The Delhi Metro Rail Corporation Ltd. (DMRC) has issued Letter of Acceptance (LOA) to M/s Paras Railtech Private Limited for the Contract CC-126A: Construction of Cut and Cover tunnel box from Chainage 5050.35 (UP Line) to 5340.00 (UP line) for extension of Dwarka Najafgarh Metro Corridor of Delhi MRTS Phase-III at the total cost of INR 43.92 crore.
The work shall be completed within 04 months
In September this year, the DMRC had invited online open e-tenders for the work “Contract: CC-126A: Construction of Cut and Cover tunnel box from Chainage 5050.35 (UP Line) to 5340.00 (UP line) for extension of Dwarka Najafgarh Metro Corridor of Delhi MRTS Phase-III”.
Scope of work:
According to the tender document, the scope of work for this contract include Construction of Cut & Cover tunnel box and other Civil Works from Chainage 5050.35 (UP Line) to 5340.00 (UP line) for extension of Dwarka Najafgarh Metro Corridor of Delhi MRTS Phase-III. Excavation for the said work from Chainage 5050.35 (UP Line) to 5134.00 (UP Line) has already been carried out by the previous agency.
However excavated area measuring approx 90m for construction of cut and cover tunnel was backfilled due to settlement noticed in the adjacent building after heavy rain and ingress of water into the excavated portion.
The work includes construction of cut and cover tunnel box, Installation of Micro piling, stabilization of soil by injecting cement grout in the space between building line and soldier pile, excavation in confined space for tunnel construction, re-excavation of backfilled area by previous agency, fabrication and erection of temporary structural supporting arrangement, monitoring of adjacent buildings, waterproofing of Tunnel box, backfilling, road restoration, diversion/protection of utilities etc.
The construction of cut and cover tunnel box has to be done in close vicinity of shops and residential complexes, therefore special care to be taken during execution. The design of Permanent and temporary works for civil construction shall be provided by DMRC.
The Scope of works shall, inter-alia, include the following but not be limited to:
- The site clearance for the placement of the contractor’s own equipment, plant and machinery etc. to carry out the works before commencement of work or as directed.
- True and proper setting out and layout of works, bench marks and provision of all necessary labour, instruments and appliances in connection therewith as specified or directed.
- Construction of RCC Cut and Cover tunnel box by using Bottom up Technology including
- Waterproofing as per Tender drawing and Outline Construction specifications.
- The scope of work includes all civil works related to construction of cut and cover RCC tunnel box for above mentioned Chainage. However following works has already been executed by previous agency:
- Timber lagging in approximate 180 m length.
- Construction of RCC Tunnel Box from Chainage 5050.35 (UP Line) to 5107.00 (UP Line) except cut out in roof having size 20 m x 7 m.
- Construction of Base slab including side walls from Chainage 5254 (UP line) to 5275 (UP line).
- Installation of Soldier piles in entire section.
- Fixing of Temporary structure i.e. Wailer & struts from Chainage 5050.35 (UP Line) to 5134 (UP Line) and Chainage 5210 (UP Line) to 5300 (UP Line).
- Decking fixed in entire section however some deck panels have been removed.
- Installation of Micro piling and stabilization of soil with cement grout in the space between building line and soldier pile as per requirement or as directed by Engineer.
- Excavation in confined space as per drawing including fabrication and erection of temporary structural supporting arrangements. Re-excavation of area which was backfilled by previous agency.
- Monitoring of adjacent buildings, ground settlements, soldier piles, Strut and Wailer, kingposts etc. Preparation and submission of monitoring scheme and its approval from DMRC. Instrumentation scheme shall be implemented at site by appointing a specialized agency and the same is payable as per BOQ.
- Backfilling as per specification, road restoration, Construction of RCC box shape nallah (approx. 580m) and diversion/protection of utilities if any.
- Rectification of timber lagging damaged due to ingress of water in excavated area by fixing MS sheet/Timber lagging between soldier piles.
- Fixing MS sheet between Soldier pile for retaining of earth (New excavation).
- Retrieval of soldier piles, wooden lagging, strut and wailer, decking, king post, machineries etc. of previous agency including handing over of the same to the contractor of Contract CC-126.
- The works needs to be carried out adjacent to private buildings/shops. Special care should be taken while executing the piling and other construction works.
- Day to day cleaning of works, Maintenance of diverted roads and adjacent roads including deployment of Traffic Marshal, Traffic Signages etc. throughout the execution period.
- Clearing of site and handing over of all the works, as specified or as directed.
- Other Developmental works.
- Installation of construction decking to facilitate the excavation and other works.
Source: DMRC-Tender update | Image Credit: DMRC