Longitudinal seismic design of T-type underground precast utility tunnels

Based on the response deformation method, a longitudinal seismic design method for underground cross utility tunnels is proposed. By changing the phase angle of the displacement function, which deforms the site for one period, the periodic ground deformation input is realized. The deformation history of T-type precast utility tunnels is analyzed, as well as the most unfavorable modes for structural deformation and internal forces around the cross node. Through the orthogonal test analysis, the seismic responses of the T-type underground utility tunnels under different site parameters and seismic input parameters are studied, as well as the sensitivity analysis for the most unfavorable modes. The results show that the periodic ground deformation input can catch the most unfavorable modes of structural deformation and internal forces, and the incident angle of seismic wave controls the most unfavorable modes of structural deformation and internal forces. The proposed method can be directly used for the longitudinal seismic design of underground cross structures.