A Numerical Approach Considering Mining-Induced Fracture Weakening and Goaf Compaction on Surface Subsidence

The precise prediction of surface subsidence under mining influence is significant for ecological environment and personal safety. This paper presents a numerical approach for surface subsidence analysis based on a case study conducted at Gucheng mine, China. Considering the rock mechanical characteristics of fractured zone and caved zone, the tension-weakening model and the double-yield model with back-analyzed properties are implemented into FLAC3D to simulate the mining-induced fracture weakening and the goaf compaction process, respectively. The reasonable goaf material and the relationship between the intensity of fractures and the residual stiffness of rock mass are built in the numerical model. An analysis of tension-weakening and double-yield models is carried out and the simulated results are compared to strain-softening model. It is shown that the combination of tension-weakening and double-yield models provides a more realistic simulation of surface subsidence than strain-softening model. The numerical approach can be utilized for control and prediction of surface subsidence under similar geotechnical conditions.