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深井大断面沿空留巷常见严重底鼓问题,为更好揭示底鼓机理,利用自行研制的两向四面加载试验装置,结合顾桥矿1115(1)工作面轨道顺槽工程地质条件,采用相似材料模拟方法研究了深井大断面沿空留巷底板在掘进、一次采动、留巷和二次采动影响期间裂隙动态演化规律,并基于分形几何理论定量分析了分形维数变化规律及其与底鼓量的关系。研究结果表明,底板裂隙随着回采逐步发育、扩展、贯通,以剪切破坏的中高角度裂隙分布为主;底板裂隙分形维数逐渐增加,在顶板来压和留巷期间均有明显的升维现象;由于留巷上部基本顶的“回弹”现象,第二个工作面上覆岩层作用于煤体的载荷较小,导致在第二个工作面回采前期,底板裂隙分形维数增量较小;底鼓量和分形维数呈非线性正相关关系。通过对比现场实测底鼓量和试验底鼓量,发现二者能够较好吻合,验证模型试验结果的真实可靠。
In order to better reveal the bottom drum mechanism, a self-developed two-way and four-side loading test device was used in combination with the engineering geological conditions of the 1115 (1) Similar material simulation method was used to study the dynamic evolution of fractures in the deep gob-side entry retaining floor during tunneling, primary mining, retaining gateway and secondary mining. Based on the fractal geometry theory, the variation regularity of fractal dimension Relationship with the amount of bottom drum. The results show that the fractures of bottom floor gradually develop, expand and penetrate, and the fracture distribution at middle and high angles is mainly dominated by the mining. The fracture fractal dimension of bottom slab gradually increases. Phenomenon; Due to the “rebound” phenomenon of the top of the upper part of the retaining laneway, the load of the overlying rock layer acting on the coal body in the second working face is relatively small, resulting in the increase of the fracture fractal dimension of the bottom face in the early stage of the second face mining The amount of bottom drum and fractal dimension showed a nonlinear positive correlation. By comparing the measured drum volume with the measured drum volume, we found that the two are in good agreement with each other to verify the authenticity of the model test results.