The Impact of Shear Rate on the Mechanical Behavior of Rock Joints Under Multiple-Influencing Factors

He L, Lu X, Copeland T, Chen J, Yan J, Zhao W (2023) The Impact of Shear Rate On the Mechanical Behavior of Rock Joints Under Multiple-Influencing Factors. Rock Mech Rock Eng 56(10): 7397-7414.

全文地址：The Impact of Shear Rate on the Mechanical Behavior of Rock Joints Under Multiple-Influencing Factors | Rock Mechanics and Rock Engineering (springer.com)

Abstract: The shear rate is an important factor that influences the shear mechanical properties of rock joints. In this paper, constant normal load (CNL) direct shear tests at different shear rates (vs= 0.2–5.0 mm/min) were performed on rock joint specimens to investigate the shear behavior and failure modes under various joint roughness coefficients (JRC = 6.071–17.212), joint wall compressive strengths (JCS = 9.36–25.86 MPa), and normal stresses (σn = 0.936–2.586 MPa). The experimental results indicated that the peak shear strength gradually decreased, the peak shear displacement increased and the residual shear strength decreased with increasing shear rate. The experimental findings suggested that with an increasing JRC and a decreasing JCS and σn, the peak shear strength and peak shear displacement were greatly influenced by the shear rate. Additionally, shear-off and wear failure modes were observed in this research and were both intensified by increasing shear rates. However, the failure mode tended to change from wear to shear-off as the shear rate increased, and this phenomenon was enhanced when JRC, JCS, and σn decreased. A modified new shear strength correlation model that related vs and valid values of JRC, JCS, and σn was developed to estimate the shear strength of rock joints. The predicted results indicated that the newly proposed model performed better than the existing models. Highlights The influence of the shear rate on the valid values of joint roughness coefficients, joint wall compressive strengths, and normal stresses was evaluated. The evolution of the mechanical behavior and failure modes of rock joints related to the shear rate was investigated. A shear strength correlation model that related to shear rate was proposed to estimate the shear strength of rock joints.