Abstract: In this paper, based on the rock slope conditions of the final mining boundary in one open pit metal mine, the strength reserve safety factor of slope in natural condition is calculated by using the software of FLAC3D and the method of strength reduction. In order to analyze the dynamic stability of slope under different strength reduction factors, the explosive dynamic loading is applied on open pit bottom of -50 m level as the form of normal compressive stress by using the measured data. Meanwhile, the nonlinear theory of load-unload response ratio (LURR) is introduced to analyze the dynamic stability of slope, and the LURR model of slope under the explosive dynamic loading is then established. By considering the periodical variation of additional explosive loading at different feature points of slope as the load-unload amount, and the deformation of corresponding feature point as the response parameter, the LURR of slope feature point during the action process of explosive loading is then determined. The calculation results show that the LURR value of the feature point is near 1 when the slope system is stable, and it is gradually increased as the slope approaching instability. The LURR variation law men-tioned above presents that it is feasible to use LURR as the judgment basis of slope stability influenced by explosive loading. It also can extend the analysis function of strength reduction method, which is worth popularizing and has important theoretical significance.

Key words: explosive dynamic loading, slope of open pit, load-unload response ratio, numerical simulation