Numerical analysis of damping structure of deep buried tunnel crossing fault zone

Tunnels have suffered serious damage in active fault and fracture zones during earthquakes in recent years. Seismic design of tunnel lining structure becomes particularly prominent. In order to reduce the damage of the tunnels by fault displacement, a piece of advice for the seismic design is proposed, that is, it is composed of smooth layer, absorbing layer, joint and friction- eliminating layer. Based on the analysis of seismic response results of tunnel structure using high compactness concrete (water cement ratio of 50%) as the absorbing layer, as well as using foaming styrene (EPS) as the absorbing layer, conclusions are drawn as follows for the case of using foaming styrene (EPS) as the absorbing layer, the initial stiffness is low, the damping effect is obvious, but too much displacement may happen under the train load. For the case of using high compactness concrete as the absorbing layer, the layer possesses the ability absorbing fault displacement after full yield, and the stiffness to restrain oversize displacement may happen under the train load. By changing spherical shell type, filling ratio, mortar proportioning of high compactness concrete, the stiffness can be changed. The water cement ratio should not be too high, which may cause compression strength of mortar not to bear the train load and tunnel structure damage. The water cement ratio of 50% is satisfactory under the fault displacement of less than 1.0 m.