Abstract 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.
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Received: 17 September 2012
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