The Delhi Metro Rail Corporation Ltd. (DMRC) has issued a Letter of Acceptance (LOA) to M/s. Cengrs Geotechnia Pvt Ltd for Geotechnical Investigation work for preparation of DPR for Metro Corridor from Greater Noida KP-II to Noida International Airport.
- Tender Reference Number: NIT/02/GM/CS/2021-22
- Name of Work: Geotechnical Investigation work for preparation of DPR for Metro Corridor from Greater Noida KP-II to Noida International Airport.
- Work Completion Period (in days): 70
- Contract Value: INR 11.72 Lakh
In October this year DMRC had invited a tender for Tender Reference Number: NIT/02/GM/CS/2021-22.
Scope of Work:
The work mainly comprises of Geotechnical Investigation work for preparation of DPR for extension of Metro Corridor from Greater Noida KP-II to Noida International Airport. (35.64 km approx.). The project site is located in the area of Greater Noida. Activities to be performed are as follows:
- Drilling of 150 mm diameter boreholes in all types of soils upto 30 m depth.
- Conducting Standard Penetration Tests in boreholes at regular intervals of 1.5m as per I.S. Code of practice and also in-situ tests as per Schedule.
- Collecting undisturbed soil samples from bore holes at every change of strata subject to a minimum of two per borehole as per I.S. Code of practice.
- Recording of water table level in the boreholes after completion of boring.
- Drilling bore holes upto a maximum depth of 5 metres in intact Hard Rock (RQD >50%) or 10 m in weathered rock (RQD upto 50%) or 30 metres in soil (upto N=100) using hydraulic / calyx rig by wash boring method as per the directions of Engineer-in-charge and as detailed in Technical Specifications and Schedule.
- Conducting in-situ permeability tests in Rocky strata and tests in labs in all other types of soils.
- Collecting rock core samples from bore holes and recording the RQD.
- Conduct all necessary laboratory tests on samples collected as per Schedule and Technical Specifications.
- Survey of bore holes for elevation and plotting of bore hole locations in alignment plan.
- Preparation of report summarizing the details of soil / rock classifications, analysis of test data and recommending the type of foundations to be adopted with design calculations for the proposed Elevated corridor duly highlighting the design criteria and design methodology and different groups of soil strata encountered.
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 enclosed in Section-6.0. The cost of providing, maintaining, shifting etc. of barricading shall be borne by the agency.
- All boreholes shall be extended upto depths of 30 m 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 the bore hole does not exceed 30 m. 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 the 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.
About Cengrs Geotechnia:
- Cengrs is one of the leading Geotechnical Engineering Consulting firms in India.
- Established in 1990, and led by a team of IIT Delhi graduates, they have successfully completed over 6000 projects across India and abroad.
- Powered by over three decades of technical expertise and experience, they, at Cengrs, are fully adept at conducting the full range of ground investigations, data review & interpretation, and engineering analyses pertaining to the Geo-technical domain.
- With a line-up of state-of-the-art equipment and other allied resources, they provide a comprehensive suite of services, which include Geotechnical Investigations, Topographical and Hydrographical Survey, Laboratory Testing, Foundation Testing, Foundation Construction, and Ground Improvement.
Source: DMRC-Tender Update | Image Credit (representational): DMRC
