Prepared By M/s SOHAMS FOUNDATION ENGG. PVT. LTD. 301, Thaper Complex, Sector-15, CBD Belapur, Navi Mumbai Tel: , Fax:

Transcription

1 CLIENT: M/S HINDUSTAN PETROLEUM CORPORATION LTD (HPCL) FINAL REPORT ON GEOTECHNICAL INVESTIGATION FOR DIESEL HYDRO TREATER PROJECT AT VISAKHA REFINARY (HDHT), VIZAG - Control Room Prepared By M/s SOHAMS FOUNDATION ENGG. PVT. LTD. 301, Thaper Complex, Sector-15, CBD Belapur, Navi Mumbai Tel: , Fax: sohamsfoundation@vsnl.net Website: JOB NO.: 0827 SEPTEMBER 2009

2 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai REPORT ON GEOTECHNICAL INVESTIGATION FOR DIESEL HYDRO TREATER PROJECT AT VISAKH REFINERY (HDHT), VIZAG CONTROL ROOM 1.0 Preamble Hindustan Petroleum Corporation Ltd. (HPCL) has planned to develop the Diesel Hydro Treater (DHT) at Visakh Refinery. It is necessary to carry out the soil investigation to design the suitable type of foundation. The work of Geotechnical investigation was awarded to M/s Sohams Foundation Engineering Pvt. Ltd. (SFEPL), Mumbai. 301/02/03, Thaper Complex, Plot No 51, Sector-15, CBD Belapur, Navi Mumbai Scope of Work 2.1 The objectives of investigation were to obtain: A) Subsurface profile detailing different stratum and their variation along the alignment. B) To determine the engineering properties of the stratum and design parameters to decide the suitable foundation. 2.2 To study the properties of the strata, it was decided to take two boreholes. The locations of the boreholes are shown in the location plan (Annexure I). 2.3 Two boreholes were drilled during the period of 5 th February 2009 to 9 th February. The diameter of the boreholes was 100 mm in soil or top of rock whichever occurs earlier, as per specification and instruction of Engineer-in -charge. The sides of the boreholes were supported by temporary casing. Drilling was carried out in rock stratum using Nx size diamond Bit and Double Tube core barrel. All work was executed as per IS The borehole logs, detailing the reference number of borehole, the description of the material with depth, the results of in-situ testing, and the depth of boreholes are presented in boring logs Annexure II. 2.4 The undisturbed soil (UDS) samples were collected at 3.0 m interval in the clayey soil. Undisturbed soil samples were collected using thin walled tube samplers. The ends of the sampler were immediately packed using a thin layer of wax to avoid further disturbance of samples, loss of moisture etc. Report By: Kumar Job No-827 Checked By: SPB Page 1

3 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai The identification marks such as project, location; borehole number and depth were marked / painted immediately on the sampler. 2.5 In-situ field-test such as Standard Penetration Tests were conducted in each boreholes at a vertical interval of 3.0 m. The tests were conducted as per IS The test is basically a penetration test in which, a thick wall split tube sampler, is driven into the undisturbed soil at the bottom of the hole under the blows of a 63.5 kg drive weight with 75 cm free fall. The sampler is first driven through 15 cm as a seating drive. It is further driven through 30 cm or until 50 blows have been applied. The number of blows required to drive the sampler 30 cm beyond the seating drive is termed as Penetration Resistance N. The samples collected were preserved in polythene bags and were used as disturbed samples for laboratory testing. The tag of identification marks such as project, location, borehole number, sample number, penetration resistance with blows for each 15 cms and depth were attached to the sample. 2.6 In-situ field test such as Vane shear Test (VST) are conducted in the boreholes when the soil has very low shear strength or SPT penetration resistance N is less than or equal to 1. In-Situ Vane Shear Test for soils was conducted as per IS In this test when the borehole was drilled till the test depth the vane of 50 mm size was attached to the rods and lowered in the borehole to the test depth. The vane was pushed with a moderate steady force up to a depth of five times the diameter of the borehole. Then the torque applicator was fixed to the anchor plate and rods were connected to it. The vane was rotated at the rate 0.1 deg/sec with the help of gear handle. The maximum torque reading was noted. 2.7 The Dynamic cone penetration test (DCPT) was carried out as per IS 4968 (Part-I). The test is basically to determine resistance of different soil strata to dynamic penetration of a 50 mm cone. In this test 50 mm diameter cone 60 fitted loosely to the driving rod through a cone adopter. The cone is driven into the undisturbed soil at the bottom of the hole under the blows of a 63.5 kg drive weight with 75 cm free fall. The number of blows for every 10 cm penetration of the cone is recorded. The process is repeated till the cone is driven to the required depth or till the refusal. Report By: Kumar Job No-827 Checked By: SPB Page 2

4 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai Field California Rearing Ratio (CBR) Test was carried out at the locations indicated by engineer-in-charge to determine the strength of sub-grade and bases of roads. The test basically a penetration test. The load is applied using a loading jack and truck or tractor shall be used to give the necessary reaction. The surcharge annular weight of kg shall be placed at the location of test indicated by engineerin-charge. Load shall be applied so that the penetration is approximately 1.25 mm/min. The load readings shall be taken at penetration of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 10.0, 12.5 mm. The maximum load and penetration shall be recorded if it occurs for a penetration less than 12.5 mm. 2.9 Disturbed split spoon samples were obtained from the boreholes. Disturbed samples using a split barrel tube sampler were obtained at every depth where SPT was performed in the soil formation Depth of Ground water table was recorded in each borehole after 24 hrs and water samples were collected for chemical analysis Selected Disturbed Soil Samples were tested in SFE Lab for the following tests: Natural Moisture Content (NMC) Specific Gravity Grain Size Analysis Atterbergs Limits Free Swell Index Chemical Analysis (ph, Sulphates and Chlorides) The Undisturbed soil sample was tested for the following tests in addition to these tests. Bulk Density Unconsolidated Undrained Triaxial Test Unconfined Compressive Strength (UCS) Test Consolidation Test 2.12 Water Samples were tested for the following tests: ph Sulphates Chlorides Report By: Kumar Job No-827 Checked By: SPB Page 3

5 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai The field and laboratory work was executed generally in accordance with the I.S. specifications listed below. IS : Classification and identification of soils for general engineering purpose. IS 2131: Method for standard penetration test for soils. IS 2132: Code of practice for thin walled tube sampling of soils. IS 2720 (I): Preparation of Dry Samples various Tests. IS 2720 (II): Determination of Water Content. IS 2720 (III): Determination of specific gravity of soil IS 2720 (IV): Grain Size Analysis IS 2720 (V): Determination of Liquid and Plastic Limit. IS (XI): Determination of shear strength parameter of soil Unconsolidated Untrained triaxial compression test without measurement of pore pressure. IS (XL): Free swell Index Test IS 4464: Code of practice for information and core description in foundation investigation. IS 2911 (II/2): Code of practice for design and construction of bored cast- insitu concrete piles. IS Code of practice for design and construction of Shallow Foundation on Rock. IS Code of practice for design and construction of bored cast- in situ piles foundation on rocks - Guidelines 2.14 The fieldwork carried out is summarized as follows: Report By: Kumar Job No-827 Checked By: SPB Page 4

6 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai Sr. No. Table 1: Summary of fieldwork BH. No. Co-ordinate RL Depth of Water table Northing Easting below existing GL (m) Depth of Borehole below existing GL (m) 1 BH BH CBR DCPT ERT Findings of Investigation Based on the data of these three boreholes, the sub-surface in this area was observed as 1. Filling Material with Gravels and Boulders 2. Brownish to Grayish Silty/Sandy Clay 3. Light Brownish/Grayish colored Highly Weathered Rock The ground water table was observed at a depth of m below the existing ground level. However the same may rise above during the monsoons. The top layer observed was filled up material, with gravels and boulders having thickness of 1.5 m. The second layer identified was Brownish to Grayish Silty/Sandy Clay up to the depth of 9.0 m. The Standard Penetration Tests, Vane shear Test were conducted in this stratum and N-values found in the range from 4 to 19. The laboratory tests conducted on selected disturbed soil samples and undisturbed soil samples indicated the following range of values (Ref. Annexure III) Natural Moisture content : (%) Specific Gravity : Bulk Density : (g/cc) Gravel : 0 (%) Sand : (%) Silt + Clay : (%) Report By: Kumar Job No-827 Checked By: SPB Page 5

7 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai Liquid Limit : (%) Plastic Limit : 30 (%) Free Swell Index : 10 (%) Triaxial Shear properties : Cohesion (Cuu) : 0.07 (kg/cm²) Angle of Friction, uu : 22 (deg) Unconfined Compressive Strength(qu) : 0.12 (kg/cm²) Shear Strength from VST : (kg/cm²) The final layer observed in the borehole was Light Brownish/Grayish colored Highly Weathered Rock. The core recovery in this stratum was Nil whereas RQD is Nil. 4.0 General Discussions for the Choice of Suitable Foundation Based on the field observations and laboratory test results the founding levels and the allowable bearing capacity which can be considered at that level shall be determined by considering the basic criteria as The foundation should carry the maximum loads coming from the structure with margin of factor of safety, and, The probable maximum and differential settlement of the soil under any part of the foundation must be limited to safe and tolerable limits. 5.0 Conclusions and Recommendations According to the field and laboratory investigation, subsurface conditions, engineering analysis and practical experience, it can be concluded that proposed structures/ facilities can be satisfactorily supported by the ground at site, provided that the following suggestions are taken into considerations: Shallow Foundation on Engineered Fill It has been found that the upper stratum is filled up Material with Gravels and Boulders. This stratum is existed up to 1.50 m BEGL. The layer of Brownish to Grayish Silty/Sandy Clay layer is the followed by upper filling material. The layer varies from 1.5 m to 9.0 m BEGL. Based on the SPT value and laboratory test results the safe bearing capacity of this is evaluated as 4.0 t/m 2. The type of soil mainly constituting for foundation as per Table-1 of IS1893 (Part1):2002 is Type III-Soft soils. Report By: Kumar Job No-827 Checked By: SPB Page 6

8 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai The minimum depth of foundation shall be 1.0 m BEGL. The compound wall foundation, light weight structures, security cabin foundation, road construction could be rested in this filled up soil or underlain clay soil, with treated below A. Excavate the existing ground surface to a depth of 1.0 m below the foundation level and laterally to a minimum of 1.0 m from the edge of the foundation. B. Excavation work will be above water table, so dewatering would not be required. However, incase dewatering is necessary, dewatering level shall be minimum 0.5 m below excavation level to achieve proper compaction. C. The exposed sub grade at 2.0 m depth should be proof rolled by heavy vibratory roller (roller with 10 to 20 tons roller usually used in roads construction). Any soft, organic or any other unsuitable material exposed shall be removed and replaced with well compacted granular material. D. Granular materials shall be laid in the layers of 250 mm thick to maximum dry density of 95 %. E. A biaxial/uniaxial Geodrid can be use below the footing for uniform distribution of structural load on soil. Shallow foundation on improved soil by Stone column The light to medium loaded structures, area loading structures, tank foundation, roads etc. required the SBC more than 10 t/m 2 to 15 t/m 2, it is suggested to treat the soft ground by using stone column. The treatment by using stone column improves the bearing capacity of foundation soil and also reduces post construction settlement of foundation and also reduces settlement potential of soft layer below the heavily loaded roads. Vibroreplacement method is used to create a stone column of 750 mm to 900 mm diameter up to 11.0 m below the existing ground level by sinking the vibratory device, backfilling the induced hole by adding stones commonly ranges in gradation from 25 mm to 75 mm. The spacing of stone column shall be decided from the structural requirement. Road Construction The upper filling layer shall be considered as sub grade for road construction. Report By: Kumar Job No-827 Checked By: SPB Page 7

9 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai The CBR test was conducted on existing filled up material and the average CBR value is %. Excavation In case of deep excavation more than 4 m it is advisable to design the deep excavation system. A. The touch pile system. B. A sheet pile wall for lateral support. C. Diaphragm wall system. Pile Foundation on Rock (For Heavy Structures) The study of the field tests and laboratory tests clearly indicate that a soft soil is present up to a depth of 9.0 m below the existing ground level. The soil can be described as Highly Compressible Soft Sandy/ Silty Clay based on the laboratory test results. Such soils can not bear the loads of high magnitudes and also undergoes a large amount of settlements even under the application of very small load. Moreover the foundation has to sustain heavy loads from the structure. Hence the boredcast-in-situ piles shall be provided at this location to transfer the load of structure to the rock. The pile can be designed for end bearing. Socket lengths of three times diameter shall be provided for piles. Based on the laboratory test results theoretically the capacity of the bored cast-in-situ pile is tabulated in the following page. The values in Table 5.1 are estimated for preliminary design. A detailed final design should be carried out by the structural engineer taking into consideration all possible loading conditions, which may be applied on piles. Table 5.1: Safe Bearing Capacity of piles Depth of Safe Vertical Lateral Net Uplift Diameter of pile Capacity of Capacity of capacity of piles BEGL pile piles piles (mm) (m) (Tons) (Tons) (Tons) The typical Calculations are appended as Annexure V. Report By: Kumar Job No-827 Checked By: SPB Page 8

10 Client: Hindustan Petroleum Corporation Ltd. Report Control Room SOHAMS FOUNDATION ENGG PVT LTD 301,Thaper Complex, Sector 15, CBD Belapur, Navi Mumbai Piles shall be embedded in the stratum identified as Light Brownish/Grayish colored Highly Weathered Rock The piles shall be socketed below the depth at which t he chiseling energy imparted to the rock shall not less than 100 T-m/sqm/cm penetrations. The piles shall be terminated at the level mentioned in the table or chiseling criteria whichever meets earlier. The load carrying capacity shall be verified by conducting Initial. Lateral and uplift Pile load tests. The type of soil mainly constituting for deep foundation as per Table-1 of IS1893 (Part1):2002 is Type I-Rock or hard soil. 6.0 Chemical Analysis The Chemical analysis of the soil samples indicate the ph values ranging from 8.0 to The Chloride content of the soil is varying from 0.16 % to 0.18 % and Sulphate as SO 3 - is varying from % to %. As per IS 456, as the sulphate is less than 0.20 % Ordinary Portland Cement or Rapid Hardening Portland Cement or combination of the same can be used for concrete. Minimum Cement content shall be 310 kg/m 3 for concreting and the maximum water cement ratio shall be 0.55 for concreting. The Chemical analysis of water sample indicate the following range of values ph : Chloride : ppm Sulphate : ppm Report By: Kumar Job No-827 Checked By: SPB Page 9

11 ANNEXURE I LOCATION PLAN

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13 ANNEXURE II BORELOGS

14 ANNEXURE III LABORATORY TEST RESULTS

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17 Project: Geotechnical Investigations for Diesel Hydro Treater Project SOHAMS FOUNDATION ENGG PVT LTD at Visakh Refinery 301-3,THAPAR COMPLEX,SECTOR 15,CBD BELAPUR, NAVI MUMBAI Client: M/s Hindustan Petroleum Corporation Limited,Mumbai TEL: / FAX: sohamsfoundation@vsnl.net website: Summary of Laboratory Test Results - Disturbed Samples Location BH No Sample Sample NMC Sp Gravel Sand Silt Clay LL PL PI FSI Details Depth(m) (%) Gravity (%) (%) (%) (%) (%) (%) (%) (%) Control Room BH 48 SPT Control Room BH 48 SPT NP - - Control Room BH 49 SPT Control Room BH 49 SPT N M C : Natural Moisture Content L L : Liquid Limit S L : Shrinkage limit γb: Bulk Density G S A : Grain Size Analysis P L : Plastic Limit FSI :Free Swell Index C: undrained cohesion NP : Non-Plastic P I : Plasticity Index Swp: Swelling Pressure φ : Angle of internal friction Tests as per IS 2720 Conducted By: H.D Checked By: KuMaR Job No 827 Soil Classification as per IS 1498 Prepared By: TARULATA Page No

18 Project: Geotechnical Investigations for Diesel Hydro Treater Project SOHAMS FOUNDATION ENGG PVT LTD at Visakh Refinery 301-3,THAPAR COMPLEX,SECTOR 15,CBD BELAPUR, NAVI MUMBAI Client: M/s Hindustan Petroleum Corporation Limited,Mumbai TEL: / FAX: sohamsfoundation@vsnl.net website: Summary of Laboratory Test Results - Undisturbed Samples Location BH No Sample Details Sample Depth NMC Sp Gravity Gravel Sand Silt Clay LL PL PI γb Triaxial Test(UU) Unconfined Compressive Strength (qu) Consolidation Test Cuu Фuu Cc eo Cv (m) (%) (%) (%) (%) (%) (%) (%) (%) (g/cc) (kg/cm²) (Deg) (kg/cm²) (m 2 /yr) Control Room BH-48 UDS Control Room BH-49 UDS N M C : Natural Moisture Content L L : Liquid Limit γb: Bulk Density Cc : Compression Index G S A : Grain Size Analysis P L : Plastic Limit C: undrained cohesion e0 : Initial Void Ratio NP : Non-Plastic P I : Plasticity Index φ : Angle of internal friction Cv:Coefficient of Consolidation Tuu : Unconsolidated Undrained TriaS L : Shrinkage limit pc : Preconsolidation Pressure Tests as per IS 2720 Conducted By: H.D Checked By: KuMaR Job No 827 Soil Classification as per IS 1498 Prepared By: TARULATA Page No

19 Project: Soil Investigation and Topographical Survey for DHT Project at Visakha Refinery, Visakhapatnam Client: Hindustan Petroleum Corporation Ltd. SFE Summery of Chemical Analysis of Soil and Water Location Sample Details Sample Depth, m p H Chloride Sulphate Sulphates as So3 with 2:1 Water soil extract Unit % % % Limit as per IS % 0.04% BH 48 Soil BH 49 Soil Unit PPM PPM Limit as per IS PPM 400 PPM BH 48 Water BH 49 Water

20 Project: Client: Soil Investigation and Topographical Survey for DHT Project at Visakha Refinery, Visakhapatnam Hindustan Petroleum Corporation Ltd. SFE Field Vane Shear Test Results BH No Depth Shear Strength Cohesion (m) BHGL kg/cm 2 kg/cm 2 BH BH

21 Sohams Foundation Engg Pvt Ltd Project: Geotechnical Investigation for Diesel Hydro 301, Thaper Complex, Sector 15, Navi Mumbai Treater Project at Visakha Refinery Tel: , Fax : Client :Hindustan Petroleum Corporation Limited,Mumbai Determination of N Value from Dynamic Cone Penetration Test (DCPT - 11) Sr. No. Depth of test, m BEGL Dynamic Cone Penetration Value N Values

22 Sohams Foundation Engg Pvt Ltd Project: Geotechnical Investigation for Diesel Hydro 301, Thaper Complex, Sector 15, Navi Mumbai Treater Project at Visakha Refinery Tel: , Fax : Client :Hindustan Petroleum Corporation Limited,Mumbai Dyanamic Cone Penetration Test (DCPT - 11) at Control Room 0.0 No of Blows Depth of Test BOGL (m)

23 Project : Client : Geotechnical Investigations for Diesel Hydro Treater Project at Visakh Refinery M/s Hindustan Petroleum Corporation Limited,Mumbai CALIFORNIA BEARING RATIO TEST ( CBR) SFE Location CBR Capacity of Proving Ring 5.00 Tons Test Date 14-Mar-09 Proving Ring Constant Test Depth 5 cm BEGL L.C. of Proving Ring mm Co-Ordinates E , N L.C. of Dial Gauge mm Condition of Test- soaked Moisture Content 34.0 % Surcharge Weight used 5.00 kg Penetration Actual Load Penetration Standard Load mm kg mm kg Bearing 2.50 mm penetration Load (k kg) Penetration (mm) Bearing 5.00 mm penetration CBR Value (%) Location CBR Capacity of Proving Ring 5.00 Tons Test Date 14-Mar-09 Proving Ring Constant 6.30 Test Depth 5 cm BEGL L.C. of Proving Ring mm Co-Ordinates E , N L.C. of Dial Gauge mm Condition of Test- soaked Moisture Content 34.0 % Surcharge Weight used 5.00 kg Penetration Actual Load Penetration Standard Load mm kg mm kg Bearing 2.50 mm penetration Bearing 5.00 mm penetration CBR Value (%) Load (kg) Penetration (mm)

24 Project : Client : Geotechnical Investigations for Diesel Hydro Treater Project at Visakh Refinery M/s Hindustan Petroleum Corporation Limited,Mumbai CALIFORNIA BEARING RATIO TEST ( CBR) Location CBR Capacity of Proving Ring 5.00 Tons Test Date 14-Mar-09 Proving Ring Constant 6.30 Test Depth 5 cm BEGL L.C. of Proving Ring mm Co-Ordinates E , N L.C. of Dial Gauge mm Condition of Test- Soaked Moisture Content 34.0 % Surcharge Weight used 5.00 kg Penetration Actual Standard Penetration Load Load 600 mm kg mm kg Bearing 2.50 mm penetration Lo oad (kg) SFE Penetration (mm) Bearing 5.00 mm penetration CBR Value (%)

25 ANNEXURE IV TYPICAL CALCULATIONS

26 Project: Client: Soil Investigation and Topographical Survey for DHT Project at Visakha Refinery, Visakhapatnam Hindustan Petroleum Corporation Ltd. SFE Determination of Bearing Capacity (Bearing Capacity Based on SPT "N" Resistance) BH No BH 49 Strata Identification Silty Clayey Sand Depth (From / To) 1.50 to 9.0 Thickness of stratum Ground water Table, (m) BGL 0.90 SPT Penetration "N" 8 Now, based on the SPT penetration the allowable safe bearing capacity for 25 mm settlement and with factor of safety 3 can be calculated as per Terzaghi & Peck as - q ap = 3.5 (N - 3) [(B+0.3) / 2B] 2 R w2 Rd (T/m 2 ) Where, q ap : Allowable safe bearing capacity based on SPT penetration "N" in T/m 2 N : Average Standard Penetration Resistance = 8 B : Width of Footing (or least lateral dimension) in (m) = 1.00 D : Depth of foundation below ground level in (m) = 2-6 R w2 : Correction for Water table = 0.5 [ 1 + (Z w2 / B) ] Z w2 : Depth of water table below foundation in (m) Rd : Correction for depth = (D/B) (maximum limited to 1.20) Now, N - 3 = 5 R w2 = 0.50 Rd = 1.20 [(B+0.3) / 2B] 2 = 0.42 Hence, q ap = 3.50 * 5 * 0.42 * 0.50 * 1.20 q ap = 4.44 consider q ap = 4 T/m 2 Hence, the allowable safe bearing capacity based on SPT penetration "N" can be considered as 4 T/sqm at a depth of 2-6 m below ground level

27 Project: Client: Soil Investigation and Topographical Survey for DHT Project at Visakha Refinery, Visakhapatnam Hindustan Petroleum Corporation Ltd. SFE Determination of Bearing Capacity - Shear Criteria (Bearing Capacity as per IS 6403) BH No BH 48 Strata Identification Silty/Sandy Clay Ground water Table, (m) BGL 1.00 Now, based on the IS 6403 equation for general shear failure the Ultimete net bearing capacity can be calculated as, q d = c N c s c d c i c + q(n q -1)s q d q i q + 1/2 Bγ N γ s γ d γ i γ W' (T/m 2 ) Where, q d : Ultimete net bearing capacity in T/m 2 q : Effective surcharge at the base level of foundation = γ D f = 4.0 c : Average Cohesion in T/m 2 = 0.24 N c : Bearing capacity factor = N q : Bearing capacity factor = 8.10 N γ : Bearing capacity factor = 7.59 s c : Shape Factor for square footing = 1.30 sq : Shape Factor for square footing = 1.20 sγ : Shape Factor for square footing = 0.80 d c : Depth Factor = D f /B(Nφ) 1/2 = 1.04 dq : Depth Factor = D f /B(Nφ) 1/2 for φ > 10 = 1.02 dγ : Depth Factor = D f /B(Nφ) 1/2 for φ > 10 = 1.02 i c : inclination factor = (1- α/90) 2 = 1.00 iq : inclination factor = (1- α/90) 2 = 1.00 iγ : inclination factor = (1- α/φ) 2 = 1.00 W' : Water Correction factor = 0.5 φ : Angle of Internal friction = 22 Nφ : tan 2 (π/4 + φ/2) = D f : Depth of Footing, m = 2.0 γ : Unit Weight of soil, T/m 2 = 2.0 B : Width of footing ( Assume), m = 2.0 α : Inclination of the load to the vertical in degree = 0 Hence, q d = T/m 2 Consider Factor of Safety = 3 Hence, the net safe bearing capacity based on IS 6403 equation can be considered as = 46.55/3 = T/m 2

28 Project: Client: Soil Investigation and Topographical Survey for DHT Project at Visakha Refinery, Visakhapatnam Hindustan Petroleum Corporation Ltd. SFE Determination of Load Carrying capacity of Pile (As per IS 14593) Based on the study of the field results, the strata can be described as Highly to Moderately Weathered Rock Hence, the safe load carrying capacity of pile shall be evaluated as per IS From the various methods available, the pile capacity can be determined using Shear Strength Parameters As per cluase of IS , the safe load capacity of pile can be determined as - Qu = C u N c x πd 2 /4 + α C s πd ls Where Qu Ultimate capacity of pile in compression, T D Diameter of Pile, m 0.6 Cu Shear Strength of rock below pile tip, t/m T/m 2 Nc Bearing Capacity Factor 9.00 Cs Average shear strength of rock adjacent to the shaft 0.10 in the socketed length, t/m α 0.90 Fs Factor of safety 6.00 Is Socket length, m 1.80 Hence Qu = Tons Hence,Ultimate load carrying capacity of pile = Qu = Tons Safe load Carrying capacity of pile = Qu/6 = / Tons say, safe load carrying capacity = 90 Tons

29 Project: Client: Soil Investigation and Topographical Survey for DHT Project at Visakha Refinery, Visakhapatnam Hindustan Petroleum Corporation Ltd. SFE Determination of Capacity of Pile (As per Cole & Stroud Approach) Using Cole & Stroud approach, capacity of bored piles in weathered and soft rock is given by Qap = [ (Cu. Nc. Ap) + α. Ca. π. D. L ] / FS Cu = Cohesion value at Pile tip = 100 T/m 2 Nc = = 9 D = Pile diameter = 0.6 m Ap = C/s area of pile = 0.28 sqm α = Reduction factor = 0.30 Ca = Cohesion along socketed length = 100 T/m 2 L = Socketted length of pile (3 times of dia) = 1.8 m F.S = For end bearing = 2.5 F.S = For skin friction = 3.5 Considering pile is resting on highly weathered/soft rock which is encountered at about m N value of highly weathered rock is observed as more than 100 for 5 cm penetration (bore log). Extrapolated N value for 30cm penetration will be more than 500. For calculation purpose, limit the N value to the possible lowest value of 150 From Cole & Stroud graph, for N value of 150, the corresponding shear strength value is 100 t/m 2. End Bearing Component (Cu. Nc. Ap) / F.S = 100 * 9 * 0.28 / 2.5 = 102 Tons Skin Friction α. Ca. π. D. L = = ( 0.30 * 100 * 3.14 * 0.6 * 1.8 ) / 3.5 = 29 Tons Total geotechnical capacity of pile = Tons = 131 Tons In some of the bore holes, very soft clay layer is encountered for a stretch length of about 1.5 m To 9.0 m. By considering the possibility of negative skin friction, the vertical load carrying capacity is limited to 100 Tons. Now, Uplift Capacity of pile Net Safe uplift resistance of piles = 70 % of safe skin friction (as per Tomlinson) = 0.70 * 29 Tons = 20 Tons

30 Project: Client: Soil Investigation and Topographical Survey for DHT Project at Visakha Refinery, Visakhapatnam Hindustan Petroleum Corporation Ltd. SFE Determination of Lateral Capacity of Pile (As per IS Part I /Sec 2) The lateral capacity of pile shall be evaluated based on the effective length of pile and for maximum deflection of 5 mm. Hence the safe lateral capacity of Bored cast-in-situ pile (Fixed Head Pile) can be determined as - Y = Q (L 1 + L F ) 3 / 12 EI Where Y Deflection of pile head 0.50 cm Q Safe Lateral Load Pile Capacity Tons L 1 Length of pile above ground level 0.00 cm L F Deph of point of contraflexure below GL Depends on R = (EI/k 2 ) 0.25 E Modulus of elasticity of concrete, 5700*sqrt(fck) in kg/cm kg/cm 2 fck Strength of concrete in kg/cm kg/cm 2 I Moment of inertia of pile cross section = π D 4 / cm 4 D Diameter of pile 0.60 meter K 2 From Table 2 of IS 2911, Part 1 / section kg/cm 2 R = (EI/k 2 ) cm Hence, from Table 2 of IS 2911, Part 1 / section 2 L F / R 1.90 L F Hence Y = Q (L 1 + L F ) 3 / 12 EI Now 12 E I = 2.18E+12 kg-cm 2 (L 1 + L F ) 3 = 4.10E+08 cm cm Hence, for Y = 0.50 cm Hence, Q = 0.50 * 2.18E+12 / 4.10E+08 = 2651 kgs Q = 3 Tons