软岩巷道破坏机理及控制研究

Research on Failure Mechanism and Control of Soft Rock Roadway

针对软岩巷道大变形问题,以贯屯煤矿50213工作面回风巷为工程背景。采用理论分析、物理相似模拟和数值模拟相结合的研究方法,研究了软岩回采巷道围岩塑性区演化规律及失稳机理。结果表明:在围岩应力作用下,肩角剪切裂隙带向上发育,形成“蝶形”塑性区。同时锚固拱内外岩层的变形不协调运动易在锚固端形成水平离层裂隙。该离层裂隙与两肩角的剪切裂隙带相互贯通从而造成锚固拱整体失稳。基于此,提出了高预紧力“倒梯形”注浆锚索与普通锚索协同支护技术,并通过数值模型对优化前后围岩控制效果进行了分析,优化后围岩塑性区显著减小,顶板最大下沉量较原方案下降了50.7%,两帮移近量下降了38.2%,有效解决了软岩巷道大变形问题。

Aiming at the problem of large deformation of soft rock roadway,the project background is the return air roadway at 50213 working face of Guantun coal mine.Using a combination of theoretical analysis,physical similarity simulation and numerical simulation,the evolution law and instability mechanism of the plastic zone of the surrounding rock of the soft rock mining roadway are studied.The results show that under the stress of the surrounding rock,the shoulder shear fracture zone develops upwards,forming a"butterfly"plastic zone.At the same time,the deformation and uncoordinated movement of the rock strata inside and outside the anchoring arch is likely to form horizontal separation cracks at the anchoring end.The separation fissure and the shear fissure zone of the two shoulder angles interpenetrate each other,causing the anchoring arch to lose stability as a whole.Based on this,a high pre-tightening force"inverted trapezoidal"grouting anchor cable and common anchor cable collaborative support technology are proposed,and the control effect of the surrounding rock before and after optimization is analyzed through a numerical model.After the optimization,the plastic zone of the surrounding rock is significantly reduced compared with the original plan,the maximum subsidence of the roof has been reduced by 50.7%,and the displacement of the two sides has been reduced by 38.2%,effectively solving the problem of large deformation of the soft rock roadway.