Abstract

The water-blocking action of the clay Cenozoic overburden layer 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.

中文翻译：

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基岩厚度对薄基岩煤层开采上覆土层变形破坏的影响研究

摘要

粘土新生界覆盖层的阻水作用是影响薄基岩煤层开采安全性的重要因素。薄基岩厚度的变化对上覆土层的变形和破坏具有重要影响。在这项工作中，使用相似性模拟实验，并选择了破坏高度和土层裂缝密度两个指标，以分析薄基岩厚度对覆土层变形和破坏的影响。实验结果表明，随着基岩厚度的减小，土层的破坏高度增大。基岩厚度大于30 m（开采厚度为6 m）时，破坏高度的变化较小，而基岩厚度小于30 m时，破坏高度的变化较小，随着基岩厚度的减小，土层的破坏高度迅速增加。薄基岩厚度减小对上覆土层变形和破坏的主要影响导致剪切/拉伸裂缝的增加。当基岩厚度为70 m时，剪切/拉伸裂纹密度为0.04条/ m，而当基岩厚度减小至20 m时，剪切/拉伸裂纹密度为0.14条/ m。