含强弱交界面盐岩-硬石膏夹层组合体静态断裂与蠕变断裂机理研究

The project is closely related to the key scientific problem of static and creep fracture behaviors of compound salt rock-anhydrite sample containing strong and weak interfaces in China. Based on the project of Yunying unground salt gas storage in Hubei province, experimental and theoretical research will be carried out. The main research contents are as follows: by using high-speed 3D-DIC and real-time crack growth tester,the effects of the arrangement and combination mode of strong and weak interfaces and the strength of strong interface on the initiation toughness, propagation toughness, crack initiation point and time, crack growth trajectory and growth rate of creep fracture are studied on the compound salt rock-anhydrite sample only containing strong and the compound salt rock-anhydrite sample containing strong and weak interfaces. Then, numerical simulation and micro-mechanical experiments will be carried out to reveal the mechanism of "synergistic cracking" or "competitive cracking" between the strong and weak interfaces in the fracture process and to determine the "dominant interface" which plays a dominant role in controlling the fracture behavior. Furthermore, based on fracture parameters, fracture mechanism and stress intensity factor of interfacial cracks,static fracture and creep fracture criteria considering the interaction between strong and weak interfaces are established. The criteria are embedded in the numerical simulation software to simulate the damage evolution range of Yunying salt cavern under different working conditions. Finally, based on the simulation results, the optimal design parameters and operation parameters of Yunying salt cavern are proposed.

本项目紧密围绕我国含强弱交界面盐岩-硬石膏围岩静态断裂与蠕变断裂规律这一关键科学问题，依托湖北云应盐岩储气库工程，开展实验和理论研究。主要研究内容为：针对只含强交界面盐岩-硬石膏组合体和同时含强弱交界面盐岩-硬石膏组合体，通过高速3D-DIC和高精度裂缝扩展实时测试仪研究强弱交界面排列组合方式和强交界面强度对组合体试件的起裂韧度、扩展韧度、裂缝起裂点和时间、断裂裂缝轨迹和裂缝蠕变扩展速率的影响规律。继而利用数值模拟和细观力学实验揭示出强弱交界面在试件断裂过程中的“协同起裂”或“竞争起裂”作用机理，并确定出对断裂规律起主导控制作用的“优势交界面”。然后基于实验参数、断裂机理和交界面裂缝应力强度因子建立考虑强弱交界面交互作用的静态断裂与蠕变断裂准则，并将准则嵌入到数值模拟软件中模拟云应盐岩储库在不同工况条件下的损伤演化过程。最后基于模拟结果对云应盐岩储库提出最优化的设计参数和运行参数。

为深入研究含强弱交界面盐岩-硬石膏组合体的静态断裂和蠕变断裂特性，本课题通过宏细观实验研究、理论分析和数值模拟对其力学行为进行了探索，并运用多种相关设备、软件进行实验研究，其中包括自行研发的高温高压固流热耦合三轴万能试验仪、裂缝实时扩展可视化瞬态捕捉记录仪、DIC、电镜SEM、MCT、PFC数值模拟软件等。.本课题的主要研究内容为：.完成了三轴应力处理后的盐岩和硬石膏在不同预制裂缝角度下的破断实验。探究纯盐岩和硬石膏破断特征与细观孔裂隙结构演化规律，对盐岩和硬石膏在不同三轴应力处理后的孔裂隙进行细观实验，揭示了孔隙率、孔径分布、比表面积、分形维数和断面粗糙度的变化规律。.完成了盐岩、硬石膏和盐膏组合体蠕变断裂实验。揭示含强弱交界面盐岩-硬石膏夹层组合体蠕变断裂特征，计算得出含裂缝试件在不同预制裂缝角度的裂缝尖端应力强度因子和裂缝蠕变扩散速率，对静态断裂与蠕变断裂模型进行优化与修正，并对其数值模拟结果的准确性进行了理论计算和实验验证。.完成了含强弱交界面盐岩-硬石膏夹层组合体I±II 型混合型静态断裂韧度数值模拟。研究强弱交界面排列组合方式和强交界面强度对试件静态断裂特征的影响规律，揭示出强弱交界面之间的“协同起裂”或“竞争起裂”作用机理，并最终确定出对组合体静态断裂规律起主导控制作用的“优势交界面”。.在本项目资助下，项目负责人以第一作者/通讯作者共发表了10篇SCI论文，其中以第一作者发表SCI论文7篇，项目成果应用于四川久大荣州盐矿有限公司、江苏新源矿业有限责任公司、中盐金坛盐化有限责任公司等盐矿与储能企业。成果应用在推动我国盐类矿层绿色开采和盐穴储能储废领域的科技进步发挥了重要作用。