Abstract:

After reservoir impoundment, the frequency of medium-low intensity earthquakes in and around the reservoir area increases, and the landslide-prone zone expands. To reveal the influence of dynamic load on the mechanical properties of slope rock mass, typical limestone in the Baihetan Reservoir area was taken as the research object, and cyclic shear tests with different dynamic load amplitude ratios were carried out to analyze the degradation laws and mechanisms of joint mechanical properties under saturated state. The results show that: 1) Under cyclic dynamic shear with different amplitudes, the peak shear strength, residual shear strength and pre-peak shear stiffness of joints all show linear degradation characteristics. 2) Considering the influence of joint roughness coefficient on shear strength, the JRC-JCS model (joint roughness coefficient-joint wall compressive strength) is introduced to verify the test data, and the model is modified based on the degradation effect of cyclic shear on joint wall strength. After modification, the error between the calculated value and the test value is reduced to less than 5%. 3) The greater the cyclic disturbance amplitude, the more significant the damage to rock and joint surface. The continuous degradation of bank slope structural planes and rock mass damage accumulation in the reservoir area need to be focused on. The research results can provide a reference for analyzing the mechanical properties of reservoir slopes under the action of medium-low intensity induced earthquakes.

Key words: rock mechanics, cyclic shear, deterioration effects, joints, damage characterization