Characteristics of surrounding rock cracking induced by excavation on the underground mineral processing plant

Aiming at the damage and fracture problems of surrounding rock mass during the excavation of Zhangjiawan underground mineral processing plant, the evolution rules of cracking initiation and propagation in rock mass are simulated after a RFPA^2D numerical analysis model established.And the stress effect induced by unloading condition and its influence on the surrounding rock cracking are explored.The scale of rock mass cracking caused by transient unloading is studied based on the criterion of acoustic emission (AE).The results show that the side wall of chamber first appeared initiation failure, and gradually develop along the vertical direction.The development direction of macro cracks is parallel to the maximum principal stress.And the homogeneity has a great influence on the crack extension and the higher the homogeneity, the more concentrated the stress distribution, the more brittle the fracture of the surrounding rock is.