School of Energy, Xi'an University of Science and Technology MOE Key Lab of Mining and Disaster Prevention in
China Westerm Coal Mine School of Resources and Safety Engineering, China University of Mining and Technology
(Bejing)

针对现有巷道冒顶机理在解释回采巷道冒顶机理时适用性不强的问题,以保德矿81305工作面运输巷为工程背景,利用理论分析,数值模拟及现场试验等方法,研究了回采巷道围岩蝶叶形塑性区形成机制和回采巷道蝶叶形塑性区演化规律,并揭示了回采巷道蝶叶形冒顶机理。研究发现,均质岩体圆形巷道塑性区蝶形边界的4个蝶叶会因蝶叶发生退化消失、偏转及扩展而形成蝶叶形塑性区,蝶叶形塑性区蝶叶尺寸主要受到侧压系数、围岩黏聚力、内摩擦角及巷道半径的影响。当蝶叶形塑性区蝶叶位于顶板时,蝶叶内发生塑性破坏的岩层会产生强烈变形,当锚索延伸量无法适应顶板的大变形时,便会出现因锚索被拉断而导致支护失效,使塑性区发生恶性扩展,最终导致冒顶事故的发生。基于回采巷道蝶叶形冒顶机理,提出了可接长锚杆与锚索协调支护技术和可接长锚杆与普通锚杆协调支护技术,该技术在81305工作面运输巷的工业试验,使该巷道在工作面回采期间,锚索破断率由原来64.5%降至12.5%,防止冒顶事故的发生。

According to the stress environment and surrounding rock condition complicated in the mining gateway, when the roof falling mechanism of the available gateway was not suitable applied to explain the roof falling mechanism of the mining gateway, based on the conveying gateway of No.81305 coal mining face in Baode Mine as the engineering background, the theoretical analysis, numerical simulation and site test and other method were applied to study the formation mechanism of th e butterfly leaf shaped plastic zone in the surrounding rock of the mining gateway and the evolution law of the butterfly leaf shaped plastic zone in the mining gateway. Based on the circumstances, the paper revealed the butterfly leaf shaped roof falling mechanism of the mining gateway. The study showed that due to the butterfly leaf, the four butterfly leaf at the butterfly leaf shaped boundary of the plastic zone in the round type mining gateway with homogenous rocks would cause the degradation an d disappearance, deflection and expansion and then would form the butterfly leaf shaped plastic zone. The butterfly leaf size in the butterfly leaf shaped plastic zone we re mainly affected by the side pressure coefficient, the cohesion force of the surrounding rock, internal friction angle and the radius of the gateway. When the butterfly | eaf of the butterfly leaf shaped plastic zone was located above the roof, the plastic failure strata within the butterfly leaf would cause serious deformation. When the ext ension value of the anchor could not suit the large deformation of the roof, the anchor cable would be broken and thus the support failure occurred, the plastic zone Wo uld cause a serious extension and the roof falling accident would be occurred. Based on the butterfly leaf shaped roof falling mechanism of the mining gateway, a bolt e xtended length and anchor coordinated support technology as well as the extended length bolt and conventional bolt coordinated support technology were provided and the technology was applied to the industrial trial of the conveying gateway in No. 81305 coal mining face. During the mining period of the coal mining face, the broken r ate of the anchor was reduced from 64.5% to 12.5% and the roof falling accident occurred was precluded.