INTEGRAL RESPONSE DISPLACEMENT METHOD FOR LONGITUDINAL SEISMIC ANALYSIS OF LARGE-SPACE TUNNEL STRUCTURE

The seismic response of large-space underground tunnel has two main characteristics. Firstly, the seismic propagation direction is usually not perpendicular to the longitudinal axis of the structure, thus the seismic responses of the tunnel are different along its longitudinal axis at the same time. Secondly, the structural shear deformation becomes more significant with the increase of cross-section size. However, existing pseudo-static methods are mostly two-dimensional analysis method for lateral seismic response of large-space underground structure subjected to vertical-incidence seismic waves, which are not applicable for the longitudinal seismic response analysis of tunnels. The above computational limitation can be addressed to a certain extent by using the longitudinal integral response displacement method proposed based on the Euler beam theory. Although this method can be adopted to calculate the most unfavorite response of the tunnel under asynchronous seismic wave, it is difficult to reasonably describe the shear deformation characteristics of the large-scale underground structure. Based on the features of the longitudinal seismic response of large-space tunnel, combined with Timoshenko beam theory, a method for determining the most critical moments of longitudinal seismic response of large-space tunnel is proposed. On that basis, an integral response displacement method for longitudinal seismic analysis of large-space tunnel structure is developed in this study. The effectiveness and accuracy of the proposed method are verified by numerical examples.