煤矿井下切顶卸压成巷及围岩控制方案的应用分析

Application analysis of roof cutting and pressure relief roadway formation and surrounding rock control scheme in coal mines

以五矿切顶留巷为研究对象,利用UDEC数值模拟、物理相似模拟分析及工业实验验证的方法对切顶卸压成巷特性及控制方案进行了研究。通过UDEC数值模拟可知,当切顶的高度为7 m时,采空侧的巷道顶板无法切断,导致顶板出现离层情况;当切顶的高度为9 m时,基本顶可以沿着预裂切缝跨落,基本顶中的应力可以降低到19~24 MPa;当切顶高度继续增加时不会再影响应力分布。通过物理相似模拟分析可知,当切顶高度为7 m的时候,基本顶的断裂线处于实体煤帮侧,井下巷道围岩会受到破碎岩层的挤压,造成顶部的离层、垮塌;当切顶高度为9 m的时候,巷道基本顶会顺着预裂切缝断裂,此时在采空区跨落的岩层不会对巷道围岩产生挤压,具有明显的卸压作用;当切顶高度继续增加到12 m时,基本顶可以顺着预裂切缝跨落,但对卸压效果并没有明显的增加。根据现场工业试验验证可知,在切顶高度为9 m的情况下,采用高强锚索补强支护+单体柱支撑+U型钢+金属网挡矸支护能够显著提升围岩稳定性。

Taking the top cutting and retaining roadway of the Five Mines as the research object,the characteristics and control scheme of the top cutting and unloading roadway were studied using UDEC numerical simulation,physical similarity simulation analysis,and industrial experiment verification methods.Through UDEC numerical simulation,it is known that when the cutting height is 7m,the roof of the goaf side roadway cannot be cut,resulting in separation of the roof;When the height of the cutting top is 9m,the basic top can span along the pre cracked cutting seam,and the stress in the basic top can be reduced to 19-24MPa;When the cutting height continues to increase,it will no longer affect the stress distribution.Through physical similarity simulation analysis,it is known that when the cutting height is 7m,the fracture line of the basic roof is located on the side of the solid coal slope,and the surrounding rock of the underground tunnel will be compressed by the fractured rock layer,causing detachment and collapse at the top;When the cutting height is 9m,the basic top of the roadway will fracture along the pre cracked cutting seam.At this time,the rock strata that cross the goaf will not compress the surrounding rock of the roadway and have a significant pressure relief effect;When the cutting height continues to increase to 12m,the basic top can fall along the pre cracked cutting seam,but it does not significantly increase the pressure relief effect.According to on-site industrial tests,it can be verified that using high-strength anchor cable reinforcement support+single column support+U-shaped steel+metal mesh gangue blocking support can significantly improve the stability of surrounding rock when the cutting height is 9m.