Characteristics and scale effect of joint roughness coefficient on failure planes of consequent bedding-parallel rock slopes
Journal
Journal of the Chinese Institute of Civil and Hydraulic Engineering
Journal Volume
28
Journal Issue
2
Pages
129-137
Date Issued
2016
Author(s)
Abstract
Roughness of sliding plane of dip-slope strata is one of the dominant factors determining the shear strength of rock mass, which is express by joint roughness coefficient (JRC) and measured by using Barton's combs generally. Although traditional methods are useful in laboratory scale, they are not well applicable in situ in large scale. However, the method is not easily used in situ by large-scale. The large-scaled Zhong-zhi landslides in Wulai Dist., New Taipei City, in northern Taiwan are chosen as study objects to be discussed scale effect and anisotropy of JRC. In order to evaluate the above-mentioned effects, different base-line lengths measuring the roughness from the sliding plan morphology in terms of photogrammetry by unmanned aerial vehicle (UAV) after the landslides took place. The JRC can be calculated quantitatively by the photogrammetry, which is applicable for rock slope in different scale. The photogrammetry canbe applied in large scale in the future. The sliding plane of dip-slope from top to toe is defined as active, transitional, and resistive zones. The sliding plane in the active zone is composed of bedding plane and steep-angled tension cracks, so the JRC at forward-slope (down-dip) direction is smaller than that at reverseslope direction. The sliding plane in the resistive zone consists of low-angled shear planes and the bedding plane, so the JRC at the down-dip direction is larger than that at the ascending direction. The study demonstrates the photogrammetry is applicable to calculate the JRC of large-scale rock slope, and extends the applicability of scale effect analysis. Besides, an anisotropic roughness model of rock slope with complex-stepped failure mechanism can be established as well.
Type
journal article