急倾斜特厚煤层开采相似材料模拟试验研究

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。

Similar material simulation test of steep-inclined extra-thick coal seam

Similar material simulation test has been applied to research the motion of overlying strata and the characteristics of fracture development of steep-inclined extra-thick coal seam mining by hori-zontal section top coal caving. The proportion of coal seam has been chosen as cement∶sand∶water∶activated carbon∶coal=6∶6∶7∶1.1∶79.9 by low strength mechanical test and orthogonal test with the density of 0.913 g/cm3 and uniaxial compressive strength of 0.076 MPa. The result of similar mate-rial simulation test has shown that 1) The overlying strata caving occurs as an integrity only after two or three mining levels have been mined; 2) The overlying strata of shallow mining levels move coordi-nately before caving; 3) In the deep mining level, hinge structure is formed between adjacent mining levels; 4) When the mining activity goes deeper, roof gets completely destroyed and caved after each mining level is mined; 5) The characteristics of abscission layer and fracture development are consis-tent with the motion of overlying strata; the depth of pressure relief is about 15 m.