Cut and Cover tunnel was proposed along Domestic Airport T1 which has to be pass under the main airport road which was the entry point for Terminal 1D. so, to have a cut and cover tunneling activity proper deep excavation support to be maintained. Regulating the traffic through another direction could not feasible and needs to passed through this area.
Solution suggested by us:
Design and Installation of Cable Anchor, Rock Bolt and Shotcrete & Piling (King Post, Soldier Pile). The site is located near Airport T1 where requirement of deep excavation was arise. For this purpose Geo Spar is entrusted with the task to completing the work without much disturbance to moving traffic. Geo Spar visited the site and proposed cable anchors, rock bolts with shotcreting for supporting the sides of excavation. King post piles are installed over with steel platform is placed for keep traffic moving since the road is main access road. The choice of installation of places with anchor and rock bolt is made according to active earth pressure through analysis. The anchors are for temporary support which is retrieved after the placement of concrete structures. The anchor of capacity 68 and 45 ton were installed at 260 to horizontal at spacing of 3×3 meters. Designing team carried out design on the software for designing anchors, rock bolts and king post pile for taking loads and pressures properly without fail. After the design is complete Spar Geo execution team carried out execution of work by excavating and supporting the side as per the design. The work is executed by the Geo Spar execution team as per the design and on time. The anchors installed are retrieved after the placement of concrete structure the anchors are retrieved successfully without collapse by the Geo Spar.
Difficulties faced while execution:
Driving of king post into the rocky strata present on the site is very difficult as well as managing and diverting traffic while execution of work is a big task on its own.
Extra Technology used for execution:
The soil nails used are Resin grouted soil nails, in this type of soil nails resin capsules are inserted into predrilled holes. The insertion of nail in resin breaks the capsules forming a grout along the length of nail. This method provides higher strength. The anchors are retrieved after placement of concrete structures.
Multiple works were designed and installed at Cable Anchor, Rock Bolt and Shotcrete & Piling (King Post, Soldier Pile) by taking DMRC norms into consideration.