Numerical modelling of multistage caving processes: insights from multi-seam longwall mining-induced subsidence

Evaluating the induced subsidence is a critical step in multi-seam longwall mining. Numerical modelling can be a cost-effective approach to this problem. Numerical evaluation of longwall mining-induced subsidence is much more complicated when more than one seam is to be extracted. Only a few research works have dealt with this problem. This paper discusses the essential requirements of a robust numerical modelling approach to simulation of multi-seam longwall mining-induced subsidence. In light of these requirements, the previous works on this topic are critically reviewed. A simple yet robust FEM-based modelling approach is also proposed that is capable of simulating caving process, rock mass deterioration and subsidence around multi-seam excavations. The effectiveness of this approach in comparison with two other conventional FEM approaches is demonstrated through numerical examples of two different multi-seam mining configurations. Results show that the proposed numerical modelling approach is the only robust method, which is capable of simulating multi-seam subsidence in both demonstrated cases.