真三轴循环荷载下含裂缝砂岩能量和损伤分析

    Energy and damage analysis of fractured sandstone under true triaxial cyclic loading

    • 摘要: 探究真三轴循环荷载作用下含裂缝砂岩能量演化有助于明确岩石损伤破坏规律。开展了真三轴循环加卸载试验,分析了吸收总能量、弹性能、耗散能和塑性变形能的演化特征,并建立岩石损伤评价模型,结合断裂面细观损伤特征,探讨了岩石损伤破坏规律。结果表明:随着裂缝角度增大,试样强度越大,破坏时吸收总能量越大,分别为0.238、0.276、0.307、0.332 MJ/m3;试验时吸收总能量、弹性能、耗散能均逐渐增加,塑性变形能先减小后增大;通过滞回环能量和总耗散能量,建立岩石损伤破坏评价指标,两者评价结果一致,岩石损伤程度随加卸载进行呈非线性变化;试样破坏时经历循环加卸载次数越多,受挤压摩擦程度越高,断裂面细观形貌越复杂。

       

      Abstract: Exploring the energy evolution of fractured sandstone under true triaxial cyclic loading is helpful to clarify the law of rock damage and failure. The evolution characteristics of total absorbed energy, elastic energy, dissipated energy and plastic deformation energy during the test were systematically analyzed. A rock damage evaluation model was established, and the rock damage failure law was discussed in combination with the mesoscopic damage characteristics of the fracture surface. The results show as follows: with the increase of crack angle, the greater the peak strength of the sample during failure, the greater the total absorbed energy, they were 0.238, 0.276, 0.307 and 0.332 MJ/m3, respectively; the total absorbed energy, elastic energy and dissipated energy increase gradually during the whole test process, while the plastic deformation energy decreases first and then increases; based on hysteretic loop energy and total dissipated energy, an evaluation index was established to describe rock damage, and the results of the two evaluation methods are consistent, and it is found that the rock damage degree changes nonlinear with loading and unloading during the test; the number of cyclic loading and unloading during the failure of the sample has a significant influence on the internal damage of the sample. The more times of cyclic loading and unloading, the higher the degree of extrusion friction and the more complex the micromorphology of the fracture surface.

       

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