【摘要】 地下储气库围岩长期处于复杂疲劳应力状态下,盐岩三轴循环荷载下的变形规律对储气库稳定性分析有参考价值。对8个盐岩试块进行了不同围压、不同应力水平和不同频率条件下的循环荷载试验。对每一试块施加恒定围压和轴向低频循环荷载。对试验参数进行了无量纲处理,分析了应力比强度(广义剪应力强度与球应力的比值)、应力比振幅、上限应力水平、荷载频率、循环次数(N)等对体积应变(?v)的影响。利用函数?v=?lg N+?v0,对每一试块的体积应变–循环次数曲线进行了拟合分析,获得了参数?和?v0随应力比振幅、上限应力水平和频率变化的数学表达式。标准化回归系数分析表明,上限应力水平是影响盐岩体积变形的主要因素,其次是应力比振幅。在高上限应力水平三轴状态下,盐岩主要表现出体积扩大现象。更多还原

【Abstract】 The surrounding rock salt of underground gas storage cavern is subjected to long-term triaxial fatigue stress. The deformation property of rock salt under triaxial cyclic loading is of great importance to the stability of the rock salt cavity. A series of laboratory tests are performed to explore the deformation behavior of eight rock salt specimens under various confining pressures, stress levels and loading frequencies. The axial low-frequency cyclic stress is applied on each salt specimen while the confining pressure is kept steady. The test parameters are processed by the dimensionless method. The effects of the strength of stress ratio(ratio of generalized shear strength to spherical stress), amplitude of stress ratio, level of the maximum stress, loading frequency and loading cycles(N) on the volumetric strain(?v) of rock salt are analyzed. The nonlinear curve fitting is carried out using the function ?v =?lg N+?v0 for a curve of each specimen on the volumetric strain with the cycles. Further, the expressions for the parameters ? and ?v0 with the amplitude of stress ratio, the maximum stress and loading frequency are obtained, respectively. The analysis of standardization regression coefficient indicates that the maximum stress is the key factor that influences the volumetric deformation of rock salt, and the stress amplitude ratio comes the second. It is noted that the rock salt exhibits dilatancy under high maximum stress.更多还原