宽断面预留墩柱沿空留巷墩柱支护阻力计算研究

Analysis of supporting resistance of reserved pier column for gob-side entry retaining in wide roadway

针对常规沿空留巷技术在工作面回采速度和采空区作业危险性方面存在的局限性,提出了一种新型沿空留巷技术——宽断面预留墩柱沿空留巷技术,该技术的实施步骤为:首先掘进一条宽断面巷道,随后在巷道断面中心安设一排墩柱,墩柱的一侧为本工作面的运输巷,另一侧作为下一工作面的轨道巷,墩柱作为巷旁支护体使下一工作面的轨道巷保留下来以供使用。结果表明:在掘巷时设立墩柱能够维持宽断面巷道围岩的稳定,同时避免了传统沿空留巷在工作面后方作业,安全性得到了较大提高。在巷道掘进阶段,采用二次成巷技术和锚杆-墩柱联合支护技术可保证巷道的稳定;在留巷阶段,高强度的墩柱对沿空留巷顶板的切断和支撑有较好的控制效果,当墩柱间距为1.5 m时,切顶所需墩柱阻力为21.53 MPa,小于墩柱抗压强度(42 MPa),墩柱承载力满足沿空留巷要求,顶底板相对移近量为652 mm,墩柱压缩量最大值为164 mm,墩柱能起到一定让压作用,同时对顶板有较好的支撑,可以很好地适应沿空留巷顶板活动规律,现场应用效果良好。

Conventional gob-side entry retaining technology has some limitations, such as mining speed restriction and risks of working in the goaf. In this study, we proposed a modified gob-side entry retaining technology named pier column reserving technology in the wide roadway. First, a wide roadway is excavated, and a row of pier columns are established in the middle of the roadway. One side of pier columns is the conveyance roadway of the working face, and the other side is the rail roadway of next working face. Then the rail roadway with the support of pier columns can be retained to use for the next working face. The results show that the pier columns can maintain the stability of surrounding rock during roadway drivage. Meanwhile, the safety is improved greatly by avoiding working behind the working face. During the roadway excavation, the technology of roadway secondary excavation and the bolt-column combined support are used to guarantee the roadway stability. At the stage of gob-side entry retaining, the high strength pier columns have great performance on roof cutting and supporting. When the distance between pillars is 1.5 m, the required pressure of pier column for roof cutting is 21.53 MPa, which is lower than the compression strength of pier columns. The bearing capacity of the pier column meets the requirements of gob-side entry retaining. The relative displacement of the top and bottom plates is 652 mm, and the maximum convergence of pier column is 164 mm. The pier column can play a certain role in relieving pressure and has good support to the roof, which can be well adapted to the roof activity law of gob-side entry retaining.