FINAL REPORT ON SOIL INVESTIGATION

Transcription

1 FINAL REPORT ON SOIL INVESTIGATION FOR PROPOSED CONSTRUCTION AT SS-6B AREA AT HPCL VISAKH REFINERY VISAKHAPATNAM ANDHRA PRADESH J.J. ASSOCIATES(VISAKHAPATNAM) AETP(P) LIMITED #11-6-3, RockDale Layout, MaharaniPeta, Visakhapatnam

2 Table of Contents Tables and Figures (Enclosures)... 1 INTRODUCTION SCOPE OF WORK INVESTIGATION METHODOLOGY FIELD INVESTIGATIONS Standard Penetration Tests Sampling LABORATORY INVESTIGATIONS Generalised geological profile Geological Profile for Proposed Construction of SS-6B area DESIGN SOIL PARAMETERS FOR FOUNDATIONS SUMMARY,ANALYSIS, CONCLUSIONS & RECOMMENDATIONS Tables and Figures (Enclosures) Field Bore logs Laboratory test results Bore Log Details Site Plan

3 1. INTRODUCTION M/s Hindustan Petroleum Corporation Limited proposed to conduct Soil Investigation at SS-6B Area in DHT project at Visakha Refinery,Visakhapatnam. Accordingly, land soil investigations were envisaged to evolve various soil/rock parameters in order to carry out engineering analysis and foundation design. In this connection, the soil investigation work was awarded to M/s J.J.Associates (VSKP) AETP Pvt Ltd., Visakhapatnam vide Purchase order No OQ dated 11/2/2010 to carry out the land soil investigations at the proposed site. Broad objectives of the investigations are as follows. (a) To evaluate the parameters of soil/rock at the proposed site. (b) To assess the engineering parameters and to estimate the safe bearing capacity of soil 2. SCOPE OF WORK The scope of work includes drilling of One(1) Land Boreholes at SS-6B Area. Location of the boreholes is presented in the enclosed figure. Borehole Locations sketch provided by M/S TOYO ENGINEERING CORPORATION / HPCL. The scope also includes carrying out field tests like Standard Penetration Test (SPT) in boreholes, collection of disturbed and undisturbed soil samples and carrying out the relevant laboratory tests on collected soil samples. 3. INVESTIGATION METHODOLOGY The details of the drilling rigs and methodology of boring are explained in the following sections. Boreholes were terminated as per the direction of Engineer In charge. After positioning the rig at the specified location, for drilling through soil. Borehole was sunk by mechanically operated Cable Tool (Shell & Auger) in soil and Rotary drilling in rock. Flush jointed steel casing tubes were provided to prevent possibility of side collapse in boreholes. After reaching the desired depth, depending upon the soil layer encountered, either Standard Penetration Tests & Vane Shear Tests were conducted or Undisturbed or disturbed soil samples were collected. 1 J.J.ASSOCIATES (Vskp) AETP (P) LIMITED

4 The location of the boreholes is shown in the enclosed sketch. The field tests and sample collections were conducted in the boreholes in accordance with the relevant Indian Standard codes of practice and as per the following. (a) (b) Standard Penetration Test in soils at regular depth intervals Disturbed & Undisturbed soil samples 4. FIELD INVESTIGATIONS 4.1 Standard Penetration Tests Standard penetration tests (SPT) were carried out in soil within boreholes to determine strength characteristics of soil. This was carried out in accordance with IS: The number of blows required to drive the standard split spoon sampler for penetration of 0.30 m by a 63.5 kg hammer falling freely from a height of 750 mm is recorded N Value at regular intervals in the borehole. If the sampler is not fully penetrating into soil, then the test was terminated after refusal noting the rate of penetration. 4.2 Sampling Disturbed & Undisturbed representative soil samples were collected during investigations and subsequently sent to laboratory for visual examination and testing. The disturbed soil samples were also collected from split spoon sampler. 5. LABORATORY INVESTIGATIONS All collected soil samples from the boreholes were brought to laboratory for necessary testing and rechecking the preliminary borelogs. The laboratory tests comprised of a. Grain Size distribution of all samples collected from boreholes Grain size distribution was determined in two stages. The soil fraction retained on 75 micron IS Sieve was analysed by Sieve analysis using standard set of IS Sieve as prescribed by IS Sieve analysis is again done in two stages. The oven dried samples of soil was separated into two fractions by passing it through 4.75mm IS Sieve. The portion passing through the sieve was analysed by fine analysis using the IS Sieve Nos. 2mm, 1mm, 500, 425, 300, 212, 150 and 75 microns. The portion retained on this sieve was analysed by coarse analysis using IS Sieve Nos. 100, 60, 20, 10 and 4.75mm. 2 J.J.ASSOCIATES (Vskp) AETP (P) LIMITED

5 b. Atterberg Limits on all clay fractions Liquid limit of the soil was determined by Casagrande method using Casagrande type mechanical liquid limit apparatus. Plastic limit was determined as per the standard procedure. c. Natural moisture content Natural moisture content of the soil was determined by oven drying method as per IS : 2720 Part II, Weights were taken to an accuracy of 0.001gr. d. Bulk & Dry density Bulk density and dry density of the undisturbed soil samples were evaluated as per IS:2720 e. Triaxial Test. The encountered strata was stiff in consistency, careful attention is made to extract sample from the tube. The test is conducted as per part of IS f. Specific Gravity Tests Specific gravity test was conducted on the soil fraction passing through 425 micron I.S.Sieve by density bottle method or by pycnometer. All weights are taken to an accuracy of gr. and the tests were conducted at 27 C. g. Chemical Analysis of soil & water Chemical Analysis for soil and water were carried out for PH value chlorides, sulphates and organic matter and the results are enclosed in the report. h. Consolidation tests Consolidation tests were conducted on vertical drainage using Fixed ring cell type consolidometer. The soil specimens were allowed to consolidate under pressure increments of 0.01, 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 kg/cmª. The pressures were unloaded through increments of 4.00, 2.00, 1.00, 0.50, 0.25 and 0.01 kg/cmª. Each pressure increment was maintained constant per 24 hours. The vertical compression was measured after the application of each pressure increment after the following elapsed times, 0, 0.25, 1.00, 2.25, 4.00, 6.25, 9.20, 12, 25, 16.00, 20.25, 25, 36, 49, 64, 81, 100, 225, 400, 720 and 1440 minutes. Note : The Possible tests are only conducted if samples were collected. In some case soil samples could not be collected as rock is met at shallow depth. 3 J.J.ASSOCIATES (Vskp) AETP (P) LIMITED

6 6.GENERALISED GEOLOGICAL PROFILE A generalised geological profile is prepared for individual boreholes. The description of the various layers is based on the laboratory test results based on IS classification. For the purpose of clarity, existing ground level is considered as 0.0m, datum for boreholes in the individual geological profile. 6.1 Geological profile of proposed SS-6B Area(Bh-7). Bore logs at proposed SS-6B Area shows the soil strata as per Field observation & bore log. The geology of the proposed site is varying with respect to the thickness of each layer. The top over burden predominantly consists of Filled up material from 0.00 to 1.00m followed by Clay with Sand, Highly Weathered rock. The ground water Level is observed in the bore hole at shallow depth. Soil Properties 0.00 to 1.00m 1.00m to 2.50m 2.50m & below Gravel content % Filled up 7 to 11 Sand content % material 31 to 43 Silt and Clay content % 46 to 62 Soil Classification as per IS CL-SC Note : A layer of Clay with pebbles observed from 6.00m to 6.50m 7.Suggested Design Soil Parameters Layer No. Depth Below GL FROM TO Soil type Filled up material Average N-Value Highly rock Cu t/m 2 Ф degree Weathered γ t/m Clay with sand & pebbles m & below Highly weathered rock 8. SUMMARY, ANALYSIS, CONCLUSIONS & RECOMMENDATIONS 8.1 General The summary of the investigation is given below. Total One (1) borehole is conducted in the proposed site. 4 J.J.ASSOCIATES (Vskp) AETP (P) LIMITED

7 8.2 Analysis SAFE BERING CAPACITY FROM SHEAR CRITERIA IN BOREHOLE 7 Safe Bearing Capacity from shear criteria at a depth of 2.50m Q ns = (2/3 CN C S C D C I C + r D f (N Q -1) S Q D Q I Q + 0.5r BN r S r D r I r W r ) / FS C = Cohesion intercept = 0 kg/cm 2 ø = 36 ø = IF(ø <=28,(TAN -¹ (0.67*TAN ø )Else ø) N C N Q N r = Bearing capacity factors which are obtained by interpolation Here N C = N Q = N r = S C S Q S r = Shape factors which are 1.00 for Strip and 1.30 for Square I C I Q I r = Inclination factors Nø = tan 2 (((22/7)/4) + (ø/2) ) D C = 1 + ( 0.2 x (Depth / Width) x Nø) here it is D Q = D r = 1 for ø > 10 D Q = D r = 1 + ( 0.1 x (Depth/Breadth) x Nø) for ø > 10 Here D r = D Q = Qns = Safe Bearing Capacity Factor of safety : 3.00 Safe Bearing Capacity from shear criteria at a depth of 2.50m S No. Depth Width Length Net safe Bearing Capacity in t/m 2 Strip Square Taking N = 50, SBC Calculation as per IS:8009 (Part-I)-1976 from Settlement Criteria at a depth of 2.50m below G.L(i:e) at R.L in Bore Hole-7. 5 J.J.ASSOCIATES (Vskp) AETP (P) LIMITED

8 S No. Depth of Width of Settlement Allowable bearing Foundation Foundation Pressure for pressure for 25mm 10t/m 2 settlement(t/m 2 ) Recommendations: Considering the subsoil conditions prevailing at the site and based on field and laboratory investigation results, the following recommendations have been made for foundations of proposed constructions. 1. Shallow Foundations a) As Hard strata is met at shallow depth and taking both shear criteria & settlement criteria into consideration raft foundation/ isolated column footings should be adopted at the depths mentioned below with the following safe bearing capacities. BH No. Location Depth of foundation SBC from shear criteria (t/m 2 ) 7 SS-6B Area 2.50m & below 30 Note: 1. Filled up material if any should be removed and foundation should be from the natural ground level 2. Plinth beams are to be provided to safeguard the structure against differential settlements if any. b ) Due to presence of sulphates in water necessary precautions should be taken as per IS c) Back Filling material should be Rubble Soling and well compacted in layers of 150mm below PCC. For J.J.ASSOCIATES(VSKP) AETP (P) LTD., 6 J.J.ASSOCIATES (Vskp) AETP (P) LIMITED

9 J.J. ASSOCIATES(VISAKHAPATNAM)AETP(P) LIMITED ,RockDale Layout, Maharanipeta, Visakhapatnam Project : Proposed DHT project at Visakh Refinery. Date of Commencement : 1/4/2010 Location : SS-6B Date of completion : 6/4/2010 Bore hole : 7 Ground RL : Ground Water Table : 1.93m Coordinates : N E BORELOG Ground R.L. Depth Below G.L. From To From To Visual Description of strata Filled up soil & boulders Reddish clay with pebbles Highly weathered rock Reddish clay with pebbles Thickness of Strata Type of sample RL & Depth at which sample collected GL GRL 1.00 DS SPT-1 DS SPT-2 DS-3 SPT-3 DS DS RL & Depth at which SPT conducted GRL GL 15 cm SPT 30 cm 45 cm N- Value (5 cm pen.) 58(5cm pen.) >50 >50 Core recovery % RQD % Remarks UDS Undisturbed Sample DS Disturbed Sample SPT Standard Penetration Test pen. Penetration 1

10 J.J. ASSOCIATES(VISAKHAPATNAM)AETP(P) LIMITED ,RockDale Layout, Maharanipeta, Visakhapatnam Project : Proposed DHT project at Visakh Refinery. Date of Commencement : 1/4/2010 Location : SS-6B Date of completion : 6/4/2010 Bore hole : 7 Ground RL : Ground Water Table : 1.93m Coordinates : N E Ground R.L. Depth Below G.L. From To From To Visual Description of strata Thickness of Strata Type of sample RL & Depth at which sample collected GL GRL RL & Depth at which SPT SPT N- conducted Value GL GRL cm cm cm (10cm pen.) >53 Core recovery % SPT DS Nil Nil DS Nil Nil SPT (5cm pen.) >50 Highly Nil Nil DS weathered DS Nil rock SPT (10cm pen.) >73 2 Nil DS Nil Nil SPT (8cm pen.) >81 Nil Nil SPT (no pen.) >100 Nil Nil RQD % Remarks Borehole terminated at 15.35m below G.L. (i.e.) at R.L UDS Undisturbed Sample DS Disturbed Sample SPT Standard Penetration Test pen. Penetration 2

11 J.J. ASSOCIATES(VISAKHAPATNAM) AETP(P) LIMITED #11-6-3, RockDale Layout, MaharaniPeta, Visakhapatnam IDENTIFICATION & ENGINEERING PROPERTIES OF SOIL Project : Proposed DHT project at HPCL, Visakh Refinery at Visakhapatnam Location : Proposed SS-6B Site. Sl No. BH No Sample No Type of sample RL & Depth at which sample collected GRL GL SPT DS Natural moisture content (%) Bulk Density (g/cc) Dry Density (g/cc) Gravel (%) Gradation Analysis FINES Sand (%) Silt Clay Liquid Limit (%) Consistency Limits Plastic Limit (%) Plastici ty Index (%) Triaxial Test UU C (kg/cm²) φ degree Specific gravity CL SC DS NP ISC -

12 J.J. ASSOCIATES (VISAKHAPATNAM) (P) LIMITED #11-6-3, Rock Dale Layout, Maharanipeta, Visakhapatnam Project Location : Proposed DHT Project at Visakh Refinery. : SS-6B Area. CHEMICAL ANALYSIS OF SOIL Depth at which Organic BH sample collected Sulphates Chlorides S.No. Pн Matter No. G.L % % G.R.L. % nil CHEMICAL ANALYSIS OF WATER Depth at which Organic BH sample collected Sulphates Chlorides S.No. Pн Matter No. G.L mg/l mg/l G.R.L. mg/l

13 J.J. ASSOCIATES(VISAKHAPATNAM) AETP (P) LIMITED #11-6-3, Rock Dale Layout, Maharanipeta, Visakhapatnam BORE LOG DETAILS Project Location : Proposed DHT Project at Visakh Refinery. : At Proposed SS-6B Site. BH Filled up soil & boulders Reddish clay N=13@ with pebbles Highly weathered rock Reddish clay with pebbles Highly weathered rock N>50@ N>50@ N>53@ N>50@ N>73@ N>81@ N>100@