水电资源是可持续利用的清洁能源。大型水电工程建设与运行期所涉及的岩质边坡开挖支护及变形失稳问题，是制约水工岸坡工程设计与安全运行的重要课题。本文依托国家自然科学基金面上项目《季冻区水库边坡消落带开挖卸荷岩体力学特性及其变形破坏机理研究，51979218》，根据水工开挖岸坡的赋存环境，以开挖扰动区卸荷岩体为对象，考虑了分步开挖、干湿循环、承压浸泡等因素影响岸坡变形的作用机理；综合采用理论分析、室内试验与细观测试相结合的研究方法，开展涉水岸坡开挖卸荷岩体力学特性分析方面的研究工作。主要研究成果如下：

1）结合库岸岩质边坡施工过程实施了室内三轴分级卸荷试验，获取了不同初始应力水平和不同卸荷量级下的卸荷试样；基于应力路径和卸荷量级及破裂特征，将卸荷损伤试样加卸载过程划分为五个阶段。结果表明，卸围压是引起试样损伤的主要因素，初始围压与卸荷量级控制着试样的卸荷损伤程度；初始围压越大，卸荷量级越大，卸荷响应越显著。同时，室内冻融试验表明，冻结时间越长，卸荷损伤越明显，冻结作用加剧了试件卸围压过程的损伤幅度。

2）以卸荷损伤试样为对象，依次开展了干湿循环试验、波速测定、核磁共振分析，以及三轴再加载试验。结合试样的孔隙结构、力学特性及破裂特征，分析了干湿循环作用对卸荷损伤试样物理力学性质的影响。研究了试样质量、波速、核磁T₂谱分布及谱面积，随干湿循环次数变化的相关性。

3）以冻结后卸荷损伤试样为对象，依次开展了变幅承压浸泡循环试验、波速测定、核磁共振测试及单三轴再加载试验。综合分析了试样全应力应变曲线与力学参数伴随冻结天数的变化规律，获取了质量、波速、核磁T₂谱分布与谱面积伴随冻融循环次数的演化规律，对比研究了应力应变曲线、宏观力学参数随循环次数的变化规律与试样破裂特征，探究了承压浸泡作用影响下冻结试样物理力学性质的变化规律。

4）结合干湿循环条件下卸荷损伤三轴再加载试验结果，推导了“卸荷-干湿循环”条件下的统计损伤本构模型；根据承压浸泡环境下冻结后卸荷试样的单三轴再加载试验数据，构建了“冻结-卸荷-承压浸泡”条件下的统计损伤本构模型；结合试验所得应力应变曲线，进行了所建本构模型的验证及改进工作，模型曲线与试验结果吻合效果较好。

Hydropower resources are sustainable and clean energy. The problems of rock slope excavation support and deformation instability involved in the construction and operation of large-scale hydropower projects are important issues that restrict the design and safe operation of hydraulic bank slope projects. In this paper, relying on the National Natural Science Foundation of China's project "Research on the mechanical properties and deformation and failure mechanism of rock mass during excavation and unloading of the slope of the seasonally frozen reservoir slope, 51979218". According to the occurrence environment of the hydraulic excavation bank slope, taking the unloading rock mass in the excavation disturbed area as the object, the action mechanism of partial excavation, dry-wet cycle, pressure soaking and other factors affecting the deformation of the bank slope is considered. Comprehensive theoretical analysis, laboratory test, meso-test and numerical simulation are adopted to study the mechanical characteristics analysis and stability analysis of excavated unloading rock mass on wading bank slope. The main research results are as follows:

1) Combined with the construction process of reservoir bank rock slope, the triaxial graded unloading test was carried out, and the unloaded samples under different initial stress levels and different unloaded orders were obtained; Based on the stress path, unloading magnitude and fracture characteristics, the loading and unloading process of unloaded damaged samples was divided into five stages. The results show that the unloaded confining pressure is the main factor causing the damage of the samples, the initial confining pressure and the unloading magnitude control the unloaded damage degree of the samples. The greater the initial confining pressure, the greater the unloading magnitude and the more significant the unloading response. At the same time, the freezing-thawing test shows that the longer the freezing time, the more obvious the unloaded damage, and the freezing effect intensifies the damage amplitude in the process of unloading confining pressure.

2) Taking the unloading damaged specimen as the object, the dry-wet cycle test, wave velocity measurement, NMR analysis and triaxial reloading test were carried out in turn. Combined with the pore structure, mechanical properties and fracture characteristics of the specimen, the influence of dry-wet cycle on the physical and mechanical properties of the unloading damaged specimen was analyzed. The correlation of sample mass, wave velocity, T₂ spectrum distribution and spectrum area of nuclear magnetic resonance with the change of dry-wet cycles was studied.

3) Taking the unloaded damaged samples after freezing as the object, the cyclic test of variable amplitude pressure soaking, wave velocity measurement, NMR test and uniaxial and triaxial reloading test were carried out in turn. The variation law of the total stress-strain curve and mechanical parameters with freezing days was comprehensively analyzed, and the evolution law of mass, wave velocity, T₂ spectrum distribution and spectral area with the number of freezing-thawing cycles was obtained. The variation law of stress-strain curve, macroscopic mechanical parameters with the number of cycles and the fracture characteristics of samples were compared. The changes of physical and mechanical properties of frozen samples under the influence of pressure immersion were studied.

4) Based on the triaxial reloading test results of unloaded damage under the condition of dry-wet cycle, the statistical damage constitutive model under the condition of "unloading-dry-wet cycle" is derived. According to the data obtained from uniaxial and triaxial reloading tests of frozen unloaded samples under pressure immersion environment, a statistical damage constitutive model under the condition of "freezing-unloading-pressure immersion" is constructed. Combined with the stress-strain curve obtained from the test, the established constitutive model is verified and improved, and the model curve is in good agreement with the test results.

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