Anti-seismic Analysis and Optimization Design of Nuclear Power Water Intake Tunnel with Different Section Types

Combined with a nuclear power project in Pakistan, three types of tunnel sections are applied to the water intake tunnel model of Karachi nuclear power plant in Pakistan. The seismic response calculation is realized by using time history analysis method and finite difference software, and the section is optimized by using the calculation results. In the calculation, two different working conditions are used, considering the water pressure and supporting effect in the tunnel. Through the comprehensive analysis of the internal force and deformation of the three types of sections, the guidance is provided for the seismic design of similar projects. The results show that the bending moment and shear force of circular section are smaller than those of the other two sections. The internal force distribution of the three is basically similar, and the numerical value of some areas changes greatly, but the internal force distribution of the circular section is the most uniform and the stress is the most sufficient. Through the optimization and comparison of the three cross-section forms, the circular cross-section form has the lowest cost under the condition of meeting the seismic requirements, but the water flow of the circular tunnel is smaller than that of the horseshoe and the gate tunnel, and it is more difficult in the excavation process than that of the horseshoe. According to the actual geological conditions, two types of cross-section, i.e. circular section and horseshoe section, should be considered. The research results of this paper may provide reference for similar tunnel seismic design.