Optimization of soil improvement for seismic isolation design of urban tunnels

摘要

This paper presents a numerical procedure to find out the optimal soil improvement method that isolates earthquake force to the tunnel structures. The procedure utilizes the changing of earthquake responses of tunnel and the surrounding ground accompanying the soil improvements. By combining dynamic finite element method in time domain and mathematical programming techniques, the procedure allows to modify the shear wave velocity and damping coefficient of the improved area until dynamic safety factor of the tunnel structures increasing sufficiently. Firstly, the procedure is applied to hypothetical case studies and its validity is confirmed. Subsequently the trial application of the procedure to actual case studies is discussed.