Geomechanics model test research on large deformation control mechanism of roadway disturbed by strong dynamic pressure

Abstract

Comprehensive mechanized top-coal caving mining is one of the efficient mining methods in coal mines. However, the goaf formed by comprehensive mechanized top-coal caving mining is high, and the goaf roof collapse will cause strong dynamic pressure disturbance, especially the collapse of thick hard roof. Strong dynamic pressure disturbance has an influence on the stability of the roadway, which can lead to large deformation. In order to solve the above problem, a comprehensive pressure releasing and constant resistance energy absorbing control method is proposed. Comprehensive pressure releasing can change the roadway roof structure and cut off the stress transfer between goaf and roadway, which can improve the stress environment of the roadway. The constant resistance energy absorbing (CREA) anchor cable can absorb the energy of surrounding rock deformation and resist the impact load of gangue collapse, so as to ensure the stability of roadway disturbed by strong dynamic pressure. A three-dimensional geomechanics model test is carried out, based on the roadway disturbed by strong dynamic pressure of the extra-large coal mine in western China, to verify the control effect of the new control method. The stress and displacement evolution laws of the roadway with traditional control method and new control method are analyzed. The pressure releasing and energy absorbing control mechanism of the new control method is clarified. The geomechanics model test results show that the new control method can increase the range of low stress zone by 150% and reduce the average stress and the displacement by 34.7% and 67.8% respectively, compared with the traditional control method. The filed application results show that the new control method can reduce the roadway surrounding rock displacement by 67.4% compared with the traditional control method. It shows that the new control method can effectively control the displacement of the roadway disturbed by strong dynamic pressure and ensure that the roadway meets the safety requirements. On this basis, the engineering suggestions for large deformation control of this kind of roadway are put forward. The new control method can provide a control idea for the roadway disturbed by strong dynamic pressure.