Experimental and Numerical Studies on Mechanical Characteristics and Fracture Behaviours of Jointed Rock with Different Roughness

Abstract

As a feature of rock mass, joints exist widely and seriously affect the stability of rock mass engineering. The natural joint surface is mostly rough structure, further leading to more complicated mechanical characteristics such as strength and deformation of rock. In this paper, samples containing rough joints were prepared using three-dimensional printing technology and rock-like material pouring method. Uniaxial compression tests were carried out on rock-like samples with different joint roughness coefficients by the electro-hydraulic servo-controlled rock mechanics testing system to study the effect of joint surface roughness on strength, deformation and failure mode of samples. On this basis, a discrete element model with a rough joint surface was established based on particle flow code in two dimensions. The crack propagation characteristic of joint surface on the deformation and failure process of jointed rocks was studied. The fracture mechanism of rough jointed samples was explained from the microscopic perspective. The results showed that the sample's peak strength, peak strain, elastic modulus and secant modulus increased with the increase of joint roughness coefficient under uniaxial compression, and peak strength and elastic modulus were more sensitive to joint roughness. With the increase of joint roughness coefficient, the failure mode of the sample developed from shear failure to tensile-shear mixed failure and splitting failure. In addition, the strain with tensile cracks and shear cracks increased, and the number of tensile cracks increased with the increase of joint roughness coefficients, while the shear cracks decreased. The research results are of great significance for revealing mechanical characteristics and fracture behaviours of jointed rock with different roughness.