Determination of joint roughness coefficient (JRC) for slope stability analysis: a case study from the Gold Coast area, Australia

Abstract

Surface roughness of rock discontinuities is an important factor that determines the strength characteristics of rock mass. Joint roughness coefficient (JRC), which is typically measured by means of Barton's combs in the field, is widely used to describe the joint roughness. However, this traditional method of measurement can be rather subjective, labor-intensive and time consuming. In contrast, photogrammetry can provide an alternative method to obtain relatively simple and fast measurements of JRC based on high resolution 3D models. However, the reliability of such measurements still remains an issue as the results from photogrammetry can be affected by the quality of images. This study seeks to clarify whether photogrammetry can produce accurate measurements of JRC that can be used to assess the stability of slopes. A rock slope with a recent wedge failure in the Gold Coast area, Australia was selected for this purpose, and three different methods such as manual measurements, photogrammetry, and tilt tests were employed to determine the JRC. The obtained results showed some discrepancy in the values of JRC obtained from these three different measurements. In particular, the JRC obtained using the Barton's comb had slightly higher values compared to those determined through the photogrammetry method while the tilt test results tended to yield overestimated values of JRC. Computer analysis using UDEC was also performed to study the effect of JRC variation on the slope stability. It was found that an increase in the JRC led to an increase in the safety factor of the slope.

Assessment of the Accuracy of Close Distance Photogrammetric JRC Data

“…The target areas at site #6 were parts of sandstone rock blocks for landscaping which were individually oriented with different angles to the optical axes. Detailed geological conditions and strength properties for the sandstone and shale at the sites are presented in the previous literature by the authors (Kim et al 2013(Kim et al , 2015b.…”

Analysis of Fracture Roughness Control on Permeability Using SfM and Fluid Flow Simulations: Implications for Carbonate Reservoir Characterization

“…Another widely used methodology derives the hydraulic aperture from the mechanical aperture, E, and the joint roughness coefficient JRC as proposed by Barton et al [7]: e = E 2 JRC 2 5 , 4 where JRC is derived by comparing the fracture profile obtained with the Barton Comb with the standard tables provided by Barton and Choubey [8]. This methodology is perhaps the simplest and cheapest way to obtain fracture surface roughness values and has been widely used in outcrop studies [9][10][11][12][13]. The disadvantages of this method are related to the moderate resolution (about 1 mm) and the inaccuracy of equation (4) at relatively wide apertures (with respect to the JRC value).…”

“…Various approaches have been reported in the literature for mapping the surface of fractures and faults in the field or laboratory involving the use of Lidar [14,15], laboratory profilometers [16][17][18], and SfM photogrammetry (e.g., [12,19]). Corradetti et al [19] applied SfM photogrammetry for mapping fracture surfaces obtaining 3D reconstructions with point-cloud densities of equal quality to Lidar-derived data.…”

A New Fast and Low-Cost Photogrammetry Method for the Engineering Characterization of Rock Slopes

“…In this case, if the point cloud does not have a sufficiently high resolution, it may require a 3D model specifically obtained for roughness measurement. Similar approaches for the extraction of joint roughness from DP and/or LS have been documented by Haneberg [22], Poropat [23] and Kim et al [24].…”