Research on the control of overburden deformation by filling ratio of cementing filling method with continuous mining and continuous backfilling

Underground resource exploitation has seriously damaged the surface ecological environment and underground water system. As an effective control measure, the filling mining process has greatly reduced the surface subsidence. As a branch of the filling mining process, the continuous mining and continuous backfilling (CMCB) method solves the contradiction of mining and filling in this process. The control index of filling ratio of even number lane (FRE) was presented to investigate the technical advantages of the CMCB method. The numerical analysis model was used to investigate the laws such as deformation characteristics of the surrounding rock, stress distribution, and plastic area distribution characteristics of backfill under four typical cases. As a consequence, the FRE effect law on overburden deformation and the roof control function of the backfill was disclosed, and overburden rock deformation control solutions were provided. According to the results, the overburden deformation varies dramatically when the FRE decreases, and it rises greatly when the even-numbered lane backfill (ELB) is not contacted with the roof. The contacting condition and filling condition of the odd numbered lane backfill (OLB) are connected to the distribution of stress and plastic zone. The backfill transmits the rock beam load by building a composite support system with the roof and floor rock layers, and it accomplishes the backfill's roof control function by combining the primary and secondary load-bearing and synergistic load-bearing connections between the backfills. Measures such as differential FRE, differential strength, non-uniformity of filling lane, and synergistic bearing of temporary support and backfill may help to decrease deformations and internal cracks in the surrounding rock. This measure has been successfully implemented in the field, serving as an experience for the application of the CMCB method.