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浙江大学学报(工学版)
Journal of ZheJiang University (Engineering Science)  2021, Vol. 55 Issue (11): 2161-2169    DOI: 10.3785/j.issn.1008-973X.2021.11.017
    
Improved morphology characterization method and sampling effect of rough rock joint
Xi CHEN(),Ya-wu ZENG*()
School of Civil Engineering, Wuhan University, Wuhan 430071, China
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Abstract  

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.

Key words： rock joint      three-dimensional roughness      effective dip angle      potential contact area ratio      sampling effect     
Received: 09 September 2020      Published: 05 November 2021
CLC:  TU 45  
Fund:  国家自然科学基金资助项目(41772308)
Corresponding Authors: Ya-wu ZENG     E-mail: 1780164218@qq.com;zengyw@whu.edu.cn
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Xi CHEN
Ya-wu ZENG
Cite this article:

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.

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https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2021.11.017     OR     https://www.zjujournals.com/eng/Y2021/V55/I11/2161


粗糙节理的改进形貌表征方法及采样点距效应

为了定量表征粗糙岩石节理的三维形貌特征，采用三维工业扫描仪X3对3组天然红砂岩节理进行三维激光扫描试验. 基于Delaunay点云离散算法重构岩石节理面，分析单个微单元体与剪切方向的几何关系，提出改进模型来描述潜在接触部分随表面有效倾角门槛值的变化特征，并研究节理粗糙度随采样点距的变化规律. 结果表明：改进模型与试验结果较吻合，精度优于传统的Grasselli模型. 基于改进模型提出新的粗糙度评估参数，该指标满足量纲分析的要求，能准确捕捉节理粗糙度的各向异性特征，可以用于表征天然岩石节理的粗糙度. 发现节理形貌表征存在采样点距效应. 随着采样点距的增大，节理粗糙度不断减小. 在特殊情形下，采样点距增大会导致粗糙度增大，主要是因为放大了节理的一阶粗糙度特征.


关键词： 岩石节理,  三维粗糙度,  有效倾角,  潜在接触面积比,  采样点距效应 
Fig.1 Three-dimensional scanner X3 and scanning process
Fig.2 Morphology of rock joint surface
Fig.3 Relationship between asperity and shear direction[24]
Fig.4 Potential contact area corresponding to different critical effective angles
Fig.5 Contact area ratio corresponding to different critical effective angles
Fig.6 Flow chart of joint morphology calculation
Fig.7 Fitting accuracy of each model in forward shear direction
Fig.8 Fitting accuracy of each model in reverse shear direction
Fig.9 Radar plot of shear direction
Fig.10 Anisotropy of roughness
Fig.11 Morphology characteristics of joint under different sampling intervals
Fig.12 Variation of $\theta^*_{\rm{r}}$/k of each joint with shear direction and sampling interval
Fig.13 Schematic diagram of roughness index increasing with sampling interval
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