Study of Reinforcement Scheme for Tunnel Heaving due to Excavation of Sunken Plaza over Subway Tunnels

Abstract

The excavation of large area close to the top of the tunnel, is likely to lead to a big displacement and deformation of the tunnel, even endanger the safety of subways operation. Therefore, it has become a problem urgently to be solved that how to accurately predict and reduce the deformation of subway tunnel caused by excavation of sunken plaza. Build a numerical model in the finite difference software FLAC 3D, then according to the order of the construction organization, calculation and analysis four different reinforcement schemes in the process of the excavation of sunken plaza, the reinforcement schemes are Without reinforcement measures, adopt gantry soil-cement mixing pile reinforcement scheme, sinking square are at the bottom of the uplift pile reinforcement scheme and comprehensive use of soil-cement mixing pile of door and sinking square with uplift pile reinforcement scheme, then comparison and evaluation the effects of the four kinds of reinforcement schemes around the selected four indicators, they are the maximum vertical settlement of the tunnel, the maximum horizontal displacement value of the tunnel, the maximum convergence of a tunnel diameter and the minimum radius of curvature tunnel deformation curve .From the analysis, some conclusions can be drawn.