Characterization of rock joint surface anisotropy considering the contribution ratios of undulations in different directions

Abstract

Anisotropy in rock joint is strongly dependent on undulating surface morphology. Recent research of the morphology showed the parameter can express the different types of anisotropic characteristics of the joint surface separately. This report aims to analyze the common characteristic of the anisotropic distribution and exhibit the anisotropic variation trend. The joint morphology function consists of two morphology functions of regular plane in orthogonal directions, and the anisotropic variation determined by the contribution ratios of the two morphology. The roughness weight ratio in orthogonal direction of joint surface is used as an index to describe the anisotropic variation behavior, which proposes the anisotropic variation coefficient (AVC). On this basis, it is divided into 5 levels from strong anisotropic to isotropic. According to the assumption of anisotropic arc distribution, the anisotropic analytic function is derived and the agreement between the deduced curves and measured data therefore suggests the possibility of defining the morphology anisotropy through the index AVC. Finally, we verify the characteristic of three natural rock joints, and prove the proposed function can reflect the anisotropic distribution trend. The new index can be used to describe the anisotropic variation behaviour of rock joint surfaces.

Experimental study on anisotropic unloading mechanical behavior of bedded sandstone

“…Many scholars investigated the anisotropic mechanical properties of bedded rock through uniaxial or triaxial compression tests. The uniaxial compression strength tests of rocks at different bedding angles exhibited anisotropic strength and elastic properties 1 – 5 . The loading angle (The angle between the loading direction and the weak bedding plane) and confining pressure govern the Young’s modulus and the tensile strength of bedded sandstone 6 – 10 .…”

Determination of roughness coefficient in 3D digital representations of rocks

“…In this sense, the areas that present these properties are the fractures (joints), defined by the relationship between two rock surfaces separated at some points but in contact at others 2 , 3 . The anisotropic morphology of natural rock mass joints constantly affects their shear behavior 4 , 5 .…”

“…Some surface properties of these fractures are significant for their mechanical, hydraulic, thermal, and transport behavior, and the fluid flow in these places is superior to in the rock matrix 6 . One of these properties is the roughness, which is crucial in the stability of rock masses, and essential in geotechnical studies or engineering works 5 , 7 – 10 .…”

Characterizing Curvature and Roughness of Hard Bedded Glacial Forefields

“…Glacial slip along its bed may be thought of as analogous to fault slip where the glacier-bed interface approximates a fault, where whether a surface will be dominated by polish or striae is defined by the pattern of asperities in the slipping portion of the interface (the glacier) Fischer & Clark, 1997). Here, it is helpful to compute roughness both in terms of this model of slip and additionally in terms of joint surface roughness, given that quarrying exposes a pre-existing and/or created joint surface with its own characteristic roughness (Brown & Scholz, 1985;Zhang et al, 2014;Nigon et al, 2017;Huang et al, 2020). Along an ideal abraded surface, roughness would be expected to be perfectly anisotropic -that is, with angles of minimum and maximum roughness separated by 90 o -essentially similar to an artificially constructed anisotropically rough surface (see Huang, 2020, for such a wavy surface, and Hansen et al, 2023 for a DEM of representative striae) .…”

“…Here, it is helpful to compute roughness both in terms of this model of slip and additionally in terms of joint surface roughness, given that quarrying exposes a pre-existing and/or created joint surface with its own characteristic roughness (Brown & Scholz, 1985;Zhang et al, 2014;Nigon et al, 2017;Huang et al, 2020). Along an ideal abraded surface, roughness would be expected to be perfectly anisotropic -that is, with angles of minimum and maximum roughness separated by 90 o -essentially similar to an artificially constructed anisotropically rough surface (see Huang, 2020, for such a wavy surface, and Hansen et al, 2023 for a DEM of representative striae) . An ideal polished surface should be perfectly isotropic.…”