Abstract：The seismic response characteristics of underground caverns are studied by employing dynamic time-history method. Based on the dynamic equilibrium equations of kinemato-dynamic time-history method and Newmark direct integration method，the computational codes are programmed by adopting three-dimensional elastoplastic finite element theory. The concepts of additional plastic load and additional damage load are considered to simulate the plasticity and damage of elements. The damage state of rock mass within each time step is inherited by subsequent time steps. Therefore，the irreversible trend of rock damage can be reflected. The incremental variable plastic stiffness iteration method is employed to solve dynamic equations. The calculation results show that the proposed iteration method has good convergence and fast computational speed. The iteration of each step can attain convergence within 3 steps. The way to setup boundary condition and the way to input dynamic loads are expounded by performing dynamic time-history analysis of large-scale complex underground caverns of Yuzixi hydropower station. The calculation results show that the computational speed of the proposed method in the codes is faster than that of common software. The calculation results are reasonable as well，which indicate that the proposed methods are rational and can be used to carry out dynamic time-history analysis of underground engineering.
