本项目针对水工高压隧洞在高地温梯度场中力学行为的特殊性，采用试验研究、理论分析、数值计算与工程实践有机结合的方法，系统开展高地温梯度下水工压力隧洞的承载特性研究。通过可模拟高地温梯度及THM耦合作用的模型试验，结合现场原型测试，在获取高地温梯度水工高压隧洞的力学响应特性与THM耦合作用特征的基础上，建立考虑脆性材料峰后强度劣化的含损伤演化的THM-损伤耦合计算模型，实现高地温梯度水工高压隧洞力学响应的合理预测，进而利用THM-损伤计算模型推演各种环境、运行工况和加固条件下水工高压隧洞的力学行为演化过程与破坏模式，由此揭示高地温梯度水工高压隧洞THM耦合作用下的承载特性；最后通过西部地区典型工程应用研究，进一步深化对其承载特性的认识，验证和完善所提出的理论与模型。通过本项目的基础性研究，为高地温地区水工隧洞结构设计理论体系的构建以及相关规范的制订提供科学依据。

Aiming to the specificity of mechanical behavior of hydraulic high pressure tunnel in the high geothermal gradient field, its bearing behaviors are studied based on experimental study, monitoring data in situ, theoretically analysis, numerical calculation and engineering application. The mechanical response characteristics and mode of coupled thermo-hydro-mechanical-damage (THM-D) are obtained by means of laboratory test and site test. A THM-D computation model considering strength degradation of post-peak brittle material and damage evolution process is proposed to describe the mechanical response of hydraulic pressure tunnel. Then, the proposed models are used to simulate the mechanical behavior of hydraulic pressure tunnels under complex environment and different operation condition in order to reveal the working mechanism of hydraulic pressure tunnels under high temperature gradient conditions. Finally, the proposed theory and model are improved by application study on typical engineering case in high geothermal region of western China. The study results will provide scientific references for building design theories system and formulating design specifications for hydraulic pressure tunnel in high geothermal region.