Abstract: The strength property of the intermittent jointed rock mass is an important factor which affects the safety of large slope and tunnels. With the increasing degree of environmental degradation induced by the acid rain, pollution and other factors, it is necessary to study its influence on the mechanical properties of intermittent jointed rock mass. Based on the existing bond contact model, a novel bond contact model, in which the process of environmental degradation was simplified ultimately as the constantly dissolution of bond between the particles, was established and implemented into a commercial distinct element code. Then, a series of direct shear tests with different connectivity rates and normal stresses under various degree of environmental degradation was conducted in DEM. The results imply that there is a similar tendency of shear stress-displacement curves obtained from intermittent jointed rock mass samples with varying degree of environmental degradation. And with the increasing of environmental degradation degree, the main failure mode of intermittent jointed rock mass changes from tensile crack to shear crack. In addition, the initiation stress, the cohesion and internal friction angle of non-penetrating jointed rock mass are reduced with the increasing of environmental degradation degree.

Key words: environmental degradation, intermittent jointed rock mass, direct shear test, DEM simulation