Amygdaloidal basalt is a typical rock mass in the dam foundation of the Baihetan hydropower project in southwest China. With rising and drawdown of the reservoir water level, the permeability and creep deformation characteristics of the amygdaloidal basalt are much complicated in the long-term cyclic loading processes. A cyclic loading-unloading creep test on the amygdaloidal basalt was performed to evaluate its deformation and permeability behavior. The results showed that Poisson’s ratio and elastic modulus of the rock specimen varied significantly under different loading processes with a relatively large irreversible deformation. The permeability and strain rates of rock changed in two phases under lower deviatoric stresses, while there are three typical stages of strain growth with the final stress level of 121.8 MPa. For axial stress of 128 MPa, the creep deformation and creep rate in the axial direction are smaller than these in the lateral direction. Before the sample failure, the lateral deformation accelerates earlier than the axial deformation. The results also suggested that the permeability of the rock specimens decreases considerably during each loading process and then tends to be constant with time. No apparent change in steady permeability is observed with variation of stress. For 128 MPa axial stress, the permeability first decreases, then tends to be in a stable value, and at last increases during the sample failure.

中文翻译：

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三轴循环加载蠕变试验下杏仁状玄武岩变形和渗透性能评价

杏仁状玄武岩是西南白鹤滩水电站坝基中的典型岩体。随着储层水位的上升和下降，杏仁状玄武岩的渗透率和蠕变变形特征在长期循环加载过程中变得更加复杂。对杏仁状玄武岩进行了循环加载-卸载蠕变试验，以评估其变形和渗透行为。结果表明，岩石试样的泊松比和弹性模量在不同加载过程下变化显着，具有较大的不可逆变形。在偏应力较低的情况下，岩石的渗透率和应变率分两阶段变化，应变增长分为三个典型阶段，最终应力水平为121.8 MPa。轴向应力为128 MPa时，轴向蠕变变形和蠕变速率均小于横向。在样品失效前，横向变形比轴向变形加速。结果还表明，岩石试样的渗透率在每个加载过程中都显着降低，然后随着时间的推移趋于恒定。随着应力的变化，没有观察到稳定渗透率的明显变化。对于128 MPa的轴向应力，渗透率先降低，然后趋于稳定值，最后在样品破坏过程中增加。结果还表明，岩石试样的渗透率在每个加载过程中都显着降低，然后随着时间的推移趋于恒定。随着应力的变化，没有观察到稳定渗透率的明显变化。对于128 MPa的轴向应力，渗透率先降低，然后趋于稳定值，最后在样品破坏过程中增加。结果还表明，岩石试样的渗透率在每个加载过程中都显着降低，然后随着时间的推移趋于恒定。随着应力的变化，没有观察到稳定渗透率的明显变化。对于128 MPa的轴向应力，渗透率先降低，然后趋于稳定值，最后在样品破坏过程中增加。