许文松,赵光明,孟祥瑞,等. 真三轴加卸载岩体各向异性及能量演化机制[J]. 煤炭学报,2023,48(4):1502−1515. doi: 10.13225/j.cnki.jccs.2022.0766
引用本文: 许文松,赵光明,孟祥瑞,等. 真三轴加卸载岩体各向异性及能量演化机制[J]. 煤炭学报,2023,48(4):1502−1515. doi: 10.13225/j.cnki.jccs.2022.0766
XU Wensong,ZHAO Guangming,MENG Xiangrui,et al. Anisotropy and energy evolution mechanism of rock mass under true triaxial loading-unloading[J]. Journal of China Coal Society,2023,48(4):1502−1515. doi: 10.13225/j.cnki.jccs.2022.0766
Citation: XU Wensong,ZHAO Guangming,MENG Xiangrui,et al. Anisotropy and energy evolution mechanism of rock mass under true triaxial loading-unloading[J]. Journal of China Coal Society,2023,48(4):1502−1515. doi: 10.13225/j.cnki.jccs.2022.0766

真三轴加卸载岩体各向异性及能量演化机制

Anisotropy and energy evolution mechanism of rock mass under true triaxial loading-unloading

  • 摘要: 地下工程开挖过程中围岩处于极其复杂的应力环境中,尤其是在其各向异性的影响下,动力灾害的发生存在隐蔽性。采用真三轴卸荷扰动岩石测试系统对砂岩进行不同主应力方向加卸载试验,研究真三轴不同主应力加卸载条件下高应力岩体力学特性与破坏特征,分析不同主应力加卸载岩体次生各向异性及能量演化机制。结果表明:① 在岩体次生各向异性影响下, \sigma _1 (第一主应力)进行循环加卸载过程中, \varepsilon _2 (第二主应变)和 \varepsilon _3 (第三主应变)呈现相反变化, \varepsilon _V (体积应变)先压缩再膨胀,最终表现出膨胀的宏观现象;② 高围压岩体 \sigma _3 (第三主应力)卸载时, \varepsilon _1 产生压缩, \varepsilon _2 和 \varepsilon _3 产生膨胀变形, \varepsilon _2 变化量小于 \varepsilon _3 ,卸荷方向变形由线弹性状态转变为弹−塑非线性;③ \sigma _1 和 \sigma _3 卸载岩体积聚的能量差异较大, \sigma _1 卸载是一个能量释放的过程, \sigma _3 卸载是一个能量积聚的过程,卸荷方向的能量变化特征决定了其余2个诱发方向的能量积聚、释放规律, \sigma _3 卸载岩体的极限储存能量降低,且 \sigma _2 (第二主应力)卸荷时随着 \sigma _1 的增大加快了岩石的破坏,表明岩体卸载比加载更容易破坏;④ \sigma _3 卸荷速度越快,破坏时所释放的能量增加、耗散能降低,卸荷方向岩体能量密度和总积聚能量密度减小。动力事故发生的主要原因是岩体内部能量的积聚释放,岩体次生各向异性对岩体自身极限储存能存在很大影响,研究真三维加卸载次生应力对岩石极限储存能的影响特征为冲击地压防止提供了参考。

     

    Abstract: In the process of underground excavation, the surrounding rock is in a very complex stress environment, especially under the influence of its anisotropy, the occurrence of dynamic disaster is hidden. In this paper, the loading and unloading tests of sandstone in different principal stress directions were carried out by using the true triaxial unloading disturbed rock test system. The mechanical properties and failure characteristics of true triaxial under different principal stresses were studied, the energy evolution mechanism in other directions induced by loading and unloading of different principal stresses was analyzed. Results showed that under the influence of rock mass secondary stress anisotropy, during the cyclic loading and unloading process of the first principal stress, the strain in other directions shows opposite deformation. The volumetric strain compresses first and then expands, and the final volumetric strain shows a macroscopic phenomenon of expansion. When the third principal stress of high confining pressure rock mass is unloaded, the first principal stress produces a compression deformation, while the second and third principal stresses produce an expansion deformation. The deformation of the second principal stress is less than that of the third principal stress, and the deformation in unloading direction changes from linear elastic state to elastic-plastic nonlinear state. The accumulated energy of rock mass is a great difference between the first principal stress unloading and the third principal stress unloading. The energy variation characteristics of unloading in the dominant direction determine the energy accumulation and release law in the other two induced directions. The limit stored energy of the third principal stress unloading rock decreases, and the second principal stress accelerates the rock failure with the increase of the first principal stress, which verifies that the rock is easier to be destroyed by unloading than by loading. The higher the unloading rate of the third principal stress, the higher the energy released and the lower the dissipated energy, and the lower the energy density and total accumulated energy density in the unloading direction of rock mass. The main cause of dynamic accidents is the accumulation and release of energy in rock mass. The secondary anisotropy of rock mass has a great influence on the ultimate stored energy of rock mass. The study on the influence characteristics of three-dimensional loading and unloading secondary stress on the ultimate stored energy of rock mass provides a reference for preventing rock burst.

     

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