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为了探究坚硬顶板急倾斜特厚煤层在未强制放顶条件下,采用水平分段放顶煤方式开采时围岩的运动和裂隙发育规律,采用相似材料模拟的方法进行了研究。通过低强度正交配比试验,确定煤层配比为水泥∶砂子∶水∶活性炭∶煤=6∶6∶7∶1.1∶79.9,所制煤层密度为0.913g/cm3,单轴抗压强度为0.076 MPa,符合相似理论的要求和现场实际情况。相似材料模拟试验结果表明:工作面开采2~3个水平后上覆岩层才会发生大面积的整体垮落;在埋深较浅的水平,上覆岩层垮落前形成整体结构协调运动,在埋藏较深的水平,顶板在各个水平发生较小程度的垮落,相邻水平之间能够形成铰接结构;进入深部开采水平后,各水平开采后顶板随之发生破坏并垮落;顶板离层及裂隙发育规律与顶板运移和垮落规律有较强的一致性;开采水平底板煤层接近岩石底板一侧的应力卸压程度要高于接近岩石顶板的一侧,开采层下部煤层显著卸压深度约为15 m。
In order to explore the law of the movement and fissures of the surrounding rock in horizontal section caving mining under the conditions of not top caving, the method of simulating with similar materials was studied. Through low intensity orthogonal proportioning test, the ratio of coal seam is determined as cement: sand: water: activated carbon: coal = 6: 6: 7:1.1:79.9, the density of the coal seams is 0.913g / cm3 and the uniaxial compressive strength is 0.076 MPa, in line with the requirements of similar theory and the actual situation on site. The simulation results of similar materials show that large-area collapse will occur in the overlying strata only when the working face is mined from 2 to 3 levels. At the shallow depth, the overlying strata will form a coordinated whole-body movement before they collapse. Buried at a deeper level, the roof collapses to a lesser extent at all levels, and hinges can be formed between adjacent levels. After entering the deep mining level, the roof subsequently breaks down and collapses after each level of mining. The roof delamination And the law of fracture development is in good agreement with the roof migration and caving law. The stress relief pressure near the rock bottom of the mining floor coal seam is higher than that close to the rock roof, and significant pressure relief The depth is about 15 m.