Abstract: The seismic response of subway tunnels is studied by introducing random field theory and considering the spatial variability of soil mechanics parameters. Based on FLAC3D finite difference software, the numerical model of a subway tunnel with liquefiable soil layer below was established. It is found that under the assumption of homogeneous soil the deformation of the tunnel is quite different from that of the arch and the arch waist, and the overall displacement of the tunnel occurs in the horizontal direction. While the seismic response of tunnel considering the spatial variability is much larger than that of the above deterministic calculation which shows that the traditional assumption of homogeneous soil overestimates the safety of the tunnel under earthquake.

Key words: liquefiable soil, tunnel, random field, dynamic response