Application of isolation technology in shallow super-large comprehensive pipe galleries in seismically vulnerable areas with weak soils

Abstract Shallow urban tunnels with super-large sections in weak soils may experience much more devastating seismic hazards than conventionally deep tunnels in seismically vulnerable areas. This study investigates the seismic response and isolation technology for the largest comprehensive urban pipe gallery in the Xiong’an New Area, Hebei Province, China, using seismic simulation. First, the engineering background, static-seismic model, dynamic motions, and measuring points of the numerical simulation are introduced. Then, using the finite difference method to explore seismic behaviors of the super-large comprehensive urban pipe gallery under strong earthquake excitations are explored. The indexes including the deformation, the stress, the internal force, and the safety factor of segments are analyzed. Meanwhile, the aseismic effects of three proposed isolation schemes (namely, the cushion scheme, the partial buffer layer, and the integral buffer layer), which are proposed to be employed in the super-large comprehensive urban pipe gallery, are explored comparatively. The result shows that the integral buffer layer presents the most dramatic seismic isolation effect (97.85%), followed by the partial buffer layer (22.58%), and the cushion (15.07%). The integral buffer layer scheme is recommended to be employed in the seismic design for the present super-large pipe gallery. These conclusions can give scientific guidance for the seismic design of the super-large urban tunnels.