Study on the contribution and influence of surface asperities of rock discontinuities on shear strength
To analyze the mechanical response of surface asperities under different shear stress conditions,the UDEC software was employed to simulate and analyze the mechanical behavior and wear characteristics of 17 groups of rock joints with various sawtooth asperities under varying normal stresses.The findings were validated through laboratory tests.The results show that the effects of the attached sawtooth number and the sawtooth height ratio on the peak shear strength of rock joints initially show a positive correlation,but the correlation weakens after reaching a certain level,and are also affected by normal stress conditions.The increase of normal stress will weaken the contribution of the attached sawtooth number and the sawtooth height ratio to the improvement of shear dilation of rock joints.The joint roughness coefficient(JRC)calculation method considering only the maximum undulating asperity is only applicable under low normal stress conditions.It is also observed that there are four main failure types in direct shear tests for the rock joints with various sawtooth asperities.By conducting response surface analysis,a JRC calculation model for the sawtooth rock joints was derived with an error of less than 10％compared to experimental results.This study reveals the mechanical responses of rock joints with various sawtooth asperities,providing a comparative reference for engineering practice and further exploration of using asperity amplitude in characterizing rock joint roughness.
rock mechanicssawtooth rock jointssurface asperitiesshear characteristicsjoint roughness coefficientnumerical simulation
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