A Safe Bearing Capacity of Soil & Soil investigation

Transcription

1 A Safe Bearing Capacity of Soil & Soil investigation Rural Water Supply Scheme, Hanumangarh At 17 MSD, Inderpura, Hanumangarh By M/s Degremont Pvt. Ltd. Team Infrastructures (Soil & Construction Material Testing Laboratory) ISO 9001:2008 Certified Co. 184/16, Near Narayana Hardayla Hospital, Pratap Nagar, Jaipur(Raj.) India M

2 Name of Customer M/s Degremont Pvt. Ltd. Unitech Business park Tower-A, 2 nd Floor, South City -1 Gurgaon , Haryana - India 2. Letter No. & Date PO No. : Dated : Report No. TI/01/16/SBC/25-K 4. Name of Work Rural Water Supply Scheme, Hanumangarh. 5. Site Location 17 MSD, Inderpura, Hanumangarh 6. Name of Test SPT (SOIL) 7. Date of Sampling Date of Testing to

3 INDEX S. No Description Page No. 1. Introduction Safe Bearing Capacity 6 3. Soil Properties Calculation of Safe Bearing Capacity 9 5. Formula Chemical Analysis of Soil Conclusion & Recommendation References Site Photographs 14 Team Infrastructures Page 2 of 14

4 1. INTRODUCTION There is a proposal for construction of proposed Rural water Supply Scheme, Hanumangarh by M/s Degremont Pvt. Ltd. The report presented herein deals with the field investigation carried out to assess the nature of soil strata and other parameters required for foundation design of proposed structure. The work of soil investigation has been awarded to Team Infrastructures, 184/16, Pratap Nagar, Jaipur. The proposed site is located at 17 MSD, Inderpura, Hanumangarh. The objective of the present study was to carry out soil investigation so as to arrive at the parameters required for the design of foundations. For this, field investigations at the site were conducted. The results from these investigations have been analyzed in order to provide the required parameters. In order to achieve these objectives, the stipulated scope of work allotted to the consultants consisted of carrying out the following operations a. Transportation of plant and personnel to the site of work and withdrawing the same on completion of work. b. Drilling one boreholes of 100 mm diameter up to 2.0 m depth below ground level. c. Conducting Standard Penetration Test (SPT) in bore hole at 0.75m intervals or change of strata(as per client requirement) as per IS: d. Submission of report in duplicate with distinct recommendation for Safe Bearing Capacity of sub-soil strata type and depth of foundation. To execute the work as per given scope of work one boreholes of 100 mm diameter were drilled with the help of post hole augurs and other required machines. Standard Penetration Test were conducted as per IS The test was conducted in boreholes at regular intervals of 0.75 m. Standard split spoon sampler was attached to A rods and driven by means of a standard hammer of 63.5 kg falling freely from a height of 75 cm. The sampler was driven 45 cm. The no. of blows required for penetrating last 30 cm was taken as N value. Disturbed soil samples were taken from the boreholes for laboratory analyses purpose. Team Infrastructures Page 3 of 14

5 SCOPE OF WORK The scopes of the soil investigation were: A. To explore the sub- surface conditions of the proposed development area and to provide general data relating to the project. B. To carry out field standard penetration test (SPT- 63.5kg hammer having a free fall to 750mm) to determine the natural bearing resistance of the sub soil for the purpose of design. C. To obtain disturbed and/ or undisturbed soil sample for carrying out the laboratory tests to determine the natural and relevant physical properties of the sub soil pertaining to. TEST PERAMETRS FIELD TESTS 100mm dia. bore hole was advanced up to the desired depth below the ground level. Boring was associated with collection of SPT samples and SPT tests were conducted at 0.75m interval (As per client requirement). After collection from bore holes the samples were sealed and transported to the laboratory carefully in the due time. LABORATORY TESTS The soil samples collected from all the bore holes were tested in the laboratory. The following tests were conducted and analyzed for determination of certain engineering properties and its bearing capacity. (i) (ii) (iii) (iv) (v) Specific gravity Grain size analysis Bulk density Atterberg s limits Direct shear test SPECIFIC GRAVITY Specific Gravity of Soil particles is the ratio of the weight in air of giving volume of soil to that of water at 27 0 c. Specific gravity of soil is determined as per is 2720 (part III) values of specific gravity of soil samples are mentioned in the investigation sheet. Team Infrastructures Page 4 of 14

6 GRAIN SIZE ANALYSIS The Soil Aggregate Comprises on the particles of different sizes of different proportion. For classification of soil met at various depths in the bore holes grain size analysis were conducted as per IS 2720 (part-v). A result of grain size distribution has been reported in the laboratory Investigation sheets. The soil has been classified as per IS INDEX PROPERTY Soil Consistency Refers to the Resistance of the soil offers against the forces that deform the soil aggregate consistency limits which indicate the soil moisture content limits of various states of consistency. These limits are also known as atterberg s limits, liquid limit, plastic limit of soil samples were determined as per IS2720 (part-v) STANDARD PANETRATION TEST: In The field standard penetration test (SPT) was done. The SPT sampler tube of 38mm odx450mm long thick walled driven in the soil under the impact of the sliding hammer weighing 63.5kg having a free fall from 750mm height. The penetration resistance of N value is recorded as the number of hammer blows required to achieve a penetration of 300mm or 50 hammering after the initial penetration of 150mm ( to allow of any disturbed materials at the bottom of the bore hole). In dense sands, very hard clays or weak rock, the full 450mm penetration may not be practicable and the test is discontinued. After the completion of the test, the sampler tube is removed and disassembled to provide a disturbed bore representative sample. Team Infrastructures Page 5 of 14

7 2. SOIL INVESTIGATION & TEST REPORT Safe Bearing Capacity (One bore hole) Depth in Meter Safe Bearing Capacity Settlement Criteria (t/m 2 ) Local Shear Criteria (t/m 2 ) Recommended Safe Bearing Capacity (t/m 2 ) Soil is cohesion less loam up to 2.0 m depth. It is loose up to 2.0 m depth. Soil is suitable for laying foundation. Team Infrastructures Page 6 of 14

8 3. SOIL PROPERTIES RECORD OF BORING - BH-1 Project - : Rural water Supply Scheme Date of Starting : Bore Hole No. : 1 Date of Completion : Depth of Borehole : 2.0 m Location : 17 MSD, Inderpura Dia./Size of Borehole : 100 mm Depth of GWT : 75 Ft. Description of Strata Bore Log Depth from ground surface in meter Samples Type No. of Blows Related to Depth of Penetration I II III "N" Value Loam 0.75 S/DS Loam 1.50 S/DS Loam 2.00 S/DS R-Refusal (N >50) N Value=Penetration Resistance UDS Undisturbed Sample DS Disturbed Sample S- Standard Penetration Test Team Infrastructures Page 7 of 14

9 RESULTS OF LABORATORY TEST Soil Properties for bore hole 1 Depth (m) S. No Soil Property Silt & Clay (%) Fine Sand (%) Medium Sand (%) Coarse Sand (%) Gravel (%) Sp. Gr Liquid Limit (%) Plastic Limit (%) NP NP NP 9. Plasticity Index (%) Cohesion kg/cm 2 CL CL CL 11. Angle of Internal Friction ϕ Av. Bulk Density(gm/cc) Note: NP Non-Plastic CL Cohesion less Soil is loam up to 2.0 m depth, primarily consists of silt and fine sand (97 to 98%). It is non-plastic and cohesion less up to 2.0 m depth. Soil is loose up to 2.0 m depth. Rock was not encountered up to 2.0 m depth. Water table was not intersected up to 2.0 m depth. Team Infrastructures Page 8 of 14

10 4. SAFE BEARING CAPACITY LOCAL SHEAR CRITERIA Depth (m) Width (m) Av. Bulk Density D Cohesion T/m 2 Angle of Repose Ǿ Ǿ N c N q N r Q nf (t/m 2 ) Q ns (t/m 2 ) Q s BH Note: Ǿ - Angle of Repose N c - N Q -N r -Bering Capacity Factor Q nf - Net Ultimate Bearing Capacity Q ns - Net Safe Bearing Capacity Q s - Safe Bering Capacity Safe Bearing Capacity 25 mm Settlement Criteria Depth (m) Bulk Density gm/cc D 'N' BH 1 Corrected 'N' Qns T/m Qs T/m Note: Ǿ - Angle of Repose N c -N Q -N r -Bering Capacity Factor Q nf -Net Ultimate Bearing Capacity Q ns -Net Safe Bearing Capacity Q s -Safe Bering Capacity Team Infrastructures Page 9 of 14

11 5. FORMULA IS-8009(part-I)-1976 The safe bearing pressure can be calculated using readymade chart for any value of permissible settlement, given width of footing and corrected value. IS The following formulae have been used for calculating ultimate net bearing capacity as per IS : Local Shear Failure Criterion- Qnf = 0.67cNc sc dc ic + q (Nq-1) sq dq iq B N s d i w Where N c N q N = Bearing capacity factors C= Unit Cohesion B= Width of strip footing s c s q s = Shape factors = Bulk unit weight of foundation soil Q nf = Net ultimate bearing capacity based on local shear failure w = Correction factor for location of water table * Note- Factor of safety equal to 3 has been used to calculate net safe bearing capacity, to obtain safe bearing capacity D has been added to net safe bearing capacity. Team Infrastructures Page 10 of 14

12 6. Chemical Analysis of Soil Depth (m) ph Chlorides % Sulphate Content (SO 4 )% Organic matter content % Chemical analysis reveals that chlorides and sulphates present in soil are well within safe limits and therefore no preventive measures are required. Team Infrastructures Page 11 of 14

13 7. CONCLUSION & RECOMMENDATIONS Soil is loam consisting mainly of silt and fine sand (97 to 98 %). It is non-plastic and cohesion less up to 2.0 m depth. Soil is loose up to 2.0 m depth. Rock was not encountered up to 2.0 m depth. Water table was not intersected up to 2.0 m depth. Soil is suitable for laying foundation. ******* Note: Results related only to the sample (s) under test in as received condition and applicable parameter (s). This test report shall not reproduced wholly or in part and cannot be used as evidence in the court of law without written approval of M/S TEAM Infrastructures Jaipur. Balance samples, if any shall be discarded after three month from the date of issue of report. Team Infrastructures Page 12 of 14

14 8. REFERENCES CODES & STANDARDS IS: Standard Penetration Test IS: 2720 Part II - Determination of Moisture Content of Soil IS: 2720 Part III - Determination of Specific Gravity of Soil IS: 2720 Part V - Determination of Liquid Limit and plastic Limit of Soil IS: 2720 Part IV - Grain Size Analysis of Soil IS: 2720 Part XIII - Direct Shear Test IS: Indian Classification System Team Infrastructures Page 13 of 14

15 9. SITE PHOTOGRAPHS Team Infrastructures Page 14 of 14