Abstract
The fluid flow in rock fractures during shear processes has been an important issue in rock mechanics. During shearing, because of the stiffer rock matrix, most deformation occurs in the joints, in the form of normal and shear displacement. Since the joints are rough, deformations will also change the joint aperture and fluid flow. In this article, the hydraulic apertures of the joints of dolomitic limestone foundation of Behesht Abad dam are investigated. Firstly, geological data during a site investigation phase in dam site is gathered, and then related calculations are done and the hydraulic conductivity of the joints is evaluated. The results indicate that the hydraulic conductivity of the joints is reasonable.
Highlights
The fluid flow in a rock mass is usually governed by three factors: the fluid properties, the void geometry and the fluid pressure at the joint boundary
The void geometry, i.e. the geometry of the volume between the joint surfaces, is governed by the geological history and can be described by several geometrical parameters, as aperture, frequency distribution, spatial correlation and contact area. These geometrical parameters are related in various ways to the joint void geometry
For fluid flow through rock joints, it is common to consider the joint as composed of two smooth parallel plates and the flow to be steady, single phase, laminar and incompressible
Summary
The fluid flow in a rock mass is usually governed by three factors: the fluid properties, the void geometry and the fluid pressure at the joint boundary. For fluid flow through rock joints, it is common to consider the joint as composed of two smooth parallel plates and the flow to be steady, single phase, laminar and incompressible Under these conditions, the hydraulic joint conductivity (Kj) may be written: kj. The hydraulic joint conductivity is a parameter expressing the flow through the joint under the influence of frictional losses, tortuosity and channeling These factors depend on the geometry of the flow channels and the fluid viscosity. When Darcy’s law is applied to natural rock joints with rough surfaces, many researchers suggests that a correction factor has to be used, which accounts for deviations from the ideal conditions assumed in the parallel smooth plate theory. Results by Hakami (1995) showed that the ratio between mechanical mean aperture (E) and hydraulic aperture (e) was 1.1 - 1.7 for joints with a mean aperture of 100 - 500 μm [4]
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