Investigation on jointed rock strength based on fractal theory

Abstract

Strength of discontinuities with complex structure is an important topic in rock engineering. A large number of studies have shown that fractal is applicable in the description of this discontinuity. Using fractal interpolation method for the generation of rock joints, numerical experiments of shear tests of the jointed rock mass model were carried out using FLAC^3D. The test results show that the real rock joints can be simulated by fractal curves obtained by fractal interpolation. The fractal dimension is an important factor for the characterization of jointed rock mass; test results show that the fractal dimension of rock joints can be related to the equivalent cohesion strength and shear strength of the rock mass. When the fractal dimension of the joint surface is less than critical dimension D_c 1.404, the cohesion strength and shear strength of the rock mass increase as the fractal dimension increases; for larger fractal dimensions, all mechanical parameters decrease as the fractal dimension increases. Joint surfaces with different degrees of roughness were obtained by the fractal interpolation method. Three types of failure modes were observed in the tests: climbing slip failure, climbing gnawing fracture, and non-climbing gnawing fracture.

Keywords

rock joints / fractal dimension / shear strength / numerical simulation

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