Influence of intermediate principal stress on the mechanical properties of rocks containing fractures Available to Purchase

The excavation fracture zones develop during the staged excavation of caverns and tunnels, which still have bearing capacity. However, further excavation and support activities will change the stress state in these areas until these activities cease. The influence of intermediate principal stress, σ₂, on the strength and deformation characteristics of the surrounding rocks is not clear. In this paper, multi-step true triaxial tests are carried out on rock specimens containing stress-induced fractures to investigate the influence of σ₂ on the mechanical properties of these specimens. The experimental results show that Young's modulus decreases with decreasing σ₂, while the ratios of deformation in the two lateral directions increase. However, due to the fractures induced by true triaxial stress parallel to σ₂, this fractured rock strength is not influenced by σ₂, so a strength criterion that does not consider σ₂ effect should be adopted in this failure pattern. This study deepens the understanding of the deformation and the bearing capacity of surrounding rocks.