Large scale shaking table model test and analysis on seismic response of utility tunnel in non-homogeneous soil

Underground utility tunnels are the most fundamental and reliable lifeline network in urban cities, and are widely constructed throughout the world. In urban areas, most utility tunnels usually encounter the non-homogeneity of subsoil condition due to various construction effects. Studies have shown that the damage mechanism of shallow underground structures mainly depends on the inhomogeneity of the subsoil conditions. This would become a considerable factor for the stability of the underground utility tunnel structures. However, this type of research still needs to establish the vulnerable seismic design. In this study, a series of shaking table tests were conducted on non-homogenous soils to investigate the performance of seismic interaction between utility tunnels, surrounding soils and interior pipelines. The dynamic responses measured from the test account for the boundary condition of non-homogeneous soils, the internal forces, displacement of tunnel joints, the dynamic characteristics on interior pipelines and the reasonable spring stiffness with damping in the seismically isolated gas pipeline model inside the tunnel. The vulnerability of underground utility tunnel in non-homogeneous soil zone and the mechanism of the stability of interior facilities are the main topics discussed in this paper.