采动影响下坚硬岩桥型断层活化与储能演变规律

Evolution law of the activation and energy storage of fault with hard rock bridge under mining influence

  • 摘要: 断层阻滑结构的存在会改变断层能量积聚与滑移行为规律,导致断层活化失稳机理与以往存在较大差异。为研究采动影响下坚硬岩桥型断层活化及储能的演化规律,理论分析了含坚硬岩桥型阻滑结构的断层活化条件;采用物理模拟试验方法,研究了开采扰动下含坚硬岩桥断层的滑移规律,分析了含坚硬岩桥与无阻滑结构的断层活化差异特征,研究了工作面回采过程中含坚硬岩桥与无阻滑结构的断层带正、剪应力变化特征;采用数值模拟方法,研究了临近断层开采过程中含坚硬岩桥与无阻滑结构的断层带应力分布与能量积聚规律。研究结果表明:开采扰动下含坚硬岩桥的断层呈现了更强的非均匀性滑移,但断层的滑移量明显减小,活化程度降低,坚硬岩桥可增加断层的稳定性,其稳定性的提高主要体现在断层面黏聚力的增加;靠近工作面的坚硬岩桥应力集中程度最高,最易发生剪切破坏,但在一定程度上坚硬岩桥会分散应力集中带;对于无阻滑的断层带,其弹性应变能密度随靠近断层开采而逐步增高,但增加幅度有限,且弹性应变能密度峰值始终呈现在工作面前方区域;而坚硬岩桥的存在改变了断层带能量的分布规律,其应变能密度峰值主要聚集在坚硬岩桥与断层带接触处位置。越靠近岩桥的断层带,其滑移挤压程度越高,能量积聚程度也越高;含坚硬岩桥的断层能量积聚程度远大于无阻滑结构断层,阻滑结构可大幅度提升断层带储能潜力。

     

    Abstract: The presence of slide-resistant structures within faults alters the laws of energy accumulation and slip behavior, resulting in significant differences in the mechanisms of fault activation and instability compared to conventional understanding. To study the evolution laws of activation and energy storage of hard rock-bridge-type faults under mining influence, the activation conditions of faults with slide-resistant structures of hard rock bridges were theoretically analyzed. The slip laws of faults with hard rock bridges under mining disturbances was studied by physical simulation experiments. The differential characteristics of fault activation between faults with hard rock bridges and those without slide-resistant structures were analyzed. Moreover, the variation characteristics of normal and shear stresses in the fault zones with hard rock bridges and without slide-resistant structures during the working face extraction process were studied. Using the numerical simulation method, the stress distribution and energy accumulation laws in the fault zones with hard rock bridges and without slide-resistant structures during the mining process near the fault were studied. The research results indicate that faults with hard rock bridges under mining disturbances exhibit more pronounced non-uniform slip behavior. However, the fault slippage amount is significantly reduced, and the degree of activation is decreased. The hard rock bridges can enhance fault stability, and this improvement in stability is primarily reflected in the increased cohesion of the fault surface. The hard rock bridge near the working face has the highest stress concentration and is most prone to shear failure, but to a certain extent, the hard rock bridge will disperse the stress concentration zone. For fault zones without slide-resistant structures, the elastic strain energy density gradually increases as mining approaches the fault, but the extent of increase remains limited, and the peak value of elastic strain energy density consistently occurs in the area ahead of the working face. However, The existence of hard rock bridge alters the energy distribution law in the fault zone, with the peak of strain energy density is mainly concentrated in the contact between hard rock bridge and fault zone. The closer locations within the fault zone is to the rock bridge, the higher the degree of slip compression and the higher the degree of energy accumulation. The energy accumulation in faults containing hard rock bridges is significantly greater than in faults without slide-resistant structures. The slide-resistant structures can greatly enhance the energy storage potential of fault zones.

     

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