Study On Earthquake Responses And Vibration-Absorption Measures For Two-Tunnels Of Mountain Tunnel With Staggered Space

Underground structures are considered as better aseismic performance in contrast with surface structures because of the constraint of surrounding rock, so the seismic damage of underground structures is not paid much attention and the study of vibration of absorption and resistance of underground structures under earthquake is relative superficial. But much damage of underground structures under earthquake is reported. It is necessary to study the theory of vibration of absorption and resistance of underground structures under earthquake. Three pars are analyzed in the dissertation, as follows:First, the seismic damage of underground structures in home and aboard is investigated and the effect of stiffess matching among surrounding rock, aseismic layer and tunnel lining on the dynamic response of tunnels is studied by classical theory of vibration. The theory of vibration absorption and resistance of underground structures is dicussed and validated by finite element method. Then, five different earthquake waves are analyzed by the HHT time-frequency method and the relationship between the seismic response of tunnels and waves is discussed from the energy aspect.Then, several models are estalished based on the tunnel located in high intensity zone of southwest China, and the seismic response of portal structures of the tunnel with staggered space are studied by ABAQUS software. The trend of the Mises stress, maximum absolute and relative displacement and accelaration of transverse secion are analyzed. Based on the study, the seimic absorption effect of vibration absorption and resistance measures of two-tunnels of mountain tunnel with staggered space are discussed and analyzed considering the direction of earthquake load, and the relationship between design parameters of aseismic layer and effect of seismic absorption, the setup types of aseimsic layer and its absorption effect are obtained.In the end, large shaking table tests are performed for the two-tunnels of mountain tunnel with staggered space, and the seismic absorption effect of aseimsic layer measures are studied through the analysis of the tunnels cracks, acceleration, strain and ground cracks.