Characterizing strata deformation over coal pillar system in longwall panels by using subsurface subsidence prediction model

Abstract

The ground control stability problem due to underground large mine openings often associates with large movements and deformations of strata. The situation becomes more complicated when relative subsidence research involves zones above the coal pillar. Continues fractures in strata created by such subsidence progress may become the pathway of fresh air delivery or water migration in the strata aquifer which would cause the problems of underground coal combustion or water resource losing. Hence, knowing the subsurface strata movement characteristics over gob and coal pillar to make any subsidence predictions are desired for mining engineers to estimate any damages happened in the subsurface strata in advance. This paper proposes a prediction model for investigating subsurface strata movements over the pillar. Using the calculated subsidence results, the related strata fraction distributions are characterised. For validation reason, extensometer boreholes are used to identify the subsurface strata caving progress in a long-wall panel. The measurement results agree with the predications derived by the model shows the reliability of the model. Such research efforts can well help to understand the moving behaviour of all strata over the coal pillars and assist mining engineer to efficiently deal with the possible crack pathways over the coal pillar.