard of designing foundation and project;- 22 TCN 259:2000: Procedure of drilling in geology survey;- 22 TCN 262:2000: Procedure of Investigation and design of the motorway

embankment on soft soil;

- ASTM D1586: Standar test method for standar penetration test of soil (SPT);- ASTM D2573: Standar test method filed vane shear test in cohesive soil

(VST);- ASTM D5778: Standard Test Method for Performing Electronic Friction

Cone and Piezocone Penetration Testing of Soils (CPTu);

- ASTM D2216: Determination of Moisture Content;- ASTM D4318: Determination of Atterberg Limits;- ASTM D854: Determination of Specific Gravity;- ASTM D422: Determination of Particle Size Distribution;- ASTM D4253: Unit weight;- ASTM D2850: Unconsolidated Undrained Triaxial Compression Test (UU);- ASTM D4767: Consolidated Undrained Triaxial Compression Test (CU);- ASTM D2435: One-Dimensional Consolidation Test


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- TCXD 226:1999 Soil for building - In - situ testing - Standard Penetrationtest;

- 20TCN 74:87 Soil for building - The method of statistic analysis in results of soil properties;

- ASTM D1587: Standard of thin wall tube sampling for geotechnicalpropose;

- ASTM D2488: Standard Practice for Description and Identification of Soils.- TCVN 5308-91: Vietnames Code for Safety Technic in Construction.

4.1 Boring

- Borehole shall be carried out in accordance with ASTM D2113.- Wash drilling method shall be applied with betonies liquid, diameter of

borehole shall be at least 91mm. If necessary, casing pipe shall be used toprevent collapse of bore-wall.

- Description of soil during drilling work shall be in accordance with ASTMD2488.

- The limitation of borehole depth shall be followed requirement for soft soiltreatment. The depth of borehole consists of 30 m for all boreholes.

- If sand lens is met, SPT is performed with 1m interval.Sand lens section have tobe determined and ploted in layout of project plan.

- Measuring groundwater level after finishing drilling work for each borehole.- Drilling was implemented on this site using a XY-1 drilling rig Made in China

with the following technical specifications:Diameter of borehole 75-150 mmRotation speed 150-650 R/min.Hydraulic capacity 2.0 TonMax. compressive pressure 1.5 TonMax. drilling depth 100 m

- Procedure of drilling process shall be done as orders bellow:Mark the drilling location, confirm the Coordinate and Elevations.

Check the drilling location according to plan.Take photographs of the site together with the drilling rig in position.Use Appropriate Drilling Bit or equivalent cutting bit.Level Drilling RigCenter Drilling Rod before drilling (Important for coring).Mark on drilling rod the required drilling depth.Drill to required depth, flush the hole with water until the bottom is clean.Use Bentonite if Sand particles cannot be lifted.Use Bentonite if the hole collapsed.


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- All detail Boring results are presented in the log of the borehole in Appendix 2.

Picture 1: Boring

4.2 Sampling

- Prior to sampling the bottom of the borehole was cleaned by pressured water.- Undisturbed samples were carried out in all boreholes with every 2m interval

and instructed directly by the Engineer (alternatively with SPT). The opensampler shall be used for stiff clay and the thin walled samples must be used forsoft organic clay. Minimum sample diameter to be used must be 60cm andminimum sample length must be 20cm.

- Disturbed samples were recovered in split spoon sampler (from SPT) with aspacing of every 2.0m.


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Picture 2: Sampling

4.3 Standard Penetration Tests

- Standard penetration tests - SPT and split - barrel sampling of soil were carried

out in the boreholes in accordance with ASTM D1586.- For the standard penetration tests a 51mm diameter thin-wall split barrel

sampler was used, which was driven down into the bottom of borehole by usinga 63.5kg hammer with a high of fall of 760mm. The number of blow (N)required to drive the sampler down to 30cm was counted discounting the first15cm. This N value (Blows/30cm) is so-called the penetration resistance of thesoil. The N value was recorded and presented in the boring logs. The testingwas conducted at 2.0m intervals when encountered medium soils or as directedby the Engineer.

- The samples collected from the split-barrel sampler were checked carefullythen kept in plastic bags and labeled as disturbed samples and placed in woodenboxes

- All detail SPT results are presented in the log of the borehole in Appendix 4.


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Picture 3: Standard Penetration Tests

4.4 Vane Shear Tests

4.4.1 Scope of vane shear test- The test was carried out according to ASTM D 2573 Standard.- This test method covers the field vane test in soft, saturated, cohesive soils. The

vane shear test basically consists of placing a four-bladed vane in theundisturbed soil and rotating it from the surface to determine the torsional forcerequired to cause a cylindrical surface to be sheared by the vane; this force isthen converted to a unit shearing resistance of the cylindrical surface.

- Vane shear test is performed inside boreholes. During the test, record undrainedshear strength at both nature and failure state are recorded at the different depth.

The soil sensitive characteristics are calculated based on the test results.4.4.2 Quantities of vane shear test

Table 3: Summary of vane shear test quantities

No. Test number Max. depth of

testing, m

The number of

Vane shear testing

1 A-VST 01 17.2 7


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2 A-VST 02 15.2 6

3 A-VST 03 14.2 6

4 A-VST 04 15.2 6

5 A-VST 05 15.2 7

6 A-VST 06 13.2 6

Summary 90.2 38

4.4.3 Specification of equipment- Testing equipment: Geonor H-70 (Made in England). Serial number: B040705- Vane size (D/H): 60mm/120mm- Load cell for measuring torque has maximum capacity of (0 16)ton/m2. It can

be measured undrained shear strength with vane diameter of 60mm.4.4.4 Procedure

- Undrained shear strength is determined from Vane shear test for soft soil layersto provide data for designing requirement.

- Vane shear test is performed inside boreholes. During process of shearingrecord, recode undrained shear strength at both nature and failure statefollowing the different depth. Testing results is based to calculate soil sensitivecharacteristics.

- Test is applied with rotary speed rate of vane 0.1degree/second (0.10/s)

- Value is recorded concretively until max value.- The test is performed at both nature and failure static

Picture 4: Vane shear Test


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4.5. Electrical Cone penetration test (CPTu) and Dissipation test

- The CPTu and Dissipation test were carried out according to ASTM 5778.

4.5.1 Quantities of CPTu and dissipation test

Table 4: Quantities of CPTu and dissipation test

No. Name test Depth of testing, m The number of dissipation of pore

water pressure

Remarks

1 A-CPT 01 30 3

2 A-CPT 02 30 3

3 A-CPT 03 30 3

4 A-CPT 04 30 3

Summary 120 12

4.5.2. Equipments

The required field test apparatus that made in Netherlands is as follows:

CPT rig with engine/pump unit and the reaction system can be achieved to a

maximum of 150kN;Electronic cone: C10CFIIP type;

Push/pull clamp with proximity switch;

Sounding tube: Ext. diameter of 36mm, int. diameter of 16mm, length of

1000mm;

Sounding cable: standard or with interconnector, diameter of 8,8mm; length

of 50m;

Data acquisition system: GME500 IP65 type;

Computer with CPT test and CPT task software;Miscellaneous Tools


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Picture 5: Electrical Cone penetration test

4.5.3. ProcedureA penetrometer tip with a conical point having a 60 apex angle and a cone

base area of 10 cm 2 is advanced through the soil at a rate of about 20

5mm/s. The force on the conical point (cone) required to penetrate the soil is

measured by electrical methods, at a minimum of every 10 mm of penetration. Stress is calculated by dividing the measured force (total cone

force) by the cone base area to obtain cone resistance, qc.

A friction sleeve is present on the penetrometer immediately behind the cone

tip, and the force exerted on the friction sleeve is measured by electrical

methods at a minimum of every 10 mm of penetration. Stress is calculated

by dividing the measured force by the surface area of the friction sleeve to

determine friction sleeve resistance, fs.

Penetrometers are capable of registering pore water pressure induced during

advancement of the penetrometer tip using an electronic pressure transducer.

These pen etrometer are called piezocones. The piezocone is advanced at a

specific rate, and readings are taken at a minimum of every 10 mm of

penetration. The dissipation of either positive or negative excess pore water

pressure can be monitored by stopping penetration, unloading the push rod,


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and recording pore pressure as a function of time. It is frequently

recommended that the dissipation be continue until to at least U = 50%. The

degree of dissipation (U) is determined as following [3]:

%100

0

0

uu

uuU

i

t

Where:

ut: pore pressure at time t;

u0: equilibrium pore pressure in situ;

ui: pore pressure at start of dissipation test or Max. pore pressure.

Checking before starting a CPT test:

Check if sounding rig and motor/pump unit are working properly;Check if CPT acquisition software is installed on the computer;Check if the depth encoder is properly installed;Check if proximity switch on the push/pull clamp is in proper condition.Prepare the cable, tubes and cone and saturation of a piezocone for CPTu.

GME500 IP65 cabling:

Position the GME500 IP65 facing the front;Connect the 110/230Vac or 12/24Vdc to the GME500 IP65;Connect the depth encoder cable to the connection box and GME500 IP65;Connect the proximity switch cable to the connection box and push/pullclamp, or pressure head;

Connect the depth/alarm cable to the connection box and GME500 IP65;Connect the sounding cable to the front of the GME500 IP65. In this case, a10 pin lemo is plugged into the 10 pin connector.Connect the computer to the GME500 IP65, using the interface cable;Connect the computer cable to the appreciate serial port of the computer;Switch on the main power supply.Starting a CPTu test:

Switch on the computer;Start the CPTu acquisition software: To start the program, open the Startmenu, choose Programs and then the folder where you have installed CPTtest. Then click on CPTest, and the program will be started.Before starting CPTu test, the Zero values are displayed. Now theprogram will proceed to record an actual calibration the cone or measuringhead. This means that outputs of the cone/measuring head will besynchronized to a load of zero. The calibration process is completed whenthe bar is completely blue. If the current values deviate too much from thezero values in the calibration data, the program will produce an errormessage. If the calibration process runs without problems, the program willautomatically start the sounding screen.


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4.6 Ground water Monitoring

The underground water level was monitored in the borehole during drilling

operation and after completion of drilling. Stable data was recorded.

All the laboratory tests shall be carried out by testing equipment followingexisting standard which are originated and transferred from USA, Japan,

West European Countries, Russia and China.

Laboratory soil tests were carried out in the laboratory of Center for lab for

the south of Vietnam (LAS-XD261). The lab test requirements were

instructed by the Engineer.

The following laboratory soil and water tests were performed:

ASTM D2216: Moisture Content;ASTM D4318: Atterberg Limits;ASTM D854: Specific Gravity;ASTM D422: Particle Size Distribution;ASTM D4253: Unit weight;ASTM D2850: Unconsolidated Undrained Triaxial Compression Test (UU);ASTM D4767: Consolidated Undrained Triaxial Compression Test (CU);ASTM D2435: One-Dimensional Consolidation TestThe details of tests were shown in the Appendix 7

6. SOIL INVESTIGATION RESULTS

6.1 Site ConditionThe existing site levels of Project is +1.00m to +3.08m in elevation. The

locations of soil investigation points are shown on Appendix 1.

6.2 Subsurface profile

The subsurface profile encountered in the investigated site is shown in boreholelogs, geological section drawings and described below:

a) Layer 1: Fill sand: fine sand, brownish grey, yellowish grey, loose. This layerdistributes on the ground surface. The elevation of top layer is +1.00m (A-

LP06) to +3.08m (A-LP03). The thickness is varies from 1.0 m (A-LP05) to 3.5m (A-LP01), average thickness is 1.92m. SPT value in average N = 6.5 blows.

b) Layer 2a: (CH): Fat clay, brownish grey, yellowish grey, firm. SPT value inaverage N = 7. This layer encountered in three boreholes (A-LP02, A-LP03, A-LP04). The begining depth of the layer varies from 1.3m (A-LP04) to 2.2m (A-LP02). The completed depth of the layer varies from 3.0m (A-LP03) to 3.7m(A-LP02). The average thickness is 1.43m.


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Table 5: Summary of soil test results in soil layer 2a

Soil Properties Symbol UnitValue

Average Max Min

ParticleSize(mm)

Coubble >75.0

P %

Gravel Coarse 75.0-19.0Fine 19.0-4.75

SandCoarse 4.75-2.00Medium 2.00- 0.425 2Fine 0.425-0.075 3

Silt0.075-0.02 320.02-0.005 18

Clay 75.0

P %

GravelCoarse 75.0-19.0Fine 19.0-4.75

SandCoarse 4.75 2.00Medium 2.00 0.425Fine 0.425 0.075 3

Silt0.075 0.02 410.02 0.005 13


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Clay 75.0

P %GravelCoarse 75.0-19.0Fine 19.0-4.75

Sand Coarse 4.75-2.00


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Medium 2.00-0.425 1Fine 0.425-0.075 11

Silt0.075-0.02 440.02-0.005 11

Clay


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Table 8: Summary of vane shear test result

Vane shear testnumber

Depth(m)

Undrained shearstrength at naturestatic, Su (kPa)

Undrained shearstrength at failure

static, Sr (kPa)

VST01

5.2 9.1 1.87.2 9.1 1.89.2 9.1 1.8

11.2 13.7 4.613.2 14.6 4.615.2 15.5 2.717.2 17.3 3.6

VST02

5.2 7.6 1.87.2 8.7 1.9

9.2 10.9 4.211.2 14.5 3.613.2 13.2 3.315.2 13.9 4.0

VST03

4.2 8.4 2.56.2 8.3 2.78.2 9.6 2.7

10.2 11.8 2.912.2 12.6 2.714.2 12.3 3.2

VST04

5.20 7.7 2.77.20 8.7 2.99.20 10.1 3.9

11.20 10.1 3.613.20 11.2 3.515.20 11.5 2.6

VST05

3.20 8.2 2.75.20 9.1 2.77.20 9.6 2.79.20 10.9 2.5

11.20 10.0 3.213.20 11.8 2.615.20 11.6 3.2

VST06

3.20 8.4 3.25.20 8.2 2.77.20 9.1 3.29.20 10.9 2.7

11.20 10.0 2.313.20 11.8 3.6


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6.4 Electrical Cone penetration test results

The CPTu test was carried out for 04 location, namely A-CPT01 to A-CPT04, and

results were shown on the attached plots with the following information:

Location of test and test reference number;

Data and time of start and finish of test;

Ground level and coordinates;

Plot of cone point resistance versus of depth;

Plot of local sleeve friction (f s) versus of depth;

Plot of pore pressure (u 2) versus of depth;

Plot of friction ratio (f s /qc) versus of depth;

Numerical values q c, f s, and u at depth of intervals of 5cm

Soil profile based on interpretation of the CPT data.

- The cone resistance, q cThe cone resistance, q c, is the force per unit area which is obtained by dividingthe total axial force acting against the tip by the cross section area of the tipbase (A T = 10 cm

2)

T

T c A

F q (MPa)

The corrected cone resistance, q t2)1( uqq sct (MPa)

- The sleeve friction, fs

The sleeve friction, f s is obtained by dividing the total friction force actingaxially on the friction sleeve by the outer surface area of the sleeve, A s = 150cm 2.

s

ss A

F f (MPa)

- Friction Ratio, Rf The friction ratio is the ratio between the sleeve friction and the cone resistanceat the actual level.

(%)100t

s f q

f R

- Soil classification

Soil classification based on the friction ratio and/or the chart of Robertson and


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others (1986) of pore pressure ratio, B q and the corrected cone resistance, q t(Table 9).

Table 9: Soil classification based on the pore pressure and the cone resistance

Zone Soil type Zone Soil type Zone Soil type

1 Sensitive finegrained 5Clayey silt tosilty clay 9 Sand

2 Organic material 6 Sandy silt toclayey silt 10Gravely sand tosand

3 Clay 7 Silty sand to siltyclay 11Very stiff finegrained

4 Silty clay to clay 8 Sand to silty sand 12 Sand to clayey sand

Fig. 1- Soil classification based on q t and B q (Robertson et al., 1986 )

Calculate the coefficient of consolidation C h based on data of the dissipation of pore water pressure

From the data of the dissipation of pore water pressure, calculate the coefficient


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of horizontal consolidation of soil, Ch based on the Houlsby and Teh formula(1988) as following [4]:

2

0

50

*

50r

T

I T C r h

Where:T *50: Modified time factor is found from the Houlsby and Teh solutions, fromtable 5.10 [4], chosen T *50 = 0,245 ;r0 : Penetrometer radius, r 0 = 0,0178m;

Ir: Rigidity index, G/S u, from figure 3.56 [4], determined I r = 66,7.T50: The measured time for 50% dissipation;

The calculated results of the coefficient of consolidation C h for the soils arelisted in the table 10.

Numberof CPTu Depth

Max.pore

waterpressure

Initialpore

waterpressure

The time of dissipation

50%

Coefficient of consolidation

Soil type(based on

CPT)

H, m u i, MPa U 0, MPa T 50 , s C h, 10-4cm 2 /s

CPTu 01

6,0 0,181 0,030 3256 19,47 Soft clay

10,0 0,318 0,707 946 67,00 Soft clay

14,0 0,364 0,110 795 79,75 Soft clay

CPTu 02

5,0 0,098 0,020 5026 12,62 Soft clay

9,0 0,245 0,060 2296 27,62 Soft clay

13,0 0,326 0,100 1216 52,13 Soft clay

CPTu 03

6,0 0,150 0,050 3985 15,92 Soft clay

9,0 0,153 0,080 795 79,75 Soft clay

12,0 0,190 0,110 855 74,14 Soft clay

CPTu 04

4,0 0,132 0,030 4875 13,00 Soft clay

8,0 0,287 0,070 1845 34,37 Soft clay

12,0 0,347 0,110 975 65,04 Soft clay


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6.5 Ground water condition table

The underground water level was monitored in the hole during site construction

time and after completion of drilling. Stable water level is Elevation (EL)+0.7m

to Elevation (EL) +2.23m

Table 11: Water level at borehole and CPT

No Borehole No Depth (m)Ground

water level(m)

1 A-LP01 1.0 2.022 A-LP02 0.8 2.233 A-LP03 0.9 2.184 A-LP04 1.0 2.045 A-LP05 0.3 1.2

6 A-LP06 0.3 0.7

According to the above results of the soil investigation, the recommendation is asfollows:

Soil layer 1 is fill sand layer.

Soil layer 2a is firm, with small capacity and medium deformation.

Soil layer 2 is very soft with very small capacity and high deformation.

Soil layer 3 is stiff to very stiff with quite high capacity and mediumdeformation.The 2x600 MW Long Phu 1 Coal fired Power Project has included so many itemsconstruction and different capacity.For structures with light load, shallow foundation should be only constructed aftersuitable soil treatment and consolidation methods.For structur es with heavy load, piled foundation should be applied, piles size andlength should be calculated based on each location and load on its foundation.

This report has been completed in accordance with requirements of design for SoftSoil Improvement.The investigation result shown that the proposed site condition is comfortable forconstruction of Project.For structures with light load, shallow foundation should be only constructed aftersuitable soil treatment and consolidation methods.For structures with heavy load, piled foundation should be applied, piles size andlength should be calculated based on each location and load on its foundation.


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However, pile toe penetrating into Layer 3 should be the best pile option for heavystructures.However, the Design Engineer shall choose the most appropriate foundation optionfor each location structure of the Project depending on calculating load of thestructures on bearing foundations.

APPENDIX 1: Location of Investigations PointsAPPENDIX 2: Borehole LogsAPPENDIX 3: Summary table of soil properties by layers (all tested soil samples)APPENDIX 4: Geological Section DrawingAPPENDIX 5: Details of Vane Shear Test ResultsAPPENDIX 6: Details of Cone penetration test results (CPTu)APPENDIX 7: Details of Laboratory Test Results

report si before soil improvement

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