Numerical simulation of open pit slope cumulative failure and stability under repeated blasting

To study the stability and cumulative failure of Beskuduk Open-pit Mine slope under repeated blasting vibration, the 3DEC software is adopted to deeply investigate it. The slope numerical model is set up according to the slope structure characteristic. The measured blasting seismic wave of the mine is used as the vibration input of the model, and the variation laws of the slope horizontal displacement, stability coefficient and failure process with the number of blasting vibrations are simulated and analyzed. The field displacement monitoring results are adopted to validate this numerical model. The results show that the failure process of the slope under repeated blasting vibration can be divided into three stages: the initial failure stage, the crack development stage and the instability failure stage; with the increase of the number of blasting, the cumulative displacement of each bench continuously increases, and shows a slow-fast-slow variation law. The stability coefficient of the slope gradually decreases, and shows a slow-fast variation law. When the slope is subjected to 320 repeated blasting vibrations, the stability coefficient of the slope drops to 1, reaching the critical failure state. The influence law of the vibration acceleration amplitude and layer thickness on the dynamic response of the slope is studied with the parameter sensitivity analysis. It was found that with the increase of the number of vibrations, the cumulative displacement of each bench continuously increases. When the peak acceleration of the seismic wave is 0.1g, 0.2g and 0.4g respectively, the number of vibrations required for the slope stability coefficient to drop from the initial 4.7 to 1 is 290, 180 and 24 respectively. That is, the larger the vibration load amplitude, the smaller the number of vibrations required for slope instability failure. When the layer thickness is 3 m and 8 m respectively, the slope stability coefficient decreases from the initial 3.82 and 6.58 to 1 after 162 and 467 vibrations respectively, and the slope becomes unstable. That is, the larger the layer thickness is, the stronger the initial stability of the slope is, and the more vibrations are required for failure.