Geo Tech Natural Gas

7/25/2019 Geo Tech Natural Gas

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A Geotechnical Investigation Report

For

Proposed Natural Gas Pipeline Dia 16 inch

Client. -MM

Consultant.Petro Chemical Engineering Consultant

EPC Contractor. Petro Con Pvt.Ltd

May, 16, 2015

Geo Tech Report prepared byPEC Licence # 41987

House no-19 Mah-e- Nor Vills Nisheman Iqbal Lahore.042-35228238

An overview

The Geo technical Investigation Report prepared by GDE for Natural Gas Pipeline of FFC focuses on the

various Geotechnical aspects such as computation of safe bearing capacity, review of site condition


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Geo Drillers Engineering (GDE)

Natural Gas Pipeline 16 inch diaNo. 1

SUBSURFACE INVESTIGATION AND LABORATORY TESING FOR THEProposed Natural Gas Pipeline dia 16 inch

TABLE OF CONTENTS

1.0 Introduction 2

2.0 Purpose and scope of work 3

3.0 Field investigation 4

3.1 Drilling of boreholes 4

4.0 Laboratory testing. 5

4.1 Soil classification tests

4.2 Specific gravity of soil 54.3 Unit weight 5

5.0 Results of the investigation 7

5.1 The subsurface strata 7

5.2 Groundwater conditions 7

6.0 Geotechnical parameters 7

6.1 Unit weight 7

6.2 Shear strength parameters 76.3 Modulus of elasticity (es) 9

6.4 Selection of foundation type 9

6.5 Depth of foundation 9

6.6 Allowable bearing pressures 10

6.7 Guidelines for placing the foundations 11

SEPERATORS


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1. INTRODUCTION

Geo Drillers Engineering (GDE), was engaged by the Petro chemical

Engineering Consultant, to carry out a subsurface soil investigationcampaign at the site of Proposed natural Gas pipeline. This report pertains

to the project a brief description of the geotechnical tasks performed at site

as well as results of the insitu field and laboratory tests. The report

presents an assessment of the general geotechnical conditions at the

investigated site. Specific recommendations for the foundation design are

included in this report.

The investigation was performed in accordance with the scope of work

stipulated by the client and comprised several tasks that included drilling of

boreholes to the designated depths below the existing ground level, in-situ

testing and sampling of the sub-soil through standard penetration tests

(SPTs) at different depth horizons, laboratory analysis. The scope of GDE

services also included preparation of a geotechnical report describing the

methodology and presenting results of all the geotechnical investigation,

recommendations for foundation design.

This report contains the results of field & laboratory investigation and a

brief description of the techniques employed during the field works as well

as methods used in performing the laboratory tests.

The evaluation of geotechnical parameters together with recommendations

for foundations and geotechnical work related to design & construction of

foundations is also included in this report.

The borehole logs and laboratory test results are presented in APPENDIX

respectively.


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2. PURPOSE AND SCOPE OF WORK

The purpose of the present investigation was to assess the prevailinggeotechnical conditions at the site and to verify the geo-engineering

properties of the deeper subsurface soil strata which will significantly affect

the foundations behaviour. The field investigation program comprised of

the following:

1. Drilling and sampling of a total of six (6) boreholes were drilled down

to a depth 10.0 m from surface level at the different locations

designated by the consultant.

2. In-situ testing and sampling of overburden soil by performing Standard

Penetration Tests (SPTs) at each1.0 m from surface down to maximum

borehole depth.

3. Conducting necessary laboratory tests on selected soil samples

retrieved from the boreholes.

4. Preparation of a geotechnical report presenting the investigation

procedures and the results of the in-situ and laboratory tests together

with recommendations for foundations design and construction.


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3. FIELD INVESTIGATION

A total of six (6) boreholes were drilled at site down to a depth 10.0 m from

surface level. The borehole logs are presented in APPENDIX-A.

3.1 DRILLING OF BOREHOLES

The drilling at each borehole location was carried out using percussion

drilling method. Drilling was carried out through a 5 hollow stem auger,

using augering method. The Standard Penetration Tests (SPTs) were

performed at surface and thereafter at a depth interval of 1.0 m in

accordance with ASTM D1586. The drive assembly of SPT consisted of

hammer of 140 lb. weight, a driving head and a guide permitting free fall of

30 inch. The assembly was equipped with split spoon sampler to collect the

disturbed samples for necessary identifications and testing. The samples

retrieved from the split spoon sampler were examined for their visual

identification, packed in airtight polyethylene bags and sent to the

laboratory for further evaluation and testing. A record of field observation

was maintained in the form of field logs describing the visual identifications

(ASTM-2488) of the subsurface materials encountered at different depths,

the sampling details and recording the blow count observed in the SPT.

These logs were later on refined by incorporating the laboratory test results

and are presented in APPENDIX-B.


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4. LABORATORY TESTING

Representative soil samples retrieved from the split spoon sampler (SPT)

were selected from each borehole. The representative SPT samples weretested in laboratory. The SPT samples were subjected to moisture content,

gradation and Atterberg limits in order to identify the subsurface materials.

The tests were performed according to relevant American society for

testing Materials ASTM. The laboratory test results are presented in

LABORATORY TESTING separator.

4.1 SOIL CLASSIFICATION TESTS (ASTM D422)

The classification test performed on selected representative samples of

subsurface materials consisted of determination of natural moisture

content (ASTM D2216), Liquid Limit and Plastic Limits (ASTM D4318) and

Grain-size Analysis (ASTM D422) and sedimentation test by Hydrometer

(ASTM D4221-99).

4.2 SPECIFIC GRAVITY OF SOIL (ASTM D 854-06)

Specific gravity tests were performed on selected representative samples of

subsurface materials according to (ASTM D854-06).

4.3 UNIT WEIGHT (AASHTO T233-02)

The soil samples retrieved from the boreholes were subjected to density

measurement according to AASHTO T233-02 measuring the weight and

volume by immersion in water.


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Measurements of soil properties in the Laboratory in Table-1 lists various

laboratory tests on Un disturbed and disturbed samples soil samples

collected from various depths to find physical properties and strength

characteristics.

Table 1 Measurements of soil properties

Sr.No Tests Performed

procedure

Type

sample

1 Sample preparation ASTM(D 2487) DS/UDS

2 Moisture content ASTM(D 2216) UDS

3 Dry unit weight ASTM(C 29) UDS

4 Specific Gravity ASTM(D 854 & C127) UDS

5 Grain size Analysis ASTM(D 422) DS/UDS

6 Direct shear test ASTM(D 3080) UDS

7 N- observed ASTM(D 2166) DS

8 Unconfined

compressive Strength

ASATM(D2166) UDS

9 LL & PL ASTM (D422) DS


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5. RESULTS OF THE INVESTIGATION

5.1 THE SUBSURFACE STRATA

The description of the subsurface soil strata is based on the inspection of

soil samples retrieved from the field and later refinements done after

laboratory test results. Based upon the results of the field investigation a

representative subsurface soil profile has been developed described as

follows:

Near Railway Track Change=14 +275

BH.no Layer

Encounter

Type of

soil

SPT-N

value

Layer

Up to

Total

thickness

1

Layer-1 SM 1~3 0~2.0 m 2 m

Layer-2 CL 3~5 2~7 m 5 m

Layer-3 ML 3 7~8 m 1m

Layer-4 SM 7~11 8~10 m 2 m

Groundwater was encountered at 1 m depth in the 1stweek of May 2015

Near Masu Wah Canal Change=13 +650

BH.no Layer

Encounter

Type of

soil

SPT-N

value

Layer

Up to

Total

thickness

2

Layer-1 CL 1~3 0~3.0 m 3 m

Layer-2 SM 4~6 3~8 m 5 m

Layer-3 SP-SM 7 8~10 m 2m



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Near Canal Road Crossing Kandyaro change=10 +775

BH.no Layer

Encounter

Type of

soil

SPT-N

value

Layer

Up to

Total

thickness

3

Layer-1 SM 5 0~3.0 m 3 m

Layer-2 SP 1~3 3~4 m 1 m

Layer-3 CL 3~8 4~10 m 6m

Groundwater was encountered at 2.5 m depth in the 1stweek of May 2015

Near Dher wah lower, change=6 +825

BH.no Layer

Encounter

Type of

soil

SPT-N

value

Layer

Up to

Total

thickness

4

Layer-1 CL 3 0~4.0 m 4 m

Layer-2 ML 4~5 4~6 m 2 m

Layer-3 CL 5~8 6~10 m 4 m


Near narli wah Canal change=1 +080

Near Mari Mani Fold Change =0+100

BH.no Layer

Encounter

Type of

soil

SPT-N

value

Layer

Up to

Total

thickness

5,6Layer-1 ML 3~4 0~3.0 m 3 mLayer-2 CL 3~5 3~5 m 2 m

Layer-3 SP-SM 6~14 5~10 m 5 m



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6. GEOTECHNICAL PARAMETERS

The geotechnical parameters refer to the parameters related tocharacteristics of the subsurface materials for design and construction of

foundation and execution of earthwork. These parameters have been

developed on the basis of evaluation of the engineering characteristics of

the subsurface strata as determined through drilling records, field

exploration, in-situ testing (SPTs) and laboratory testing of the

representative samples of materials obtained from the boreholes. The

selection of parameters is discussed as follows:

6.1 UNIT WEIGHT

The unit weight of the subsurface material was estimated through

inspection and laboratory classification of the samples retrieved from

boreholes and through correlation with the SPT data. Typically, for the

purpose of calculations the bulk unit weight (bulk) of the representative soil

materials has been considered as 1.585 ~1.647 g/cm3. Following relation

should be used for submerged conditions.

(Sub= bulk- w) sub = Buoyant Unit Weight

w = Unit Weight of Water

In view of the fact that the site might be flooded or due to effects of future

rise in the groundwater table use of buoyant unit weight is recommended

for design purposes.

6.2 SHEAR STRENGTH PARAMETERS

The angle of internal friction applicable to the sub-soil layers encountered

at site has been estimated on the basis of N-values determined through

performance of SPTs at different locations in the area and at different

horizons within the layer. Most of the N-values determined in the subsoil


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fall in the range of to 22 blows/12 Inch. Corresponding to these values, a

value of 29.2 to 32.3 degrees is considered applicable to the sub-strata.

Conservative value of = 24 degrees has been adopted for calculation

purposes.

In case of select fill, the angle of internal friction should be taken as 32

degrees.

6.3 MODULUS OF ELASTICITY (Es)

The immediate settlement of foundation depends upon the elastic

properties of the load bearing strata, characterised by Modulus of Elasticity

(Es). The Modulus of Elasticity of soils is directly proportional to N-values

recorded in SPTs. The constant of proportionality depends upon the type of

soils in which the tests are carried out. For the strata, encountered in this

particular investigation, following relationship between Es and N-values

was used for calculation of immediate settlement:

Es= 500 (N + 15), kPa SAND layer

Es= (500 ~ 1,000), Su Clay layer

The above expression can also be used for select fill and N should be taken

as 15 in case select fill.

6.4 SELECTION OF FOUNDATION TYPE

Considering the anticipated structural loads and the load carrying

characteristics of the sub-soil strata at the site, Spread Footing/Mat footing

is considered technically feasible for the proposed Structures.

6.5 DEPTH OF FOUNDATION

All foundations must be laid at a safe depth that is free from the influence of

seasonal, climatic and environmental changes. Such safe depth must ensure

foundation safety and stability form the effects of wind erosion and erosion


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from surface run off. At the same time all foundations must be placed on

firm natural soil after removing any loose or undesirable soil. The

recommended minimum foundation depth for Spread footing/Mat footing

for the proposed structure is 3~5 feet measured from the existing ground

level.

Any loose and undesirable soil layer, if encountered during the excavation

for the foundations shall be replaced with structural backfill, rock fill or

lean concrete.

6.6 ALLOWABLE BEARING PRESSURES

The allowable bearing pressure for the design of foundations must not

exceed the allowable bearing capacity of the load carrying soil with respect

to shear failure. At the same time the settlement corresponding to the

allowable bearing pressure must not exceed the maximum allowable limit

of settlement for the particular foundation / structure system. In the

present case it is the allowable settlement criteria and not the shear failure

which will determine the allowable bearing pressure for design of

foundations.


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Allowable Bearing Capacity (qall) for Spread Footings(Near Railway Track Change=14 +275)

Depth ofFoundation (ft)

Width ofFoundation (ft)

SBC(ton/ft)

Settlement(mm)

2.5 4.0 0.53 13.52.5 5.0 0.61 23.02.5 6.0 0.75 25.134

Qult = cNc Sc + y DfNqSq+0.5yBNySyQall = Qult/FOS

Note:1. The calculations, presented above, are based on Terzaghis Bearing Capacity

equation.

2. The value of Ng ,Nq ,Nc in the formula was taken by (Vesic)

3. The value of Ng ,Nq ,Nc in the formula was taken by (Vesic)

4. Factor of Safety of 3 has been considered for the calculations above.

5. Settlement analysis have been made using Braja M. Das, (Principles of

Geotechnical Engineering, 5th

edition, 2002)

Recommendations

A. The tolerance of structures to settlement is function of type and size of

foundations.

The allowable total settlement for such structures as reported in the literature

Terzaghis Criteria of 25mm,which is considered maximum limit of the settlement

tolerable for spread/isolated footing.

B. Based on the project subsurface soil condition and bearing capacity analysisperformed, the recommended Allowable bearing capacity is restricted up to0.51 ton/ft based on the allowable settlement criteria.

C.Note

The Road Base layer should be of 0.25 m thickness each and compacted by avibrator system to achieve 95 % Modified proctor.

The degree of Compaction should be confirmed by In-situ Density tests.

Ground at foundation level should be properly compacted prior to laying of

structural fill.


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Allowable Bearing Capacity (qall) for Spread Footings

(Near Masu Wah canal Change=13 +650)



SBC(ton/ft)

Settlement(mm)

4.5 4.0 0.51 17.54.5 5.0 0.61 25.04.5 6.0 0.75 27.11


Note:

6. The calculations, presented above, are based on Terzaghis Bearing Capacity

equation.

7. The value of Ng ,Nq ,Nc in the formula was taken by (Vesic)8. The value of Ng ,Nq ,Nc in the formula was taken by (Vesic)

9. Factor of Safety of 3 has been considered for the calculations above.

10.Settlement analysis have been made using Braja M. Das, (Principles of


edition, 2002)

Recommendations

B. The tolerance of structures to settlement is function of type and size of

foundations.


Terzaghis Criteria of 25mm, which is considered maximum limit ofthe settlement



C.Note

The Road Base layer should be of 0.25 m thickness each and compacted by a

vibrator system to achieve 95 % Modified proctor.

The degree of Compaction should be confirmed by In-situ Density tests. Ground at foundation level should be properly compacted prior to laying of

structural fill.


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(Near Canal road crossing Kandyaro Change=10 +775)



SBC(ton/ft)

ImmediateSettlement

(mm)4 4.0 0.73 11.54 5.0 0.85 17.04 6.0 1.05 26.13


Note:

11.The calculations, presented above, are based on Terzaghis Bearing Capacity

equation.12.The value of Ng ,Nq ,Nc in the formula was taken by (Vesic)

13.The value of Ng ,Nq ,Nc in the formula was taken by (Vesic)

14.Factor of Safety of 3 has been considered for the calculations above.



edition, 2002)

Recommendations

C. The tolerance of structures to settlement is function of type and size of

foundations.


Terzaghis Criteria of 25mm, which is considered maximum limit of the settlementtolerable for spread/isolated footing.


C.Note





structural fill.


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(Near Dher Wah Lower, Change=6 +825)



SBC(ton/ft)

Settlement(mm)

5.0 4.0 0.63 18.55.0 5.0 0.71 24.19665.0 6.0 0.85 29.4


Note:


equation.17.The value of Ng ,Nq ,Nc in the formula was taken by (Vesic)





edition, 2002)

Recommendations

D. The tolerance of structures to settlement is function of type and size of

foundations.


Terzaghis Criteria of 25mm, which is considered maximum limit of the settlementtolerable for spread/isolated footing.


C.Note


vibrator system to achieve 95 % Modified proctor. The degree of Compaction should be confirmed by In-situ Density tests.


structural fill.


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(Near Narli Wah Canal Change=1 +080

Near Mari Mani Fold ,Change 0+100)



SBC(ton/ft)

ImmediateSettlement

(mm)3 4.0 0.73 11.53 5.0 0.81 17.03 6.0 0.95 26.


Note:


equation.






edition, 2002)

Recommendations

E. The tolerance of structures to settlement is function of type and size of

foundations.

The allowable total settlement for such structures as reported in the literatureTerzaghis Criteria of 25mm, which is considered maximum limit of the settlement



C.Note





structural fill

For & on Behalf of Geo Drillers Engineering


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IN-Situ Testing on Proposed Site for Natural gas Pipeline

Geo Tech Natural Gas

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