DOI: 10.3724/SP.J.1235.2012.00296

Journal of Rock Mechanics and Geotechnical Engineering 2012/2012:4 PP.296-311

Morphological and mechanical analysis of natural marble joints submitted to shear tests

In order to evaluate the influence of the surface morphology on the mechanical behavior of twelve natural marble joints, very accurate topography measurements of joint surfaces under constant normal load (CNL) conditions were performed before and after shear tests. The surface topography was carried out using a three-dimensional (3D) laser-scanning profilometer with a parallel grid at a regular interval of 500 μm. Each surface before shearing was reconstructed by geostatistical methods according to eight different directions. A quantitative description of surfaces was performed using global and directional statistical parameters. These parameters allow to determine the surface anisotropy and to divide the joints into three groups of similar morphology according to a given direction. Each sample of the same group is submitted to the same normal stress but to different shear rates ranging from 5 to 20 μm/s. The influences of normal stress and shear rate on the mechanical behavior of the discontinuities were investigated, as well as the influence of the sample morphology on its dilatancy behavior. The morphology data of upper and lower walls also permit to quantify the contact areas before testing. After the shear tests, sheared surfaces were scanned again and reconstructed according to the shearing direction. Based on the topography data of joint surfaces obtained before and after shearing, damage zones that occurred during shearing were located for both walls of each joint. These characterizations of joint surfaces contribute to a better understanding of the shearing behavior of natural discontinuities.

Key words:rock joints,morphological analysis,mechanical behavior,experimental device,roughness

ReleaseDate:2014-07-21 16:38:18