复合动力灾害危险下被保护层回采巷道位置优化

Optimization of the roadway location in protected seam with composite dynamic hazards

针对突出煤层中回采巷道围岩易受采动影响而产生应力集中,存在围岩冲击动力失稳危险,进而可能诱发冲击-突出复合动力灾害的难题,以淮南矿区朱集西矿保护层开采为工程背景,分析了影响煤岩冲击-突出复合动力灾害的主要因素,计算了被保护层卸压范围,模拟分析了被保护层中回采巷道布置在不同位置时其围岩应力峰值、塑性区范围及峰值点煤岩应力梯度的变化特征,确定了被保护层回采巷道复合动力灾害防治优化区及局部预警防治措施。结果表明:采深、煤岩力学性质、煤岩结构、构造应力是影响煤岩复合动力灾害的主要因素;保护层开采可降低被保护层煤岩冲击-突出复合动力灾害危险性;保护层回采后,被保护层中回采巷道位置从外错向内错变化时,其围岩应力峰值、峰值点处煤岩应力梯度逐渐降低,围岩塑性范围先增大后减小;确定被保护层回采巷道内错17~30 m范围为防治煤岩复合动力灾害优化区。

The surrounding rock of roadway would fracture and become failure under the high stress induced by mining or geological structures, which might further cause bumps and burst of coal or gas. In order to prevent the composite dynamic disaster comprising bumps and burst of coal or gas, the key factors which affect the composite disaster are analyzed on the basis of the engineering background of Zhujixi coal mine. The stress relief area produced by protective seam mining is calculated. Additionally, as the location of the roadway in protected seam varying, the stress peak value, the plastic zone and the stress peak gradient of its surrounding rock are studied, and the optimization of its location for prevent-ing composite dynamic disaster is determined. The results show that the risk of composite disaster is determined by several factors, such as mining depth, mechanical property and structural character of coal and rock as well as geological structures. The protective seam mining would reduce the burst risk of composite dynamic disaster in the protected coal seam. With the relative horizontal distance between roadway in protective seam and that in protected seam varying from -35 m to 35 m, the stress peak val-ue and its gradient in surrounding rock decrease gradually and the plastic ratio increases firstly and then decrease. The relative horizontal distance between 17 m and 30 m is the comparatively safety area for roadway tunneling in the protected seam.