Study on dynamic response characteristics of high and steep layered rock mass slopes using a modal analysis method

Abstract

The common geological bodies found in southwest China are layered mass slopes. The modal analysis method is performed on four finite element numerical models of rock slopes, including the homogeneous slope, horizontally layered slope, bedding slope, and toppling slope to investigate the dynamic deformation characteristics of the layered slopes. Their dynamic deformation characteristics are systematically studied according to the modal characteristics of slopes. By using modal analysis, the numerical results show that a series of natural frequencies and vibration modes of the slopes can be obtained. The type of structural planes affects the natural frequency of the slopes. The values of the natural frequency of the slopes are as follows: homogeneous slope > toppling slope > horizontally layered slope > bedding slope. Weak structural planes also have an amplification effect on the dynamic deformation of the slopes according to the analyses of the relative displacement (U) of the first vibration modes of the slopes. The natural frequency has a significant impact on the dynamic deformation characteristics of the slopes. Low-order natural frequency mainly induces the overall deformation of the top slope and slope surface area, whereas the high-order natural frequency mainly induces the local deformation of the slope. Modal analysis can provide a new idea for further study of dynamic characteristics of rock slopes.