Abstract: To reveal the relationship between the acceleration response and the fracture expansion of the soft and hard interbedded steep slope due to strong seismic deformation action, centrifuge table tests were conducted and the Voronoi joint division method in universal distinct element code (UDEC) was used to replicate the deformation and failure process. The tension and shear fracture distributions in the slope affected by different amplitudes were traced based on Fish programming, and then the relationship between the fracture evolution and mechanical response was established on the basis of the marginal spectral entropy concept. The results show that: 1) The deformation and failure process of the soft and hard interbedded slope with steep inclination is as follows: top tension crack, bottom-slope-foot shear and whole failure. 2) At the initial stage of horizontal vibration load, the crack development is mainly affected by the tension, and with the increase in amplitude, the crack expansion is mainly caused by the combined tension and shear actions. 3) The variation of the marginal spectral entropy of the monitoring points in the slope body is closely related to the damage degree of the corresponding position. The marginal spectral entropy value increases when the damage of the slope is slight, whereas the marginal spectral entropy decreases with severer damage of the slope. 4) The deformation failure process of the slope body and the depth of the sliding surface can be determined based on the variation in the marginal spectral entropy value of each monitoring point.

Key words: soft and hard interbedded rock slope, UDEC, Voronoi, fracture distribution, marginal spectral entropy