Study on the Influence of Bedrock Thickness on Deformation and Failure of Overlying Soil Layer in Thin Bedrock Coal Seam Mining
G. Wu, H. Bai, L. Wu, S. He
1China University of Mining & Technology, Xuzhou, Jiangsu, China
2China University of Mining and Technology, Xuzhou, Jiangsu, China
Keywords: налегающий глиняный слой, имитационное моделирование, плотность трещин, плотик малой мощности, Clay overburden, similarity simulation, crack density, thin bedrock
Abstract
The water-blocking action of the clay Cenozoic overburdenlayer is an important factor that affects safety of thin bedrock coal seam mining. The change of thin bedrock thickness has an important influence on the deformation and failure of overlying soil layer. In this work, similarity simulation experiment is used and two indexes of failure height and crack density in soil layer are selected to analyze the influence of thin bedrock thickness on the deformation and failure of overlying soil layer. The experiment results show that the failure height of soil layer increases with the decrease of the bedrock thickness. The change of failure height is small when the bedrock thickness is greater than 30 m (mining thickness is 6 m), while when the bedrock thickness is less than 30 m, the failure height of soil layer increases rapidly with the decrease of the bedrock thickness. The main effect of the decrease of the thin bedrock thickness on the deformation and failure of the overlying soil layer results in the increase of shear/tensile cracks. The shear/tension crack density is 0.04 strip/m when the bedrock thickness is 70 m, while the shear/tension crack density increases to 0.14 strip/m when the bedrock thickness reduced to 20 m.
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