随机形貌岩石节理剪切数值模拟和非线性剪胀模型

 采用满足正态分布的随机函数，构造岩石节理剖面的形貌，为研究受剪岩石节理的细观剪切特性和宏观剪胀效应提供研究基础。利用UDEC软件，基于CY微段节理模型，开发随机形貌岩石节理直剪特性的数值分析程序，采用CY微段节理模型的细观剪切力学参数，探讨微段节理的细观剪切特性和岩石节理的宏观剪切响应，提出节理抗剪强度参数与节理面粗糙度系数JRC之间的拟合关系。得到如下结论：JRC越大，岩石节理的宏观剪切峰值强度和剪胀角随之增大，而峰值剪切位移与JRC成反变化关系；随着法向应力的增加，节理的剪胀效应逐渐减弱；这些数值结论得到模型实验的充分验证。微段节理的细观切向爬坡和剪胀效应是岩石节理产生宏观剪胀的细观力学机制。通过对随机形貌岩石节理的宏观剪胀数值曲线性态进行分析，提出能考虑节理粗糙度JRC和法向应力影响的非线性剪胀本构模型，该模型较好描述了受剪岩石节理的剪缩段和剪胀段。

SHEAR NUMERICAL SIMULATION OF RANDOM MORPHOLOGY ROCK JOINT AND NONLINEAR SHEAR DILATANCY MODEL

Using random function obeying normal distribution to construct rock joint profile morphology， a kind of simulation method of rock joint profile provides the search foundation for microscopic shear characteristics of rock joint and the effects of macroscopical shear dilatation. Using UDEC software，based on improved CY joint model，a numerical analysis program for direct shear characteristics of random morphology rock joint was developed. Microscopic shear characteristics of micro-segment joint and macroscopic shear response of rock joint are discussed by using microscopic shear mechanical parameters of CY micro-segement joint model. The fitting relationships between joint shear strength parameters and joint roughness coefficient(JRC) are proposed. As the results，the greater the JRC is，the greater the peak shear strength and dilatancy angle of rock joints are. But the peak shear displacement is inversely related to JRC. With the increase of the normal stress，the dilatancy effect of joint is gradually weakened；these simulation results have been fully verified by modeling experiment. The microscopic tangential climbing and dilatancy effect of micro-segment joint are the meso-scopic mechanical mechanism of macroscopic shear dilatation of rock joints. Through the analysis of macroscopic shear dilatation numerical curves of random morphology rock joints，a nonlinear shear dilation constitutive model considering the effect of JRC and normal stress is proposed；the model can well describe shearing shrinkage and the shear dilatation during shearing process of rock joint.