煤矿为了高产高效,采区巷道普遍采取大断面矩形形状、且沿煤层布置。由于煤层相对于上覆岩层强度较弱,矿压显现明显,煤帮常常出现较大范围的破裂、破坏现象,严重威胁巷道稳定和安全生产。采用高强锚杆(索)加固技术可以维护巷道的稳定,但锚杆长度、直径、间排距等参数主要依靠经验确定,缺乏依据理论的计算方法。本文针对水平层状岩层、矩形煤巷,基于岩层控制关键层理论和弹性地基梁模型,获得岩梁变形及应力解析表达式,以确定煤巷侧帮的压力及破裂范围;进而根据岩土工程稳定原理,确定维护煤帮稳定所需要的锚固力,为锚杆直径及间排距的确定提供理论依据。最后,通过算例进行了煤巷侧帮压力及锚杆参数的计算,其结果符合工程实际。
For high production and efficiency, roadways at mining area are generally arranged along coal seams with large rectangular section. Due to weaker strength of coal seam compared with the overlying strata, obvious mine pressure and large scale of rupture in sidewalls often appear, which have always been great threats to coal roadways stability and production safety. Currently, being an important reinforcement technique, the high-strength anchor(cable) supporting system has been widely used to maintain coal roadway stability, but supporting parameters, such as anchor length, diameter, and anchor arrangement are mainly determined empirically, not dependent on theoretical calculation. Considering rectangular coal roadways and overlain horizontally layered rock and based on the key strata theory in ground control and the elastic foundation beam model, this paper has firstly obtained the analytical expression of stress and the deformation of rock beam, to determine the pressure loading on sidewalls as well as the rupture range. On the basis of this, according to stability principle of geotechnical engineering, the anchoring force required for maintaining sidewall stability has been further studied, which can provide a theoretical basis for determining supporting parameters. Finally, through an example, the pressure loading on sidewalls and the bolting parameters have been calculated, and the result is in goodagreement with the engineering practice.