Dynamic Shear Strength of Rock Joints and Its Influence on Key Blocks

Abstract

Shear strength deterioration of rock joints and its induced instability of key blocks subjected to dynamic disturbance constitute the mechanism of many geological disasters such as rockburst, landslide, and rockfall. In this study, the influence of dynamic disturbance on rock joints was quantified in the form of stress, of which model was established by quasistatic method. The dynamic shear strength of rock joints was analyzed theoretically following the Coulomb-Navier criterion and further investigated experimentally by split Hopkinson pressure bar (SHPB) tests with impact velocities of 4.850 m/s, 8.722 m/s, 12.784 m/s, and 16.935 m/s. The effect of engineering disturbance on shear strength of rock joints was measured, and a degradation coefficient was used to describe it quantitatively. Considering the degradation of dynamic shear strength of rock joints and its influence on block stability, the method for determining key blocks under dynamic disturbance was given. Implementing this method into the program of Geotechnical Structure and Model Analysis-3D (GeoSMA-3D) developed by the authors’ team, the visualization of key blocks was achieved. From theoretical analysis and experimental investigation, it was figured out that the shear strength of rock joints is degraded under dynamic disturbance. The degradation of friction angle becomes more sensitive than that of cohesion. Additionally, numerical results show that the number of key blocks was increased with the increasing impact velocities.

Estimation of Shear Strength Parameters Considering Joint Roughness: A Stability Case Analysis of Bedding Rock Slopes in an Open-Pit Mine

“…Figure 14 shows the external morphology of the slope, but it does not reveal the key blocks inside it. Therefore, it is necessary to calculate the data of the key blocks to conduct a thorough assessment of the slope's stability before and after the parameter correction [37]. Tables 7 and 8 present the calculated data, demonstrating that the number of key blocks was reduced from 8 to 6.…”

Drill Bit Stick-Slip Vibration Experiment Research and Analysis of Influencing Factors

“…When a rock fails, it is related not only to the shear stress on the surface but also to the magnitude of the normal stress on the surface, according to the Coulomb-Navier criterion [28]. The damage to the rock is produced along the most unfavorable side of the combination of shear stress and normal stress.…”