厚煤层快速回采切顶卸压无煤柱自成巷工程试验

基于切顶卸压自动成巷技术原理，分析了沿空切顶巷道顶板结构演化过程，得出厚煤层快速回采切顶成巷围岩应力、位移传递机制，形成了人为主动构建“基本顶上位岩层-采空区碎胀矸石-巷道切顶短臂梁”围岩稳定结构的控制思路。提出厚煤层快速回采沿空切顶巷道围岩协同控制体系，以“恒阻大变形锚索+墩式单元支架”控制顶板，以“滑移式让位护帮结构+自移式动压防冲结构+波浪式多阻护帮锚杆”控制帮部，形成了应对顶板结构位态、碎石运动状态变化的针对性控制技术。以柠条塔煤矿S1201胶运顺槽为工程背景，完成了厚煤层快速回采条件下切顶卸压无煤柱自成巷现场工业性试验。研究表明，采高增大、采速加快后，基本顶上位岩层易引发少量不宜强制控制的回转变形，支护结构可控让位是构建围岩稳定结构的有效途径之一；巷内压力与采空区矸石运动状态密切相关，增强预裂效果有利于减少动压冲击；成巷过程中巷道顶压首先达到恒阻状态，而后位移趋于稳定，最后形成围岩稳定结构。所设计的配套支护结构可有效协同围岩运动，留巷效果良好。

Engineering experimentation of gob-side entry retaining formed by roof cutting and pressure release in a thick-seam fast-extracted mining face

In the study, evolution laws of the roof structure were first investigated based on the principle of gob-side entry retaining formed by roof cutting and pressure release. Subsequently, stress and displacement transfer mechanisms of the surrounding rocks around a thick-seam fast-extracted mining face were discussed. Correspondingly, an active stability control approach for the entry surroundings was proposed by building a rock-steady structure using the upper strata of the main roof, bulking gangues at the gob and cutting cantilever of the entry roof. According to the deformation characteristics of the entry surroundings, we designed a series of cooperative supports with characteristics of constant resistance and pressure release. Particularly, the roof was supported by the constant resistance and large deformation anchor cable and pier-type unit. The gangue rib was stabilized by the sliding-type side wall prevention structure, self-advancing dynamic pressure bearing device and side wall prevention bolt with multi-resistances. Finally, industrial field tests were conducted in S1201 haulage entry of Ningtiaota coal mine for the first time. The results indicated that with increasing mining height and accelerating mining speed, a small amount of rotational deformation occurred inevitably owing to the movement of the main roof. Moreover, this deformation was not suitable to be supported compulsorily, and should be better coordinated by building a rock-steady structure artificially. The motion state of the gangues was closely related to the roof pressure, and thus an enhanced presplitting helped to reduce impacts of the dynamic mining pressure. Field monitoring results showed that the roof pressure first reached the constant resistance, and then the displacement tended to be stable. Finally, the rock-steady structure of the entry surroundings was formed. It was verified that the designed support structures could effectively coordinate with the movement of the surrounding rocks, and the indexes of the retained entry met requirements of the next mining panel.