Definition Of Discontinuity In Rock Engineering

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In the rock engineering fields dealing with the excavation of rock masses such as quarrying, surface mining, the term" discontinuity" is a widely used collectively term. A discontinuity is a plane that marks a change in physical or chemical characteristics in a soil or rock mass and has the zero or low tensile strength. It can be in the form of geological structures such as joints, bedding planes, faults, fractures, fissures, crack etc. The ISRM (1978) refers to the use of ten parameters for the characterization of discontinuities and these include three geometric parameters: spacing, persistence, and orientation. Each of these ten parameters has a significant influence on the rock properties. However, three geometric parameters in particular,…show more content…
The mapping methods developed can be grouped into two types. One is by direct methods and another is by indirect methods. In the indirect method, initially, measurement of physical properties of the rock mass such as the seismic velocity and the discontinuity parameters are estimated from the physical parameters (Grainger et al., 1973). The direct method uses the visual measurement of each discontinuity. Such measurements of lengths and angles are made directly on rock outcrops, bench faces, boreholes (Piteau, 1970; ISRM, 1978) as well as from photographs of rock exposures (Franklin & Maerz, 1988; Farmer et al., 1991). The direct measurement of rock exposures can be carried out using line mapping techniques. Line mapping often referred to as the Scanline technique is widely used…show more content…
In the modeling of discontinuity geometry, delineation of discontinuity sets is a first step in creating discontinuity geometry patterns (Dershowitz & Einstein, 1988). Discontinuities in rock masses are not uniformly distributed in all directions but are often formed in sets (Piteau, 1970; Pollard & Yaddin, 1988). There are several analytical functions available to describe the discontinuity orientation distribution, such as the Fisher and the Bingham distributions (Baecher, 1983; Dershowitz & Einstein, 1988; Priest,

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