高渗压条件下裂隙岩体水力耦合试验方法与作用机制研究

The interaction between water and rocks is a predominant factor for the deformation of slope rock mass induced by reservoir impoundment and the generation of major engineering disasters. The non-linear hydraulic coupling characteristics and evolution mechanism of fractured rock mass under water-rock effect cannot be fully obtained due to the restrictions of testing methods. This project plans to focus on the major hydropower plants, including Xiluodu, Laxiwa, etc., carry out studies based on the multiscale testing methods for the hydraulic coupling effect of fractured rock mass under high seepage pressure conditions and the hydraulic coupling analysis involving continuous-discontinuous medium mechanics, conduct hydraulic coupling mechanical tests of different scales through laboratory tests on rock cores, field tri-axial tests on rock masses, and shear tests on structural planes, reveal the non-linear hydraulic coupling characteristics and their evolution laws for fractured rock masses and structural planes under high seepage pressure. Based on the concept of continuous-discontinuous coupling analysis, this project plans to establish discontinuous deformation failure analysis theory covering different scales, study the mesoscopic mechanism that controls the evolution of macroscopic characteristics of rocks through macro-mesoscopic numerical tests method, reveals the relationship between the time-dependent evolution characteristics of mesoscopic structures and their macroscopic parameters. Combining multiscale mechanical test and meso-macroscopic numerical test results, this project plans to reveal the time-dependent degradation mechanism of the mechanical properties of fractured rock masses under water-rock coupling effect so as to provide reliable support for the prediction and prevention of major engineering geological disasters for the water conservancy project group in China.

水岩相互作用是水库蓄水诱发岸坡岩体变形、孕育重大工程灾害的主导因素；然而囿于试验方法的限制，无法获得全面反映水岩作用下裂隙岩体的非线性水力耦合特性及其演化机制。本项目拟以溪洛渡、拉西瓦等重大水电工程为依托，基于高渗压条件下裂隙岩体水力耦合特性的多尺度试验方法和基于连续-非连续介质力学的水力耦合分析方法的研究与构建，系统开展室内岩芯、现场岩体三轴与结构面剪切等不同尺度条件下的水力耦合力学试验，揭示高渗压下裂隙岩体和结构面的非线性水力耦合特性及其演化规律；基于连续-非连续分析耦合的思想，建立跨尺度的非连续变形破坏分析理论；通过宏细观数值试验研究主导岩石宏观特性演化的细观力学机制，揭示细观结构的时效演化特征与宏观参量的相关关系；综合多尺度力学试验和细宏观数值试验的研究成果，揭示水岩耦合效应下裂隙岩体力学特性的时效劣化机制，为我国水利枢纽群重大工程地质灾害预测与防治提供科学支撑。

水岩相互作用是水库蓄水诱发岸坡岩体变形、孕育重大工程灾害的主导因素，为了获得全面反映水岩作用下裂隙岩体的非线性水力耦合特性及其演化机制。本项目以溪洛渡、拉西瓦等重大水电工程为依托，通过多尺度水力耦合试验、连续-非连续水力耦合理论分析，揭示水岩耦合效应下裂隙岩体力学特性的时效劣化机制。项目主要成果包括：研制了带水压条件下的岩石干湿循环试验设备，并开展了水压环境干湿循环岩石劣化特性试验，提出了基于weibul分布的损伤本构模型；系统开展岩石水力耦合室内三轴试验，揭示了典型裂隙型、孔隙型岩石的水力耦合损伤特性；研制了现场大型水力耦合试验装备，首次开展了多种水力加载路径的现场大尺寸岩体真三轴、结构面剪切试验，充分研究了水力耦合条件下岩体的变形、破坏特征及层间错动带孔隙水压作用下变形时效特征，基于试验结果与理论分析提出了水力耦合作用下裂隙岩体变形参数劣化模型和层间错动带水压条件下的Burgers蠕变模型参数；基于最小势能原理，推导了考虑块体表面水压作用的DDA子矩阵，实现了连续-非连续的DDA水力耦合数值方法，完成了溪渡谷幅变形机制非连续变形数值分析。以上新型水力耦合试验装备的研制及综合多尺度力学试验和细宏观数值试验的研究成果，为高渗压条件下多尺度裂隙岩体的渗流-应力耦合特性研究提供了参考，为我国水利枢纽群重大工程地质灾害预测与防治提供科学支撑。