粗糙岩石节理剪切力学行为的细-宏观机制及尺度效应研究

The shear failure of rock joints has important effect on the strength and stability of jointed rock masses. Therefore, studies on the shear behavior of rock joints have significance to the stability controlling of jointed rock masses. In this project, a comprehensive method combining field investigation, laboratory test, theoretical analysis and numerical simulation is adopted to study the mesoscopic and macroscopic mechanism of rock joint shear behavior as well as its scale effect. The morphology of rock joints with laboratory scale and field scale will be studied, and a quantitative evaluation method of joint roughness considering anisotropy and scale effect will be established. A series of direct shear tests will be carried out on regular and rough joints to investigate the degradation of asperities and the characteristics of strength and deformability of joints. Based on test results, the mesoscopic and macroscopic mechanism of shear behavior will be in-depth revealed. In order to conduct numerical simulation on shear behavior of rock joints considering scale effect through Particle Flow Code (PFC2D/3D), the necessary mesoscopic parameters in PFC are firstly calibrated by macroscopic parameters obtained from direct shear tests on multi-scale joint samples carried at laboratory. Then numerical models will be built up to simulate the whole shear process of rock joints with size from laboratory scale to field scale. According to results from both laboratory tests and numerical simulations, the scale effect of shear behavior of rock joints is studied, and a theoretical model is proposed to estimate the shear strength of rock joints with multi-scale. This project will provide theoretical and technical support to the stability controlling of jointed rock masses.

岩石节理的剪切破坏是影响节理岩体强度与稳定的关键因素，深入研究节理的剪切力学行为对于控制节理岩体的失稳破坏具有重要意义。本项目采用现场调查、室内试验、理论分析和数值模拟相结合的方法，研究粗糙岩石节理的细观和宏观剪切力学行为及尺度效应。对室内小尺寸和现场大尺寸节理的表面形貌特征进行研究，提出考虑各向异性和尺度效应的粗糙度定量化表征方法；开展单一尺度的粗糙节理室内剪切试验，分析节理微凸体的细观损伤退化演化规律与宏观变形破坏特征，揭示节理剪切力学行为的细-宏观响应机制；通过室内不同尺寸节理直剪试验，采用试验所得的宏观力学参数对颗粒流细观计算参数进行标定，开展从室内小尺度到现场大尺度的多尺度节理数值试验，综合物理试验和数值试验成果，揭示节理剪切力学行为的尺度效应发生机制，建立多尺度粗糙岩石节理剪切强度力学模型。研究成果可以为节理岩体的稳定性分析提供理论依据和技术支撑。

岩石节理的剪切破坏是影响节理岩体稳定性的关键因素，开展节理剪切力学行为的研究对于岩体工程设计和灾害防治具有重要的理论和应用价值。本项目以岩石节理为研究对象，采用室内试验和理论分析相结合的方法，对节理的细-宏观剪切机制、节理形貌结构的定量评价、以及节理剪切强度模型开展研究。研究了节理凸起体的起伏度和倾角对节理损伤退化特征、破坏模式和剪切力学参数的影响，揭示了节理凸起体的四种典型破坏模式。基于黏结摩擦理论，在细观层次上建立了节理破坏模式随凸起体倾角变化的理论分析模型。通过开展粗糙节理的直剪试验，分析了节理形貌和法向应力对不同尺寸和不同剪切方向条件下节理的剪切强度、剪切刚度和剪切损伤分布特征的影响。揭示了不同尺寸和不同剪切方向条件下节理剪切损伤区域的分布规律及其随法向应力的演化特征。综合考虑节理形貌的几何特征和力学属性，将节理形貌分为非稳态和稳态结构，提出非稳态结构角来表征节理形貌的非稳态特征，建立粗糙度角模型来描述节理微凸体的分布情况，采用最大起伏度和粗糙度角共同描述节理的稳态形貌。对节理细-宏观形貌进行二维和三维定量评价，分析了形貌参数随节理尺寸的变化特征，并基于起伏度与粗糙度两类参数，建立了JRC的定量评价模型。考虑峰值剪胀角的演化特征和力学边界条件，推导出了负指数函数型的峰值剪胀角演化力学模型，建立了可考虑节理尺寸的峰值剪切强度预测模型。分析了基本摩擦、剪胀和剪断三个分量对节理峰值剪切强度的贡献，揭示了不同节理的各剪切强度分量随节理尺寸和法向应力的变化特征。