Abstract: The excavation of slope with different unloading rates is simulated with FLAC^3D finite difference method. The stress and strain of the slope in the presence and in the absence of unloading changes are compared and analyzed. Results showed that in the presence of excavation unloading, the stress and strain and plastic zone of slope model in the construction process are smaller when the excavation rate is slower; while when the dynamic unloading effect is not considered, the stress, strain, and plastic zone is not affected directly by the excavation rate. Therefore, the effect of dynamic unloading effect should be fully considered in actual construction, the excavation progress should be controlled, and the slope should be reinforced timely after the excavation.

Key words: rock slope, excavation rate, unloading, three-dimensional FEM, stability analysis