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.
Highlights
An appropriate evaluation of shear behavior of rock joints is vital, for instance, when analyzing the stability of rock slopes, designing excavations in jointed rock, and designing rocksocked piles [1]
The influence of engineering disturbance on rock joints was quantified in the form of stress and the stress model was established
After a series of theoretical study, experimental investigation, and numerical simulation, some conclusions can be drawn as follows: (1) The stress state related to different kinds of disturbance was analyzed
Summary
An appropriate evaluation of shear behavior of rock joints is vital, for instance, when analyzing the stability of rock slopes, designing excavations in jointed rock, and designing rocksocked piles [1]. A considerable amount of work has been conducted to describe the shear behavior of rock joints [2,3,4,5,6,7,8]. Many studies have indicated that the large-scale engineering work destroyed the original stress balance of rock joints and influenced their shear behavior. Studying the failure process and degradation characteristics of rock joints under dynamic loading is critical for analyzing the failure mechanism of unstable work under dynamic disturbance. The methods used to judge the block stability and determine the key blocks show that block stability is dominated by shear behavior of rock joints. The strength deterioration of rock joints inevitably induced the emergence of key blocks. It is of great importance to judge the block stability and establish a method to determine the key blocks under engineering disturbance
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