Numerical study of strength, deformation, and damage characteristics of marble under true triaxial compression

Abstract:

A discrete element particle flow procedure was adopted to investigate the mechanical behaviour of rock under true triaxial conditions. The deformation and damage processes, the intrinsic connection between microcrack growth and evolution, and the intermediate principal stress effects in marble specimens were analyzed under different stress paths. Results show that the parallel bond model could accurately reflect the mechanical properties and damage modes of marble under true triaxial compression. The effects of intermediate principal stress on the peak strength, elastic modulus, failure angle, and failure mode evolution were significant. The octahedral theory could well fit the failure stress of the marble under true triaxial compression, and the obtained failure strength envelope had obvious linear characteristics. On the basis of the stress-strain curve, the crack expansion during the compression was divided into four stages: linear elastic stage, crack stable expansion stage, crack unstable expansion stage, and post-peak damage stage. With the increase in the intermediate principal stress, the brittle failure characteristics of the post-peak section of the stress-strain curve became stronger. The failure modes of the rock specimen changed from tensile failure to mixed tensile-shear failure, and the intermediate principal strain changed from tensile to compression. The evolution of rock damage showed a spoon-shaped trend as the intermediate principal stress changed.