分级卸荷条件下锦屏大理岩流变规律研究

 结合锦屏水电站引水隧洞的工程实际，采用恒轴压分级卸围压的应力路径对锦屏大理岩开展了室内三轴压缩蠕变试验。首先，详细介绍卸围压蠕变试验的过程，并针对轴向和侧向蠕变规律的差异进行对比分析。然后，研究卸荷应力路径下应力状态与岩石蠕变变形的关系，研究结果表明，应力差是决定试样蠕变量的主要因素。最后，以Burgurs模型作为理论模型，在综合考虑试样整体变形的情况下，采用相关试验结果直接确定三维本构方程的模型参数。通过对锦屏大理岩轴向和侧向蠕变变形规律的对比分析，认为2个方向的蠕变变形规律存在明显差异，仅根据轴向蠕变变形规律确定的三维流变本构不能反映侧向的蠕变变形规律。因此，建议在建立三维本构时，必须考虑试样的整体变形特性。

STUDY ON RHEOLOGICAL RULES OF MARBLE IN JINPING HYDROPPWER STATION UNDER CONDITION OF STEP UNLOADING

Triaxial creep test was carried out on marble samples from Jinping Hydropower Station under the condition of step unloading lateral stress and constant axial stress. The test process is introduced and the differences between axial and lateral creep properties are investigated. At the same time，the effect of stress state on the rheological properties of the marble is discussed；and the analysis shows that deviatoric stress is the main factor that affects creep deformation. By applying the Burgurs model as theoretical model to fit the processed creep curves，the parameters of the three-dimensional constitutive model are obtained directly. Based on comparison between the lateral and axial creep properties of the marble，obvious difference is found in the creep deformation law in the two directions；thus，it is unreasonable to propose a constitutive relation only based on the axial deformation. It is recommended that overall deformation property of the rock samples should be considered while proposing a three-dimensional constitutive model for marble from Jinping Hydropower Station.