Mine-scale numerical modelling of longwall operations

Elastic three dimensional Boundary Element (BE) codes are commonly used in the coal industry to model the induced stresses and rock mass response to longwall mining. While these models are often easy to build and quick to run, it is questionable whether these elastic models are capable of accurately simulating the highly non-linear rock mass response observed in longwall operations, in particular the complex caving and goaf behaviour of the overlying strata and resulting surface subsidence. This study presents a comparison between modelling results obtained from the finite difference (FD) code FLAC3D and elastic BE code Map3D for a generic longwall extraction sequence. These models are compared with regard to the extent of surface subsidence and associated stability of pillars.