Abstract：The mathematic models of seismic responses used for analyzing submerged tunnels are utilized to study the stochastic seismic responses of underground structures. The principles and methods of computing the impulse-response function for the underground structures with dynamic analysis method are elaborated，and the formulas for evaluating the statistical characteristics of the longitudinal stochastic seismic responses for underground structures are achieved by using principles of Fourier transform and theories of random vibration. With stochastic seismic responses considered as a Poisson process，the formulas for calculating the longitudinal aseismic reliabilities on the basis of the first passage mechanism are established. The Nanjing Changjiang Tunnel is used as an example to compute the square-mean-root responses and the longitudinal aseismic reliabilities under stationary random earthquake loads. A new analysis method proposed in this paper can serve as the theoretical basis for the speculation standards of the stochastic aseismic design for underground structures based on reliability theories.
