Effects of cyclic fatigue loads on surface topography evolution and hydro-mechanical properties in natural and artificial fracture

Abstract

This work investigated permeability evolution for fluid flow through natural fractures and artificial fractures in granite and the evolution of failure surface under cyclic fatigue loads condition. We revealed and compared a clear distinction between two types of fracture surfaces before and after the test, and analyzed the evolution of fracture surface roughness and other parameters which can characterize their topography feature, as well as the relationship between fracture surface topography and permeability. The studies indicated that artificial fractures show the higher roughness and subtler variations of surface topography than those of natural fractures, however, the surface topography of natural fractures was more susceptible to cyclic fatigue loads. The initial permeability and average permeability of nature fractures were both higher than those of artificial fractures during the stress-seepage coupling test and the permeability of artificially fracture was more sensitive to normal stress changes. Moreover, the experimental results were in line with theoretical predictions and the research results can provide reference for preventing the failure of rock engineering.