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高德煤矿花岗岩蠕变损伤模型研究

Study on creep damage model of granite in Gaode Coal Mine

  • 摘要: 为了研究高德煤矿围岩的蠕变特性以及加载过程中的损伤演化性质,对花岗岩试样进行了分级加载蠕变试验,基于Burgers模型引入改进的Kachanov损伤模型,建立了能描述加速蠕变阶段的蠕变损伤模型,通过数值模拟计算对考虑和不考虑损伤的巷道控制点的变形量进行对比,探讨损伤模型在实际工程中的运用。研究结果表明:由径向蠕变确定的岩石长期强度小于轴向长期强度,且径向蠕变较轴向蠕变更加敏感;当应力水平达到径向长期强度时,开始出现扩容现象,当应力水平达到轴向长期强度时,体积应变开始由正值变为负值。结合轴径向蠕变试验曲线,对蠕变损伤模型参数进行辨识,决定系数达到了0.97以上,模型曲线与试验曲线吻合度高,验证了所建立蠕变损伤模型的合理性;建立的蠕变模型考虑损伤比不考虑损伤的位移大许多,考虑损伤最大变形比不考虑损伤最大变形增大约0.055 27 mm,验证了蠕变损伤模型可以更好地反映巷道围岩的劣化效应,对于巷道的后期支护与安全具有重大指导意义。

     

    Abstract: In order to study the creep properties of the surrounding rocks of Gaode Coal Mine and the damage evolution properties during loading, a graded loading creep test on granite samples was performed.Then, the improved Kachanov damage model was introduced based on the Burgers model, and the damage creep model which can describe the accelerated creep stage was established. The numerical simulation was used to compare the deformation of roadway control points with and without considering damage, and the application of damage model in practical engineering was discussed.The test results show that the long-term strength of the rock determined by radial creep is less than the axial long-term strength, and the radial creep is more sensitive than the axial creep, and when the stress level reaches the radial long-term strength, expansion begins to occur.When the stress level reached the axial long-term strength, the volume strain begins to change from positive to negative.Combined with the axial radial creep test curve, the parameters of creep damage model are identified, the decision coefficient reaches more than 0.97, the model curve is in good agreement with the test curve, and the rationality of the creep damage model is verified.The established rheological model considering the damage is much larger than the displacement without considering the damage. The maximum deformation of the damage considering the damage is about 0.055 27 mm larger than the maximum deformation without considering the damage. It is hence verified that the creep damage model can better reflect the deterioration effect of surrounding rock of roadway and has important guiding significance for the later support and safety of roadway.

     

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