Freezing Shear Characteristics and Failure Mechanism of Rock Joints with Different Opening Degrees and JRC

Abstract On the basis of the rock‐coupled joints of Jiangluling Tunnel on the G214 line in the permafrost region of Qinghai, a freeze‐shear test was carried out to study the shear characteristics and failure mechanism of the jointed rock with different opening conditions. Given the 3D shape parameters of the joint surface the frozen shearing characteristics of the joint surface and its failure mechanism were revealed building on the theory of adhesion between the joints and the ice layer. Results showed that shear failure of frozen joints comprised four stages, compaction, sustained deformation, yielding and post‐peak stage. As the tension grows from 7 mm to 13 mm, the reduction in peak shear stress at different pressures for each specimen ranges from 43% to 81%, and the reduction in cohesion is 79‐98%. The angle of internal friction has no significant pattern with tension and roughness. Tests with different degrees of tension showed three different modes of shear damage at different pressures.