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动载冲击地压巷道围岩稳定性多层次控制技术

Multi-layer control technologies for surrounding rock stability of dynamic-loading rock burst roadway

  • 摘要: 针对动载巷道易发生冲击地压的问题,以义马矿区动载冲击地压巷道为工程背景,采用现场实测、实验室试验、数值模拟相结合的方法,统计分析了动载冲击地压巷道冲击破坏特征和破坏原因,提出了动载冲击地压巷道围岩 “深部卸压-浅部强支-巷表防护”多层次控制技术。研究结果表明:义马矿区动载扰动冲击地压巷道冲击破坏特征主要表现为:①巷道围岩瞬时变形量大;②巷道底鼓严重;③变形破坏程度和震源能量正相关;④冲击破坏之前,巷道围岩缓慢变形严重;⑤锚杆支护体系严重失效。巷道冲击破坏的主要原因为:高原岩应力和采动应力叠加形成的高静载应力集中、坚硬顶板脆断形成的动载扰动、巷道围岩“外碎内脆”的结构特性以及锚杆支护参数不合理导致的巷道围岩承载能力低。大直径钻孔卸压可以降低应力集中程度和范围,减小冲击破坏释放的能量,减缓动载对巷道围岩的扰动,从而降低巷道围岩发生冲击破坏的风险;针对不同锚固围岩破坏模式,采用加长或全长高预应力锚固、超高强度锚杆以及全断面支护,辅以金属可缩性支架防护巷道空间,可以有效提高冲击地压巷道围岩的自身的抗冲击性能。经实践,监测区域巷道围岩未发生冲击破坏,巷道位移和锚杆(索)受力均在允许范围内,验证了控制技术的可行性。

     

    Abstract: Rock burst is one of the main disasters that threaten the safe and efficient mining in Chinese coal mines. The dynamic load roadway of Yima mining area was taken as the engineering background. The field measurement, laboratory test and numerical simulation were combined to analyze the dynamic load roadway. The characteristics of impact damage and the causes of damage were proposed. The multi-level control technologies of "deep area pressure relief - shallow area strong support - roadway surface protection" of surrounding rock of dynamic pressure roadway wereput forward. The results show that the main bursting characteristics of the dynamic pressure roadway in the Yima mining area are as follows: ①The instantaneous deformation of the surrounding rock of the roadway is large; ②The floor heave of the roadway is serious;③The deformation degree is positively correlated with the source energy; ④The surrounding rock of the roadway is slowly deformed seriously before bursting failure; ⑤The bolt support system seriously failed. The main causes are concentration of high static-loading stress caused by superposition of plateau rock stress and mining stress, dynamic load disturbance formed by brittle fracture of hard roof, struct ural characteristics of "external fragile and internal brittle"of surrounding rock of roadway and unreasonable bolt supporting system. The large-diameter borehole pressure relief can reduce the degree and scope of stress concentration, reduce the magnitude of energy release during the burst failure of deep surrounding rock, increase the distance and attenuation coefficient of dynamic load propagation, slow down the disturbance of the rock vibration load on the roadway surrounding, thereby reducing the risk of surrounding rock of the roadway.The model adopts extended or full-length high-prestressed anchoring, ultra-high-strength anchor and full-section support, supplemented by metallic yieldable support to protect the roadway space, which can effectively improve the ability of resisting burst and absorbing energy of roadway surrounding.Based on the above research results,the field practice of stability control for roadway surrounding rock under dynamic load was carried out. The monitoring result showed that rock burst has not occurred in the monitoring surrounding rock, with the deformation of roadway and the forces of bolts and cables both within the allowable range, which verified the feasibility of theoretical analysis and controlling strategies.

     

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