Evaluation method of rock damage under uniaxial compression based on unit series-parallel electrical conductive model

Abstract

The evaluation of rock damage behaviour is an important requirement for ensuring stability control and safety prediction in rock engineering. However, they have not been able to obtain sufficiently accurate and dynamic results due to the insufficient evaluation method. In this study, by means of fractals and unit series division, a unit series-parallel conductive model of damaged rock is derived, and a new evaluation method of rock damage under uniaxial compression was proposed. Rock was damaged by uniaxial compression, while electrical measurements and X-ray microscopy tests were performed to obtain the damaged rock resistivity, porosity, and fractal dimension variation. By establishing the relationship between defined meso-damage factor and resistivity, rock damage evolution law under axial compression was obtained. The results indicate that the growth trend was agree with the classical statistical damage model, which verified the accuracy of the results obtained by the proposed method. Moreover, as the strain increased, the damage factor determined by resistivity gradually decreased to −0.06 firstly and then increased rapidly to 0.79. Different from previous damage evolution law, brittle failure was observed and the cracks development in each stage was considered, including the closure (negative damage) and expansion (positive damage) of cracks.