Study on loading and failure instability mechanism of “support-surrounding rock” system in large dip angle and large mining height working face

The stability of “support-surrounding rock” system in a large dip angle and large mining height working face is the key to safe mining of the working face. A three-dimensional large-scale simulation experiment platform and a supporting hydraulic support were developed by combining field measurement, theoretical analysis, and three-dimensional physical simulation experiments. The non-equilibrium instability and dynamic response characteristics of “support-surrounding rock” under impact load were analyzed, and the mechanical behavior mechanism of support under large dip roof load was revealed. The results show that due to the increase in mining height and the effect of gravity-inclination angle, the roof load of the working face with a large dip angle and large mining height is transmitted to the base through the non-equilibrium of the top beam of the support. The dynamic load impact leads to the forward deflection of the top beam of the support and the non-equilibrium regional fracture of the roof. The loading stress is mainly concentrated on the left side of the inclined front end of the top beam. The left deflection of the front end of the support base is greater than the right side, and the rotation instability subsidence of the support occurs. The rotation amplitude of the support increases with the decrease in the normal load of the roof, the increase in the tangential load of the roof, and the increase in the eccentric load of the roof. The research results provide guidance for the stability control of the “support-surrounding rock” system.