Stepped shearing-induced failure mechanism and cracks propagation of overlying thin bedrocks under coal seams mining in shallow deep

XUE Dong-jie, ZHOU Hong-wei，REN Wei-guang，ZHANG Bo-fu，LIU Ya-qun，ZHAO Yu-feng

Abstract

To study on the cracks propagation of overlying thin bedrocks in shallow deep coal seams mining is useful for understanding the stepped shearing-induced failure mechanism of overlying thin bedrocks. Based on the geology in Daliuta coal mine, the physical model was designed for mining 1-2upcoal seam first, then 1-2 coal seam below. The analysis on the evolution of mining-induced cracks was made in the study. Broken-induced volumetric expansion is obvious in mining the upper coal, as well as surface subsidence increases in mining the lower coal. According to periodic weighting, there are two linear stages of fractal dimension in mining the upper coal. After mining the lower coal, the fractal dimension will tend to be a stable value. Furthermore the percolate probability shows a linear relationship with the advancing distance, and two critical states have been obtained. Finally the study on the formation mechanism of stepped shearing-induced failure is made. The rock seam spring effect and tension-induced collapse are proposed,and the main reasons about stepped shearing-induced failure by tension are provided.

引用格式：

薛东杰, 周宏伟, 任伟光, 张博夫, 刘亚群, 赵宇峰. 浅埋深薄基岩煤层组开采采动裂隙演化及台阶式切落形成机制[J]. 煤炭学报, 2015, 40(08): 1746-1752. (XUE Dong-jie, ZHOU Hong-wei，REN Wei-guang，ZHANG Bo-fu，LIU Ya-qun，ZHAO Yu-feng. Stepped shearing-induced failure mechanism and cracks propagation of overlying thin bedrocks under coal seams mining in shallow deep[J]. Journal of China Coal Society, 2015, 40(08): 1746-1752. (in Chinese))

DOI：10.13225/j.cnki.jccs.2014.1168

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