Studies on Aseismatic Performance of a Typical Subway Tunnel with Initial Defects Caused by Construction of New Down-Through Tunnels

摘要

For the engineering background of subway tunnel with initial defects caused by the construction of new down-through tunnels, the aseismatic performance of the existed tunnel is studied so as to reveal the mechanism of seismic dynamic response by using finite difference method.Numerical simulation shows that the tunnel is deforming in its entirety since such physical variables as velocity, displacement and stress in its all key weak points have same dynamic tendency under influence of approaching construction of tunnels, and these variables are much larger than those without any influence.After down-through construction, much influences of aseismatic performance are mainly taking place at both the side wall and the upper arch, and the shearing damage are mainly doing in surrounding soil mass.Due to widely shearing damage after down-through construction, it is suggested that grouting reinforcing should be applied so as to make them much stiffness as a whole.