Dynamic failure evolution of surrounding rock in a long tunnel with different unfavorable geological structure zones under non-uniform seismic input

Abstract

Earthquake damage investigations show that damage often occurs in complex geological sections with unfavorable geological structures along a long tunnel. And the unique earthquake damage phenomena are the result of non-uniform ground motion generally. In order to study dynamic failure evolution of surrounding rock in a long tunnel with different unfavorable geological structure zones under earthquake. Therefore, a variety of schemes for dynamic analysis of a long tunnel with different lithology and thickness unfavorable geological structure zones is carried out through non-uniform ground motion input. Firstly, based on stochastic process theory, multiple time history curves of different ground motions that can reflect the traveling wave effect and attenuation effect for long tunnels are generated. Then, the dynamic response of the surrounding rock in the tunnel is analyzed through inputting these non-uniform ground motions. By analyzing the variation of shear plastic strain increment and plastic volume in surrounding rock, the characteristics of the potential failure surface with the earthquake time history in the surrounding rock of the tunnel with different unfavorable geological structure zones are studied. On this basis, the main influencing factors and the degree of influence on the dynamic damage of the surrounding rock of the long tunnel with unfavorable geological structure zone under non-uniform ground motions are evaluated. The results show that the unfavorable geological structure zone has a controlling effect on the seismic dynamic response and destruction of the surrounding rock of the tunnel. Further, the lithology of unfavorable geological structures and the time history of ground motions have a significant impact on the response and damage of surrounding rock.