To reveal the mechanical behavior mechanism of collapse and to control risks effectively, the instability extent of the collapse area was established through theoretical mechanics and numerical methods, taking one metal mine as a case study; on this basis, a routine reinforcement program was determined, and the effect of the program was evaluated. The results show the following. (1) Analytical formulas of the critical slip angle and the collapse height of the ore body were derived by the mechanics method, and the rock mechanics parameters were obtained by field coring and physical and mechanical experiments. The slipping line angle increases along with uniform force Q and is inversely proportional to the bending stiffness. Meanwhile, the calculation formula for the maximum subsidence of ore body was deduced. (2) Numerical results can be used to determine the basic form of the collapse area, and a “U-shaped” collapse area formed when a plastic area passed completely through, resulting in the overall destruction. (3) The grouting reinforcement program includes “determining the instability region ⟶ roadway temporary support ⟶ improve the water environment and surrounding rock bearing capacity ⟶ mining planning” which were determined on the basis of prediction. (4) The hierarchical structure of the rock body and filling were improved combined with the Delphi method, and the grouting effect evaluation model was constructed and verified using the improved FD-AHP method; the evaluation value indicating that the grouting reinforcement improved the bearing capacity of ore body and filling body in collapse area. The research results provide systematic reference and technical support for the analysis of stope collapse mechanism, prediction of hidden trouble, and the subsequent mining.
Application of polymer grouting reinforcement technology in the treatment of slope collapse