Numerical assessment of the influence of former mining activities and plasticity of rock mass on deformations of terrain surface

This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain. The assessment of deformation changes was carried out with the use of FLAC3D program based on the finite difference method. Numerical calculations were carried out for the example of actual mining operations in seams 703/1-2 and 707/2 of “Marcel” Coal Mine. Taking into account the influence of the model’s plastic features and the so-called activation of a higher occurring seam in conducted simulations enabled obtaining a very good description of the measured subsidence. Based on the results one may state that numerical model can be used to assess the influence of former mining activities and the direction of conducted exploitation on deformations of the mining terrain. These factors are not recognized by geometric-integral theories commonly used for predicting the influence of mining operations on the surface. The results presented in this paper confirm that the applied method of simulating the phenomenon of reactivation of post-mining goafs is correct.