中文摘要：

利用自行设计的热-水-力（THM）耦合断裂试验和扫描电镜试验，研究脆性岩石THM耦合断裂的宏微观特征；通过有限元法和新型应力强度因子比断裂准则，判断THM耦合断裂模式，揭示出THM耦合断裂机制。结果表明：红砂岩试件具有3种THM耦合宏观断裂轨迹和对应的3种THM耦合微观断裂特征，即低温、低水压、高围压条件下的断裂轨迹为横向断裂，微观上表现为穿晶的剪切断裂：高温、高水压、低围压条件下的断裂轨迹为纵向断裂，微观上表现为沿晶的拉伸断裂；中等温度、中等水压、中等围压条件的断裂轨迹为双向断裂，微观上表现为含沿晶和穿晶的拉剪复合型断裂。基于有限元法和新型最大应力强度因子比断裂准则判断出的红砂岩试件THM耦合断裂模式与基于宏微观断口分析得到的THM耦合断裂机制完全一致。

英文摘要：

Coupled thermo-hydro-mechanical（THM） fracturing tests and scanning electron microscope（SEM） tests were performed to study the macroscopic and microscopic characteristics of coupled THM fracturing of brittle rocks. Finite element method and a new fracture criterion on the ratios of stress intensity factor were applied to predict the fracturing mode under THM coupled condition. The red sandstone specimens are found to have three types of modes of fracturing macroscopically with the corresponding fracturing features microscopically under different THM coupling conditions. Transverse fracturing occurs macroscopically and transgranular shear fractures occur microscopically for the specimens under low temperature, low hydraulic pressure and high confining pressure. Longitudinal fracturing occurs macroscopically and intergranular tensile fractures occur microscopically for the specimens under high temperature, high hydraulic pressure and low confining pressure. Cross directional（transverse and longitudinal） fracturing occurs macroscopically and mixed fractures（transgranular and intergranular） occur in the specimens under medium temperature, medium hydraulic pressure and medium confining pressure. The predicted modes of fracturing under THM coupling with the finite element method and the new fracture criterion of ratios of stress intensity factor are found to be in good agreements with that obtained with the fractographic analysis.