The scanning tests were conducted on three groups of natural rock joints using the X3 3D laser scanner, in order to characterize the morphological characteristics of rough rock joint surface quantitatively. The joint surface was reconstructed based on the Delaunay triangulation, the relationship between the asperity and the shear direction was analyzed, and a new model was developed to characterize the relation between the effective dip angle and the potential contact area. Besides, the relationship between joint roughness and the sampling interval was investigated. Results show that the results of the new model has a good agreement with the morphological test result. In addition, the new model has better accuracy compared with Grasselli’s model. A new roughness index was proposed based on the proposed model, and the new index is compatible with dimensional analysis and can capture the anisotropic characteristics of joint roughness. The new index can be used to characterize the roughness of natural rock joints. In addition, it is found that the roughness index decreases as the sampling point distance increases. Under certain circumstances, the increase in the sampling point distance in a local area will cause the roughness to decrease, which is because the first-order roughness feature of the joint is exaggerated.
Xi CHEN,Ya-wu ZENG. Improved morphology characterization method and sampling effect of rough rock joint. Journal of ZheJiang University (Engineering Science), 2021, 55(11): 2161-2169.
Fig.1Three-dimensional scanner X3 and scanning process
Fig.2Morphology of rock joint surface
Fig.3Relationship between asperity and shear direction[24]
Fig.4Potential contact area corresponding to different critical effective angles
Fig.5Contact area ratio corresponding to different critical effective angles
Fig.6Flow chart of joint morphology calculation
Fig.7Fitting accuracy of each model in forward shear direction
Fig.8Fitting accuracy of each model in reverse shear direction
Fig.9Radar plot of shear direction
Fig.10Anisotropy of roughness
Fig.11Morphology characteristics of joint under different sampling intervals
Fig.12Variation of $\theta^*_{\rm{r}}$/k of each joint with shear direction and sampling interval
Fig.13Schematic diagram of roughness index increasing with sampling interval
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