An Innovative Method of Large Space Underground Construction in Soft and Shallow Ground Using Concrete Arch Pre-Supporting System, CAPS Method

Construction of underground structures in urban areas is a very challenging work. There are generally two methods of their construction, an open cut-and-cover and underground method. To eliminate the subsurface and surface disturbance and street traffic problems, underground method is preferred. The stress redistribution caused by underground excavation induces movements in the earth mass and ultimately at the ground surface. This is more pronounced in large space excavations. Generally pre-supporting system is used to control ground deformation and thus enhance its stability. In this paper an innovative pre-supporting system is presented. Concrete Arch Pre-supporting System (CAPS) is introduced in Tehran Metro in 2002. This method has roots in construction method of an Old Iranian small water tunnels, called Quanat. CAPS is an efficient method for stabilizing large span underground spaces constructed in shallow and soft ground. In this technique underground reinforced concrete elements are constructed around the proposed underground space prior to main excavation. This method is used successfully in over 50 large span underground structures in Tehran Metro. CAPS has a potential to be used to pre-support the large span underground spaces at any weak ground condition in an urban area.

کلیدواژه ها:

Large Span Underground Spaces ، Subway Stations ، Concrete Arch Pre-Supporting System ، CAPS ، Numerical Modeling