Seismic Isolation Of The Multi-storey Building Subjected To Blast Loading In Underground Tunnel

When the intense explosions takes place in underground tunnel, all kinds of aboveground structures will generate severe damage even collapse. Consequently, both domestic and foreign researchers pay more attention to the shock isolation and reduction of all types of buildings subjected to explosive loading. In this paper, the shock isolation and reduction of some types of multi-storey structures subjected to explosive loading in the underground tunnel is investigated numerically. The primary work and achievements are as follows.(1) The explosive-atmosphere-lining coupling models are established using ANSYS/LS-DYNA software to simulate exploding process in the underground tunnel and the overpressure history on the inner surface of tunnel is obtained. ANSYS/LS-DYNA software is used to build the three dimensional model including the tunnel, soil and aboveground multi-storey building (consist of frame structure with raft foundations, frame-shear walls structure with raft foundations and frame structure with pile foundations), and the semi-infinite soil foundation is simulated by using non-reflecting boundary. The feasibility of using the pile-soil composite material element in the anti-explosion analysis is attempted and the shock isolation effects of a sand layer and rubber bearings on the structure are paid more attention.(2) Because of frame-shear structure has good integrity and lateral stiffness, its response is smaller than frame structure under the explosion load. To the frame structures with raft foundations, frame-shear walls structures with raft foundations, numerical results demonstrate that using a sand layer is effective to reduce the structural response and damage to blast induced ground motions in high frequency and the isolation effect increases with the increase of thickness of sand layer. It has a good effect for the thickness of 0.8 meters to absorb energy of high frequency explosion wave and reduce the explosion energy of the delivering to the structure.(3) Through the comparison of the dynamic response of structure, with and without rubber isolation bearing, among the frame structure with raft foundations, frame-shear walls structure with raft foundations and frame structure with pile foundations, it is found that the rubber isolation bearing can reduce the whole building deformation, acceleration and MISES stress effectively. As a kind of base isolation, the rubber isolation bearing can increase the ductility of the building, and make the upper structure and foundation separated effectively, which is benefit to the structure anti-explosion.