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煤层开采过程中,开采工作面围岩一定范围内的岩体会产生卸荷裂缝或新裂隙,其中有一部分裂缝和裂隙存在张开的经历。由于张开的裂隙和缝隙内没有力的传递介质,在这些裂缝、裂隙附近区域的应力会从因重力引起的应力大值降低到一个很小的值,但不一定会达到应力为0值。裂缝、裂隙附近区域的应力由于之后的应力重分布可以发生调整而振荡,裂缝、裂隙相应地可以闭合,甚至可以承受很大的剪应力。基于一部分采动张开裂隙附近区域的应力大值曾经历过大幅度卸载到一个很小值这一动态过程,提出了一种识别采动裂隙带发育的动态应力追踪方法。以宁夏石嘴山矿区三号煤层为工程背景,利用离散元UDEC软件包计算确定煤层开采过程中覆岩内部不同开采阶段的应力分布。借助于后处理软件Tech Plot,利用提出的动态应力追踪方法,识别该矿采动裂隙带的范围和高度;研究结果表明,所提出的动态应力追逐方法具有可行性和很好的适用性。
During the process of coal seam mining, the rock mass within a certain range of the mining face of the working face will have unloading or new cracks, among which some cracks and crevices exist. Due to the open crack and the transmission medium with no force in the gap, the stress in the vicinity of the crack will be reduced to a very small value due to the gravity-induced stress, but the stress will not necessarily reach zero. Cracks, cracks in the area near the stress due to the subsequent stress redistribution can be adjusted and oscillation, cracks, cracks can be closed accordingly, and even can withstand large shear stress. Based on the fact that a large part of the stress in the vicinity of mining open crack has undergone a dynamic process of large unloading to a very small value, a dynamic stress tracking method is proposed to identify the development of mining fractured zone. Taking the No.3 seam in Shizuishan mining area of Ningxia as an example, the stress distribution in different mining stages in the overburden strata during the process of coal seam mining was determined by using the discrete element UDEC software package. Using the post-processing software Tech Plot, the proposed dynamic stress tracking method is used to identify the range and height of the mining fracture zone. The results show that the proposed dynamic stress chase method is feasible and well applicable.