Abstract: In order to meet the requirements of earthquake resistance and disaster prevention, seismic safety evaluation and analysis of tunnel structure are conducted. First, based on the characteristics of geological environment, tunnel structure, seismic force, and other factors affecting the tunnel seismic performance, the surrounding rock of composite strata is characterized through dividing strata groups. Second, the finite element timehistory analysis method is used to calculate the four mechanical performance parameters of lining, including transverse bending moment, shear force, axial force, and diameter deformation rate. Third, according to the strength and deformation requirements of lining materials, the safety factors corresponding to the above parameters are determined as the single evaluation index of seismic safety. Last, the seismic sensitivity value of the evaluation index is further analyzed as the weight to obtain the comprehensive evaluation coefficient, and a quantitative safety evaluation method for the seismic resistance of metro tunnel structure in composite strata is established. Through analysis on the engineering application, it is found that: (1) The diameter deformation rate and shear force are more sensitive to the seismic force level than the lining bending moment and axial force. (2) The lower the overall stiffness of strata group and the more uniform the strata distribution, the more conducive to the improvement of tunnel seismic safety.

Key words: composite strata, tunnel structure, seismic safety evaluation, seismic sensitivity value, comprehensive evaluation coefficient, diameter deformation rate