大采高综采端头悬顶水力切顶控制机理

(1.西安科技大学 能源学院,陕西 西安 710054; 2.西安科技大学西部矿井开采及灾害防治教育部重点实验室,陕西 西安 710054)

矿业工程; 端头顶板; 水压致裂; 定向裂隙; 裂隙演化

Control mechanism of hydraulic roof cutting for end suspended roof of fully-mechanized mining face with large mining height
DENG Guang-zhe1,2,ZHENG Rui1,2,XU Dong1,2

(1.College of Energy Science and Engineering,Xi'an University of Science and Technology,Xi'an 710054,China; 2.Key Laboratory of Western Mine Exploitation and Hazard Prevention,Ministry of Education,Xi'an University of Science and Technology,Xi'an 710054,China)

mining engineering; end roof; hydraulic fracturing; directional fracture; cracks evolution

DOI: 10.13800/j.cnki.xakjdxxb.2019.0207

备注

为解决大采高综采端头顶板难垮问题,以陕北侏罗纪典型煤层条件为背景,结合理论分析、数值模拟与现场试验,对顶板破坏时的人工干预破断裂隙演化与其采动应力耦合作用规律进行研究。通过对顶板割缝损伤弱化模型的研究,揭示水压裂隙控制顶板的破断规律,给出定向割缝的控制参数; 基于此,构建定向裂隙与采动应力耦合模型,分析水压切割定向裂隙控制顶板破断的裂隙演化规律,提出水压致裂切割定向裂隙控制端头顶板破断的技术方案与工艺方法。结果 表明:顶板水压致裂后,顶板破坏类型由拉伸破坏转变为拉剪复合破坏,定向裂隙尖端形成了翼型裂纹与反翼型裂纹,顶板破断角由45°变成56°,煤壁塑性区、片帮深度均减小; 现场试验后,初次来压步距为32 m,周期来压步距为12.2 m.

In order to solve the issue of difficult roof collapse at the end of fully mechanized coal mining with large mining height,taking a typical coal seam in the Jurassic period in northern Shaanxi as the background,the artificial interference of the evolution of broken fracture and the law of coupling action of mining stress during the roof failure were studied by theoretical analysis,numerical simulation and field test.The investigation into the damage weakening model of roof joint revealed that the breaking rule of roof is controlled by hydraulic fracturing crack.Based on this,we gave the control parameters of directional cutting joint.The coupling model of directional fracture and mining stress was built,the fracture evolution law of hydraulic fracturing and cutting directional fissure-controlled roof fracture were analyzed,and the technical scheme and method of controlling end-plate fracture by directional fracture in hydraulic fracturing cutting were put forward.The results show that after roof hydraulic cracking,the failure type of roof is changed from tensile failure to tensile shear composite failure,and the wing crack and reverse wing are formed at the crack tip of directional crack,the broken angle of roof changes from 45° to 56°,and both the plastic zone of coal wall and the depth of roof decrease.After the field test,the initial pressure step distance is 32 m,and the periodic pressure step distance is 12.2 m.