循环荷载作用下盐岩蠕变损伤机理及本构模型研究

With the constructing of salt rock underground storage caverns and compressed air energy storage plants, the creep properties of salt rock under cyclic loading becomes increasingly prominent. The study on creep damage mechanism and constitutive model for salt rock under cyclic load will be carried out in this scientific research subject. Firstly, triaxial compression tests and fatigue tests with real-time CT scan are carried out on salt rock samples. Based on the test results, the difference and relation between fatigue test curves and compression test curves are comparing analyzed, and the change laws of macro mechanics parameter and meso structural of salt rock with the cycle numbers of cyclic loading are analyzed too. Secondly, in terms of real-time CT scan, triaxial creep tests are carried out under constant loading and cyclic loading respectively. Based on the test results, the change laws of macro mechanics index and meso structural with creep time, cycle numbers of cyclic loading and cycle frequency are analyzed, and the difference of creep damage process of salt rock under cyclic loading is effectively analyzed with which of constant loading by integrating two angles of macro and meso. On this basis, the representation of relationship between macro creep properties and meso structure changes of salt rock is proposed, and the creep meso mechanism of salt rock under cyclic loading is further researched. Then, based on the damage mechanics theory and rheology theory, the creep damage model for salt rock under cyclic loading which can consider the coupling effect of creep-fatigue is proposed at last. The research achievement will have important significance for stability analysis and security evaluation in salt rock underground storage caverns and compressed air energy storage plants.

随着我国盐岩地下储存库工程的兴建和盐穴型压气蓄能电站工程的实施，盐岩在循环荷载作用下的蠕变特性问题变得日趋突出。本课题拟对此展开研究，首先，进行三轴压缩试验和CT实时扫描疲劳试验，对比两种情况下盐岩应力—应变曲线的区别和联系，分析疲劳破坏过程中盐岩宏观力学参数和细观结构随荷载循环次数的变化规律；其次，进行恒定荷载和循环荷载三轴蠕变试验，同时进行CT实时扫描，探索盐岩在恒定荷载及循环荷载下宏观特性指标和细观结构对蠕变时间、荷载循环次数及荷载频率的响应规律，并从宏观和细观两个角度对比恒定荷载及循环荷载下盐岩蠕变过程的差异；在此基础上，建立循环荷载下盐岩内部细观结构变化与宏观特性指标的定量关系，揭示循环荷载下盐岩蠕变损伤细观机理，建立循环荷载下可反映盐岩蠕变—疲劳耦合作用的损伤本构模型。课题研究成果对于盐岩地下储存库及盐穴型压气蓄能电站工程在运营期间的稳定性分析和安全性评价等具有重要意义。

随着盐岩地下储存库工程的兴建和盐穴型压气蓄能电站工程的实施，盐岩在循环荷载作用下的蠕变特性问题变得日趋突出，本课题对此展开了研究。（1）基于盐岩及顶板岩层常规压缩试验结果，分析了盐岩及顶板岩层常规压缩破坏过程的特点和围压对岩石强度、变形特性的影响规律，建立了岩石常规压缩破坏过程的经验模型及损伤本构模型；（2）基于盐岩疲劳试验结果，分析了盐岩疲劳变形随荷载循环次数的变化规律和上限应力对盐岩疲劳变形的影响规律，建立了基于反S函数的可反映盐岩疲劳破坏全过程的疲劳本构模型；（3）基于恒定荷载作用下盐岩蠕变试验结果，分析了恒定荷载作用下盐岩蠕变变形随时间的变化规律和应力水平对盐岩蠕变行为的影响规律，建立了恒定荷载作用下盐岩非线性粘弹塑性蠕变模型和基于反S函数的盐岩全过程蠕变模型；（4）基于低频循环荷载作用下盐岩蠕变试验结果，分析了低频循环荷载作用下盐岩变形随偏应力升降的响应规律，建立了低频循环荷载（不考虑疲劳效应）作用下可反映盐岩变形波动性的蠕变模型；（5）基于循环荷载作用下盐岩蠕变试验结果，分析了循环荷载作用下盐岩变形随时间的变化规律和上限应力对盐岩变形的影响规律，并对比分析了恒定荷载、低频循环荷载及循环荷载作用下盐岩变形过程的差异，建立了循环荷载作用下考虑蠕变和疲劳耦合作用的盐岩本构模型；（6）基于FLAC3D软件二次开发平台，将盐岩非线性粘弹塑性蠕变模型进行了二次开发，获得了其计算机应用程序；（7）从唯象学的角度出发，建立了考虑地层蠕变特性的盐岩储气库地面沉降预测模型。研究成果对于盐岩地下储存库及盐穴型压气蓄能电站工程在运营期间的稳定性分析和安全性评价等具有重要意义。