单轴压缩下单节理砂岩峰前能量自我抑制演化规律

Evolution law of self-suppression of peak energy of single jointed sandstone

  • 摘要: 从能量角度探寻节理对岩体损伤破坏规律的影响,可为工程岩体稳定性分析提供参考。利用室内岩石单轴压缩试验、数字图像相关法以及PFC数值模拟方法,基于岩石能量理论,对单轴压缩下单节理砂岩力学特征和能量自我抑制演化模型的节理倾角效应、节理长度效应特征进行了研究,建立了节理砂岩峰前弹性应变能和轴向应变之间的自我抑制演化模型,并探讨了节理长度、节理倾角及围压对节理砂岩峰前宏细观能量自我抑制演化的影响。研究表明:节理砂岩峰前宏细观能量积聚过程可用其能量自我抑制演化模型来表征,其分别与室内试验结果、数值模拟结果拟合效果良好;从模型参数的演化规律来看,考虑自我抑制效应和不考虑自我抑制效应下,影响能量积聚转化作用机制的节理倾角效应和节理长度效应特征均具有同步性和竞争性,但抑制能量转化作用的机制对峰前能量积聚的最终结果起了决定性作用;高围压条件会削弱节理砂岩峰前细观能量积聚过程的自我抑制作用。同一围压水平下,节理砂岩峰前宏细观能量自我抑制作用随节理倾角增大而先增强后减弱,能量积聚速率先减小后增大,相应的峰值点处的储能极限先减小后增大;随着节理长度的增大,节理砂岩峰前宏细观能量自我抑制作用逐渐增强,能量积聚速率逐渐减小,相应的峰值点处的储能极限逐渐减小。

     

    Abstract: Exploring the influence of joints on the damage and failure law of rock mass from an energy perspective can provide a reference for the stability analysis of engineering rock mass.Using the laboratory rock mechanics test and digital image correlation method and PFC,based on rock energy theory, the me-chanical characteristics of single joint sandstone under uniaxial compression and the joint dip effect and joint length effect characteristics of the energy self-inhibition evolution model were studied.The research established a self-inhibited evolution model between the pre-peak elastic strain energy and axial strain of jointed sandstone, and discussed the influence of joint length, joint dip and confining pressure on the self-inhibited evolution of jointed sandstone pre-peak macro and meso energy.The research shows that the macro and meso energetic energy accumulation process of jointed sandstone before the peak can be char-acterized by its energy self-inhibition evolution model, which fits well with laboratory results and numerical simulation results.From the perspective of the evolution of model parameters, the characteristics of joint dip effect and joint length effect that affect the mechanism of energy accumulation and transformation with or without considering the self-inhibition effect are both synchronous and competitive, but the mechanism of inhibiting energy transformation plays a decisive role in the final result of pre-peak energy accumulation.High confining pressure conditions will weaken the self-inhibition of the meso energy accumulation process in front of the jointed sandstone.Under the same confining pressure energetic, the macro and meso energy self-inhibition of the jointed sandstone in front of the peak first increases and then weakens with the increase of the joint dip.The accumulation rate first decreases and then increases, and the energy storage limit at the corresponding peak point first decreases and then increases.As the length of the joint increases, the macro and meso energy self-inhibition of the jointed sandstone in front of the peak gradually increases, and the energy accumulation rate gradually decreases, the energy storage limit at the corresponding peak point gradually decreases.

     

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