冲击扰动下泥页岩剪切蠕变试验及蠕变损伤模型研究

Shear creep test and creep damage model study of mud shale under impact disturbance

  • 摘要: 岩石在应力作用下长期处于蠕变状态,矿山爆破开采过程中产生的冲击扰动效应会加速岩石的损伤积累,严重威胁着矿山边坡的稳定性。以黄山石灰石矿山边坡软弱夹层中的泥页岩为研究对象,通过开展不同冲击能量及不同冲击次数下的剪切蠕变试验,分析冲击扰动影响下泥页岩的蠕变力学特性,并引入割线模量法量化冲击损伤,分析了冲击损伤的演化规律。通过引入Weibull分布函数表征应力损伤因子,并由广义损伤理论推导出应力−冲击耦合损伤因子,然后根据对黏度系数的变化分析引入冲击损伤度及修正系数改进黏性元件,最后将耦合损伤因子与冲击损伤改进元件代入西原模型中,建立了一种新的蠕变损伤模型。根据试验结果,采用差分进化算法并依托1stopt全局优化软件对模型进行参数辨识。基于上述研究,得到如下结果:随着冲击能量及冲击次数的增加,泥页岩的长期强度及总蠕变时间逐渐减小,冲击损伤度提高,其破坏特征由脆性破坏逐渐变为典型的塑性破坏;在低剪应力水平下,泥页岩对冲击扰动敏感度较低,随着剪应力水平的提高,泥页岩对冲击扰动敏感度提高,冲击损伤度提升愈快;模型拟合数据与试验数据匹配度较高,蠕变损伤模型能够较好地描述冲击扰动下泥页岩的蠕变特征。研究结果可为矿山边坡的防灾监控与稳定性分析提供理论依据。

     

    Abstract: The rock is in a creeping state for a long time under stress, and the impact disturbance effect generated during the mine blasting and mining process will accelerate the accumulation of rock damage, which seriously threatens the stability of the mine slope. Taking the shale in the soft interlayer of the slope of Huangshan limestone mine as the research object, the creep mechanical characteristics of the mud shale under the influence of impact disturbance were analyzed by carrying out shear creep tests under different impact energies and different impact times, and the secant modulus method was introduced to quantify the impact damage, and the evolution law of impact damage was analyzed. By introducing the Weibull distribution function to characterize the stress damage factor, and deriving the stress-impact coupling damage factor from the generalized damage theory, then introducing the impact damage degree and correction coefficient to improve the viscous element according to the change analysis of the viscosity coefficient, and finally substituting the coupled damage factor and impact damage improvement element into the Nishihara model, a new creep damage model is established. According to the experimental results, the differential evolution algorithm is used and the parameters of the model are identified by relying on the 1stopt global optimization software. Based on the above research, the following results are obtained: with the increase of impact energy and impact frequency, the long-term strength and total creep time of mud shale gradually decrease, the impact damage degree also increases, and its failure characteristics gradually change from brittle failure to typical plastic failure; under low shear stress level, the sensitivity of mud shale to impact disturbance is low, but with the increase of shear stress level, the sensitivity of shale to impact disturbance also increases, and the impact damage degree increases faster; the model fitting data matches the experimental data is high, and the creep damage model can better describe the creep characteristics of mud shale under impact disturbance. The research results can provide a theoretical basis for disaster prevention monitoring and stability analysis of mine slopes.

     

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