Innovative Skidding Mega Truss Shoring System

The construction of submerged tunnels at marine areas is a difficult challenge faced by both Contractor’s and Designer’s as the excavation and tunnel construction works will be carried out over water exposing workers to safety risks for marine works and the costly logistical planning required. To overcome this challenge, the proposed cut and cover tunnel with clutched pipe pile (CPP) wall cofferdam would use an innovative method where mega trusses are proposed as struts for the first and second shoring layers and also double function as support for the hanging kingposts. The trusses would be transported by barge in modules and assembled on the bulkhead temporary working platform as on-site assembly factory. Once mega truss is assembled, strand jack lifting towers will lift each mega truss onto the skidding rails installed along the top of the CPP cofferdam wall where hydraulic jacks will skid each truss in a sequence of small strokes along the rails until they reach their final position and this process is repeated for all trusses. The use of the mega truss skidding system increases the productivity and cost effectiveness of both the installation and dismantling of the ELS works in addition to reduction of the safety risks and complexity of erecting steel works above water.