开卸压槽防治岩爆的数值模拟研究
Numerical simulation on rockburst prevention by cutting stress-relief slots
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摘要:
随着岩石工程逐渐向深部发展,高地应力导致的岩爆灾害日益凸显,而开卸压槽或是主动降低围岩高地应力、防治岩爆的有效措施之一。为研究开卸压槽对岩爆的防治效果,本文利用离散元数值模拟方法对巷道中不同开槽卸压方案进行了对比分析。研究结果表明:开挖后的巷道围岩环向应力增大、易发生岩爆,在围岩中开槽可在卸压槽周围形成三角形的应力降低区,并将高应力区转移到卸压槽底部,从而达到防治岩爆的效果。但开槽卸压的效果会受其具体位置影响,且在地应力较高(≥50 MPa)时,单独开卸压槽会造成局部围岩破碎,破坏围岩的完整性,进而诱发岩爆。此外,水平侧压力系数较小时,在不同位置开槽释放的弹性应变能近似相等,水平侧压力系数较大时,在巷道顶板处开槽能量释放效果要优于巷道侧帮开槽。因此,在实际工程中,应根据巷道围岩的地应力条件(地应力大小、侧压力系数等)和围岩稳固性选择合适的开槽方式、开槽位置和支护方式来防治岩爆。
Abstract:With the gradual development of rock engineering to the deep, rockburst disaster caused by high geo-stress is getting worse.Cutting stress-relief slots may be one of the effective measures to actively reduce the high geo-stress of surrounding rock and prevent rockburst.In order to explore the prevention effect of slotting on rockburst, this paper conducts different slotting schemes via the discrete element numerical simulation method for comparison and analysis.The results show that the circumferential stress of a roadway will increase after excavation, and the surrounding rock is prone to cause rockburst.Slotting in the surrounding rock can form a triangular low stress area around the slot, and transfer the high stress zone to the slot bottom, so as to achieve the effect of preventing rockburst.However, the effect of stress relief by slotting will be affected by its specific location, and when the geo-stress is high(≥ 50 MPa), cutting stress-relief slots will cause damage to the surrounding rock and destroy its integrity, and induce rockburst.In addition, when the horizontal lateral stress coefficient is small, the elastic strain energy released by slotting at different positions is very similar, but when the horizontal lateral stress coefficient is large, the energy release effect of slotting at the roadway roof is better than that at the roadway side.Therefore, in engineering practice, appropriate slotting method, position and support measures should be comprehensively adopted to prevent rockburst according to the geo-stress conditions(stress level, lateral stress coefficient, etc.) and the stability of surrounding rock of a roadway.