Sliding and falling process of rock block in jointed roof under dynamic disturbance

Abstract

The roof fall disaster in underground mine always threatens the safety of workers and equipment. Under the disturbance of blasting or earthquakes, it is easy to induce a sliding-type instability caving for a jointed roof rock mass. Experimental research on roof trapezoid key block is performed to study the sliding and instability process due to dynamic disturbance. A disturbed sliding test is conducted under the conditions of 5, 8, 10, 15, and 20 kN static lateral clamping load with different disturbance energies. The evolution law of sliding displacement and deformation during the disturbed sliding process of a key block is analyzed. Meanwhile, the critical disturbance energy of key block instability under different clamping load conditions is obtained, which exhibits an exponential relationship. Moreover, a theoretical calculation method of the disturbed sliding distance of key blocks under different disturbance energies and clamping load conditions is proposed based on the law of conservation of energy. Besides, the critical instability sliding distance can also be obtained from the proposed method. The calculated results agree well with the experimental results, which can provide theoretical guidance for the real-time risk assessment of roof rock blocks under the condition of displacement monitoring.