Abstract
Hydromechanical coupling in rock masses is an important issue for many rock mechanics and hydrogeology applications. The change of a water-bearing state will induce the fracture of the intact rocks and further accelerate the shear slip instability of the sheared surface. To investigate the weakening effect of water content on the mechanical properties of a rock mass, laboratory direct shear tests combined with three-dimensional analysis of sheared surfaces were carried out on sandstone samples with different water contents. The variogram parameters, sill and range, were applied to quantify the morphology of shear fracture surfaces, to reflect the shear failure process of the intact rock, and to provide a basis for resliding instability of jointed rock. It was determined that the sill represents the height of the fluctuation body in the fracture surface and the range represents the single fluctuation body and may reflect the frequency of fluctuations. The test results revealed that the increase in water content had a clear weakening effect on the shear strength and deformation behavior of rock, especially under saturated conditions. Moreover, the distribution of water in the samples directly affected the crack initiation and propagation and characteristics of the fracture morphology.
Highlights
Hydromechanical coupling in rock masses is an important issue for many rock mechanics and hydrogeology applications [1,2,3,4,5,6,7]
Wang et al [39] proposed that based on the morphology of sheared fracture surfaces, the process of crack initiation and propagation during shear failures can be obtained and pointed that two parameters (C and a) in the variogram were effectively to quantify the anisotropy of fracture surfaces: the sill (C) can reflect the height of the fluctuation body in the fracture surface and the range (a) can reflect the single fluctuation body and its fluctuation frequency
Direct shear tests were carried out on sandstone to investigate the effect of water content on the shear failure mechanism of the rock and the anisotropy characteristics of the shear fracture surface
Summary
Hydromechanical coupling in rock masses is an important issue for many rock mechanics and hydrogeology applications [1,2,3,4,5,6,7]. In mining and civil engineering, the redistribution of the stress field during the excavation of tunnels and underground caverns leads to the initiation and propagation of cracks, which can cause dramatic changes in the permeability of a rock mass [8, 9]. It is very important in engineering practice to study the failure and instability mechanisms of rock masses under the hydromechanical coupling action of groundwater [10]. The hydromechanical coupling mechanisms still are poorly understood [18, 19]
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