Ground Deformation And Subsidence Mechanism Of Old Mining Area

With the decrease of land resources, to make the most of the old mining areas, and ensure the safety of important traffic engineering and residential buildings found on the mining areas, the research of subsidence mechanism and surface deformation of mining areas is of important social economic significance for developing a suitable and rational treatment technology.Based on three-dimensional finite difference method, the numerical model is discussed according to the actual conditions of old mining areas. The deformation features and law of ground surface were further investigated to reveal subsidence mechanism of mining areas. The preliminary conclusions are drawn as the following:1) When the coal seam was excavated one by one, the smaller stress was observed in the upper strata area along the dip direction, but the larger value in the bottom area. And the stress deviation decreased with the excavation process.2) The ground subsidence and curvature changed slightly along the strata strike, on the other hand, changed greatly along the dip direction. The subsidence distributed symmetrically around the center of the max settlement as center.3) Damage of overlying rock mass mainly occurred at the direction of strike. The overlaying rock masses were collapsed after the Coal 1 was mined, but the overlaying rock masses were ruptured when the other coal was mined.4) The computed ground subsidence from the numerical simulation was coincident with that from the probability integration method and the measured value of surface subsidence over years.These results will contribute to the surface subsidence control, and provide a theoretical basis for the foundation treatment techniques of old mining areas.