Seismic response analysis of coal mine shaft tower structure considering PSSI effect under different sites

Traditional shaft tower structural design methods typically assume a rigid foundation, neglecting the impact of pile-soil-structure interaction (PSSI) on the seismic response analysis. This simplification often results in designs that are either overly conservative or fail to meet safety requirements. Therefore, a thorough study of the seismic response of shaft towers under the influence of these interactions, particularly in terms of inter-story displacement and internal forces, is crucial and significant. Using a substructure analysis method, based on the Winkler foundation beam model and the Penzien concentrated mass model, and integrating three-dimensional wave theory with dynamic foundation half-space theory, a simplified theoretical analysis model for the rigidly connected piled raft foundation shaft tower system was proposed. Moreover, the system’s theoretical equations of motion within the time domain were established, and MATLAB was utilized to develop a solution program using the Runge-Kutta method. Based on this simplified theoretical model and theoretical equations of motion, a comparative analysis between rigidly connected piled raft foundation shaft towers and rigid foundation shaft towers was conducted, using a specific large mine shaft tower structural system as the study subject. A systematic study was performed to explore how different site categories (Types II, III, and IV) and various seismic waves affect the seismic response analysis of shaft towers, revealing the patterns of influence from the PSSI. The results show that, compared to rigid foundation shaft towers, considering these interactions results in enhancement coefficients for inter-story displacement in Types II, III, and IV sites concentrated at 1.31–1.61, 0.89–1.25, and 0.74–0.97, respectively. Due to the differences in site categories of Type II, Type III, and Type IV, the enhancement coefficients for inter-story displacement vary, and the softer the site, the smaller the enhancement coefficient. Since inter-story displacement directly reflects the magnitude of internal forces within structural components, it is recommended that the impact of these interactions be considered in the engineering design and seismic response analysis of rigidly connected piled raft foundation shaft towers.