Delhi Metro Rail Corporation (DMRC) has invited tender for the work of Geotechnical Investigation for Patna Metro Depot of Patna Metro Rail Project.
- Tender Reference Number: PMRC/Geo-Tech/Corridor-2/Depot
- Name of Work: Geotechnical Investigation for Patna Metro Depot of Patna Metro Rail Project.
- Approximate cost of work: INR 14,41,160.165 /-
- Completion period of the Work: 03 Months
- Document Download / Sale Start Date: 07-Mar-2022
- Document Download / Sale End Date: 06-Apr-2022
- Pre Bid Meeting Date: 16-Mar-2022
- Bid Submission Start Date: 25-Mar-2022
- Bid Submission End Date: 06-Apr-2022
- Bid Opening Date: 08-Apr-2022
Technical Specifications:
Soil Investigation:
Boreholes:
- Boreholes shall be sunk at specified locations to obtain information about the sub- surface soil, and to collect soil and rock samples for strata identification and laboratory testing. The minimum diameter of borehole shall be 150 mm in soil and NX size(75 mm dia.) in rock and the boring shall be carried out in accordance with the provisions of IS 1892 and as per specification. Bore holes shall be advanced using water or bentonite. No slush should be allowed to flow on the road. If any slush is there, the same should be cleaned during and after completion of boring. Casing may be necessary to maintain the sides of the boreholes in a stable condition. Rock boring shall be carried out using a double core barrel / triple tube having a diamond bit to get higher core recovery. Necessary barricading with 2.4mx1.8m metallic/wooden boards with necessary fixing / supporting arrangements shall be made around the work area. The barricades shall be provided with wheels for easy shifting and movement. The barricading panels shall be light/movable and shall be as per Sketch No. DMRC/20/Chandigarh/ GEO/2010 enclosed. The cost of providing, maintaining, shifting etc. of barricading shall be borne by the agency.
- All boreholes shall be extend upto depths of 40m in soil (upto N>=100) or 10 m in weathered rock (RQD <=50%) or 5 m in hard rock (RQD>50%) unless otherwise directed by the Engineer. However the maximum depth of bore hole does not exceed 40m. If strata having a standard Penetration Test value greater than 100 with characteristics of rock, is met with earlier, the borehole shall be advanced further by boring with approval of the Engineer. When the boreholes are to be terminated in soil strata, the Standard Penetration Test shall be carried out at the termination depth and recorded.
- Casing shall be used in the boreholes to support its sides, if required. When casing is used it shall be ensured that its bottom end is, at all times, less than 150 mm above the bottom of the borehole. In case of cohesion less soil, the advancement of the casing shall be such that it does not disturb the soil to be tested or sampled. The casing shall be advanced by slowly turning the casing pipe and not by driving. Casing can be withdrawn after inspection of bore hole by the Engineer with his approval. No extra payment shall be made for providing the casing.
- In-situ tests shall be conducted and undisturbed samples shall be obtained at specified intervals in the boreholes. Representative disturbed samples shall be preserved for conducting various identification tests in the laboratory. Water level shall be determined in the boreholes and shall be carefully recorded on the drilling log.
- The borehole shall be cleaned, using suitable tools up to the depth of testing or sampling, ensuring that there is minimum disturbance of the soil at the bottom of the borehole. The process of letting through an open tube sample shall not be permitted. In cohesive soils, the borehole may be cleaned by using a bailer with a check valve.
Rotary Drilling:
- Rotary method can be used in all types of soil below water table. In this method, boring shall be done by rotating the bit fixed at the bottom of the drill rod. Proper care shall be taken to maintain contact between the bit and the bottom of the borehole at all times. Use of percussion tool shall be permitted in hard clays and dense sandy deposits.
Water Level Measurement:
- The water level in the borehole shall be carefully recorded and reported, when first encountered whilst drilling the water level shall be measured every morning before recommencement of the drilling activities.
In-Situtests:
- Standard Penetration Tests:
- SPT tests shall be conducted in all types of deposits at 1.5m intervals or as per direction of engineer in charge. The tests shall be carried out by driving a standard split spoon by meansof 63.5kg hammer (140 lbs) having a free fall of 76 cms(30 inches). Detailed procedure for testing as specified in IS 2131 shall be followed. The samples obtained in this split spoon shall be placed in an airtight jar or equivalent, leveled and preserved for identification tests in the laboratory.
- Water Samples:
- Samples of ground water shall be obtained from each bore hole when first
- encountered or unless specified otherwise.
- At the specified depth, water shall be pumped out so that fresh ground water flows into the borehole. Care shall be taken in avoiding any contamination with surface water at any time. Water samples shall be collected in 5 litre polythene or glass container and labeled properly.
- Field Permeability Tests:
- Field Permeability Tests shall be conducted, if required to determine the water percolation capacity of overburden soil. The specifications of the equipment required for the tests and the procedure of testing shall be in accordance with IS 5529 Part-1.
- Constant Head Method:
- This test shall be conducted in boreholes where soils have high permeability. Water shall be allowed into the borehole through metering system ensuring gravity flow constant head so as to maintain a steady water level in the borehole and reference mark shall be done at a convenient level, which can be easily seen in the casing pipe to note down the fluctuations of water level. The fluctuations shall be counteracted by varying the quantity of water flowing into the borehole. The evaluation of water shall be observed at every 5 minute interval. When 3 consecutive readings show constant value, the necessary observations such as flow rate, evaluation of water surface above test depth, diameter of casing pipe etc. shall be made and recorded as per the proforma recommended in IS : 5529 Part-1Appendix-A.
- Falling Head Method:
- This method shall be adopted for soils of low permeability and which can stand without casing. The test section shall be sealed at the bottom of borehole and a packer at the top of the test section. If the test has to be conducted at an intermediate section of a borehole, then double packers shall be used. Access to the test section through the packers shall be by means of a pipe, which shall extend to above the ground level. Water shall be filled in the pipe upto the level marked just below the top of the pipe and water allowed to drain into the test section. The water level in the pipe shall be recorded at regular intervals as mentioned in IS: 5529 Part-1 appendix-B. The test shall be repeated till constant records of water level are achieved.
- Resistivity Tests:
- The electrical resistivity shall be conducted to determine the subsurface resistivity by making measurements on the ground surface. The measurement of electrical resistivity shall be conducted using four electrodes placed in contact with the surface material. The geometry,
- separation of the electrode array and spacing are to be selected on the basis of the application and required depth of investigation. The specifications of the equipment required for the tests, the procedure of testing and electrode array geometry shall be in accordance with IS 15736.
- Plate Load Tests:
- The deformation modulus (Ev2) shall be conducted to check the suitability of various components of the Formation layer (blanket, subgrade) and of subsoil for laying tracks. The test shall be done as per RDSO Specification No. RDSO/2020/GE: IRS-0004 & DIN 18134 – April 2012.
Tender document can only be obtained online after registration of tenderer on the website https://eprocure.gov.in/eprocure/app.
Source: DMRC-Tender
