Time-dependent closure of a fracture with rough surfaces under constant normal stress

Effect of shear displacement on the hydraulic conductivity of a fracture

“…Note that t 2 is always the maximum among the principal shear stresses. For the mechanical properties of the fracture, we referred to the experimental results obtained for tensile fractures in Inada granite, measured in the laboratory [6,7,12], to be consistent with the flow simulation, in which we used the synthetic fractures that reproduced the geometrical characteristics of tensile fractures in Inada granite. The following formula was applied for the normal stress (s n ) versus closure (d n ) curve regardless of the shear displacement [38]:…”

“…Thus, many experimental and analytical studies have focused on the hydro-mechanical properties of fractures [1,2], and previous studies have revealed several major points. As for the mechanical properties of a fracture, it has been shown that the normal stress versus closure curve of a fracture is highly non-linear, and this non-linearity increases with a decrease in the matedness of the fracture [3][4][5][6][7][8]; the shear stiffness increases with normal stress [9][10][11][12]; the dilation angle decreases with shear displacement due to the breakage of asperities during shear; and shear dilation is suppressed by an increase in normal stress until contraction eventually occurs under large normal stresses [9][10][11][12][13][14]. For the hydraulic properties of a fracture, it has been shown that the hydraulic conductivity of a sheared fracture is much greater than that of a normally closed fracture due to shear dilation [12][13][14][15][16][17]; the hydraulic aperture relative to the mean aperture is mainly governed by the mean aperture relative to the standard deviation (SD) of the initial aperture (the aperture of a fracture that is in contact at a single point) [18][19][20][21][22][23][24]; and a sheared fracture is hydraulically anisotropic, with a higher conductivity in the direction perpendicular to the shear displacement than parallel to the shear displacement [13,15,17,[24][25][26]…”

A fully-coupled hydrological–mechanical–chemical model for fracture sealing and preferential opening

“…(2) and (5) are assumed relations that represent the anticipated multi-mode response of the dissolution/precipitation process, driven by stresses. Many factors influence dissolution, such as stress, temperature, the pH value of circulated water, the physical properties of the fracture material, the geometrical distribution of the fracture surface, and timedependent closure of a fracture under constant normal stress [52]. Currently, there is no exact physical expression involving the influence of the above physical factors on dissolution, so the value of a, b and g are determined numerically.…”

A new constitutive law for the nonlinear normal deformation of rock joints under normal load

“…According to tribology, assuming that deformation of asperities of discontinuities under compressive load is linear-elastic, nonlinear characteristics of discontinuities under normal load can be reflected by the modification of the quantity and contact area of asperities. This kind of research was carried out by experts at home and abroad, including Swan, Sun Matsuki, Xia et al [13][14][15][16]. The model brought forward by Swan was effective only in smaller stress range, but unsuitable in overall range.…”