基于数值流形方法的岩石热损伤细观机制研究

The rock thermal damage is one of the key scientific problems of deep geotechnical engineering. Thus, it is of great significance to reveal the micro-mechanism of rock thermal damage. Taking the microscopic numerical simulations as the main research technique and combining with laboratory tests, the micro-mechanism of rock thermal damage is studied in this project. The numerical manifold method (NMM) is selected as the basic numerical platform of this project. By incorporating the Voronoi polygons and interface elements, the bonded particle model which fits the rock microstructure characteristic is established. By developing the interface element thermal conduction model which fit the thermal physical characteristics of rock, the micro thermal conduction algorithm for rock is established. Furthermore, by developing the inter-granular fracture model and trans-granular fracture model, an NMM algorithm for analysis microscopic thermal fracture of rock is finally established. Then, the developed numerical algorithm is verified by comparing the numerical results with that of the laboratory tests and the analytical solutions, and the relationship between the micro and macro thermal physical parameters as well as mechanical parameters are studied. At last, numerical tests about rock thermal damage is conducted by considering the real mineral components, the initial damage and the quartz phase transformation of the rock. By combining the results of the numerical tests with that of similar laboratory tests, the heat conduction characteristic and thermal fracture evolution pattern of rock during heating process as well as the mechanical properties of the thermal damaged rock after heating are studied. Based on the above numerical studies, the micro-mechanism of rock thermal damage is revealed, which can provide theoretical support for the deep geotechnical engineering.

岩石热损伤是深部岩土工程所关注的关键科学问题之一，揭示岩石热损伤细观机理具有重要意义。本项目以细观尺度数值模拟为主要研究手段，同时结合室内试验，围绕岩石热损伤的细观机理开展研究。项目以数值流形方法（NMM）为基本平台，引入了Voronoi随机多边形和界面单元来建立符合岩石细观结构特征的颗粒粘结模型；发展了包含界面单元热传导模型的岩石细观热传导NMM算法；通过发展符合岩石细观力学性质的晶间破裂算法和穿晶破裂算法，建立了岩石细观尺度热破裂分析的NMM算法。然后，通过对比室内试验和解析解来验证算法的有效性，并研究宏细观热物理参数和宏细观力学参数的内在关系。最后，在考虑岩石的真实矿物组分、初始损伤、石英相变等因素影响的情况下开展了数值试验，并结合室内试验，研究岩石热处理过程中热传导特性和热破裂的演化规律，研究热损伤后岩石的力学性质和破坏过程，以揭示岩石热损伤的细观机理，为相关岩土工程提供理论支撑。

岩石热损伤是深部岩土工程所关注的关键科学问题之一，揭示岩石热损伤细观机理具有重要意义。本项目针对岩石热损伤细观机理，采用数值模拟和室内试验相结合的方式开展了研究。首先，以数值流形方法（NMM）为基础，通过引入Voronoi随机多边形生成算法和节理单元，建立了表征岩石细观结构的模型；基于岩石细观热传导特征，提出了表征颗粒间传热的节理单元热传导模型和接触热传导模型，据此开发了基于岩石细观结构的热传导NMM算法；基于NMM初应力矩阵特征和热膨胀应力计算算法，建立了岩石热力耦合NMM算法；开发了基于节理单元损伤演化的晶间破裂算法和基于修正的Mohr-Coulomb强度准则的穿晶破裂算法，建立了岩石细观尺度热力耦合破坏过程分析的NMM算法。然后，通过与试验结果或解析解对比，验证了NMM热传导算法的有效性，探讨了宏细观热物理参数的内在关系；通过开展岩石数值试验，并与室内试验结果对比，验证拓展后的NMM细观破裂算法的有效性，并揭示宏细观力学参数的内在关系。接着，基于XRD衍射仪测得了岩石的矿物成分及占比，提出了岩石半随机细观结构模型建模方法；通过数值试验分析，揭示了岩石热处理过程中的热损伤细观机理。最后，开展了岩石热损伤宏细观室内试验，并对比分析数值试验结果和室内试验结果，揭示了热损伤岩石力学性质变化特征和破坏规律，并揭示了其潜在的细观机理。项目开发了岩石热损伤数值分析方法，揭示了岩石热损伤细观机理，为深部高温环境下的岩土工程提供了理论支撑。