高渗压环境下工程可利用岩体除经受先期开挖扰动及后续施工造成的反复加卸载作用外，还因地下水的渗透潜蚀，进一步加剧了其内部结构的损伤演化。因此，本课题以渗压环境下卸荷岩石为研究对象，综合采用理论研究、室内试验及数值模拟分析方法，探究了孔压量级及卸荷量级影响下、损伤岩石加卸载过程中的力学响应机制及能量演化特征与能量分配规律；基于弹性模量法和耗散能法，讨论了卸荷岩石加卸载过程中的损伤演化特征；并通过数值模拟揭示了渗压条件下隧洞围岩随开挖进程的应力变形变化特征。主要研究成果如下：

恒定孔压及循环孔压应力路径下，卸荷岩样加卸载过程应力-应变曲线的外包络线、同对应初始孔压下岩石常规三轴压缩试验曲线形态近似，且相同孔压应力路径下各卸荷量级岩样的循环加载曲线形态也基本相似。卸荷岩样加卸载过程应力-应变曲线均可以划分为原生微裂隙压密闭合、弹性压缩、裂纹稳定扩展、裂纹快速发展及峰后变形破坏五个阶段。

卸荷岩样循环加载变形特征与孔压量级、卸荷量级及加载应力水平紧密相关。随初始孔压水平的增加，恒定孔压下30%卸荷岩样的累积应变值呈先增后减趋势，60%卸荷量级岩样应变变化特征与之相反；循环孔压下卸荷岩样的累积应变则均呈现出先减小后增加的变化趋势。

卸荷岩样加卸载过程中的特征能量均随着循环周次的增加呈非线性增长趋势。恒定孔压下卸荷岩样的能量吸收比随加载进程呈先急剧增加-再趋于稳定-后逐渐下降的变化趋势；叠加孔压往复作用时，产生的耗散能整体大于弹性能。弹性模量法定义下卸荷岩样的损伤变量演化特征曲线呈“上凸”形态，而采用耗散能法定义的损伤变量演化特征曲线呈“下凹”形态，且基于能量定义的损伤变量更直观准确。

衬砌支护情况下，压应力主要集中分布在衬砌及洞室围岩位置处，两侧拱腰为压应力集中区；相较仅开挖条件下围岩应力分布，主应力及孔隙水压力均有所降低。洞室围岩仍以收敛变形为主，整体变形量值在施加防护措施后也有所减小。实际隧洞施工过程中，需要综合考虑地层岩性、地质构造、地下水位分布情况等多个因素，以便选择合理有效的加固防护措施，确保施工的安全稳定和工程质量。

Under high osmotic pressure environment, engineering can utilize rock mass, which not only undergoes repeated loading and unloading caused by early excavation disturbance and subsequent construction, but also further intensifies the damage evolution of its internal structure due to groundwater infiltration and erosion. Therefore, this project takes unloading rocks under seepage pressure environment as the research object, and comprehensively adopts theoretical research, indoor experiments, and numerical simulation analysis methods to explore the mechanical response mechanism, energy evolution characteristics, and energy distribution law during the loading and unloading process of damaged rocks under the influence of pore pressure level and unloading level; Based on the elastic modulus method and dissipation energy method, the damage evolution characteristics during the loading and unloading process of unloaded rocks were discussed; And through numerical simulation, the stress and deformation characteristics of tunnel surrounding rock under seepage pressure conditions were revealed as excavation progresses. The main research results are as follows:

(1) Under constant pore pressure and cyclic pore pressure stress paths, the envelope of the stress-strain curve during the loading and unloading process of unloaded rock samples is similar to the conventional triaxial compression test curve under the corresponding initial pore pressure, and the cyclic loading curve shape of each unloading magnitude rock sample under the same pore pressure stress path is also basically similar. It can be divided into five stages: primary microcrack compaction closure, elastic compression, stable crack propagation, rapid crack development, and post peak deformation and failure.

(2) The deformation characteristics of unloading rock samples under cyclic loading are closely related to the magnitude of pore pressure, unloading magnitude, and loading stress level. As the initial pore pressure level increases, the cumulative strain value of the 30% unloaded rock sample under constant pore pressure shows a trend of first increasing and then decreasing, while the strain variation characteristics of the 60% unloaded rock sample are opposite; The cumulative strain of unloading rock samples under cyclic pore pressure shows a trend of first decreasing and then increasing.

(3) The characteristic energy during the loading and unloading process of unloading rock samples shows a non-linear growth trend with the increase of cycle times. The energy absorption ratio of unloaded rock samples under constant pore pressure shows a trend of first increasing sharply, then stabilizing, and finally gradually decreasing with the loading process; When the superimposed pore pressure reciprocates, the overall dissipated energy generated is greater than the elastic performance. The damage variable evolution characteristic curve of unloaded rock samples defined by the elastic modulus method shows an upward convex shape, while the damage variable evolution characteristic curve defined by the dissipation energy method shows a downward concave shape, And the damage variables defined based on energy are more intuitive and accurate.

(4) In the case of lining support, compressive stress is mainly concentrated at the positions of lining and surrounding rock of the tunnel, and the two sides of the arch waist are areas of compressive stress concentration; Compared to the stress distribution of surrounding rock under excavation only conditions, both the principal stress and pore water pressure have been reduced. The surrounding rock of the tunnel still exhibits convergent deformation, and the overall deformation value also decreases after the application of protective measures. In the actual tunnel construction process, it is necessary to comprehensively consider multiple factors such as geological lithology, geological structure, and groundwater level distribution in order to select reasonable and effective reinforcement and protection measures, ensure the safety, stability, and engineering quality of construction.

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