复采工作面过冒顶区顶板断裂特征及控制研究

Characteristics and control of roof fracture in caving zone for residual coal mining face

针对复采工作面过冒顶区时工作面易发生煤壁滑帮、端面冒漏以及顶板来压强度大等特点,以晋煤集团圣华煤业3101复采工作面为工程背景,运用相似模拟对复采工作面过冒顶区时顶板破断特征、支承压力分布特征以及支架受力状态进行研究,依据相似模拟结果建立复采采场力学模型,推导液压支架支护强度的计算公式,提出复采工作面过冒顶区时的围岩控制技术。研究结果表明:(1)工作面过冒顶区时采场顶板易形成大厚度、长跨距的超前大断裂;(2)冒顶区弱化了顶板岩梁的应力传递,加剧了支承压力的荷重集度;(3)液压支架受顶板超前大断裂的影响,支架工作阻力在通过冒顶区前呈突变性增加,模拟结果支架支护阻力最大值为16 200 k N,理论计算支架支护阻力为16 110.5 k N;(4)复采工作面在通过冒顶区前必须对冒顶区进行注浆充填,同时给出支架工作阻力随充填体强度变化的关系式,为复采采场顶板控制提供理论依据。

The residual coal mining face #3101 at Shenghua Coal Industry of Jincheng Anthracite Mining Group was studied to investigate the roof fracture characteristics,surrounding rock stress distribution and support stress state in the caving zone for residual coal mining face using the analog simulation considering the coal face sloughing,tip-to-face flaking and larger roof weighting strength features. On the basis of the simulation results,a mechanical model of residual coal mining field was established,a formula calculating the hydraulic support strength was derived,and further surrounding rock control technology in the caving zone for residual coal mining face was proposed. The roof of residual coal mining field was found to form easily thicker and long-span advanced fractures. The caving zone weakened the stress transfer of roof strata and aggravated the loading intensity of the support pressure. The working resistance of the hydraulic support suddenly increased due to the effect of advanced large fracture,its maximum value from numerical simulation is 16 200 k N,and the theoretically calculated value is 16 110.5 k N. The residual coal mining face must be grouted before passing through the caving zone. The relationship between the support working resistance and filling body strength was determined.