Effect of Cyclic Freezing-Thawing on the Shear Mechanical Characteristics of Nonpersistent Joints

Abstract

The effects of freezing-thawing cycles and persistency differences have a significant impact on the shear mechanical properties of joints. In this paper, a series of joints direct shear tests were performed on freezing-thawing treated joints to investigate the effect of freezing-thawing cycles and the persistency on the shear strength deterioration of joints. Shear strength and residual strength decrease with the freezing-thawing cycle increase and joint persistency increase. Shear strength damage mainly generates in the initial stage of the freezing-thawing cycle, and the shear strength decreases slightly in the late freezing-thawing cycle stage. The freeze-thaw cycle has a minimal effect on the shear strength of joints with low persistency, yet has a great effect on joints with high persistency. The damage of joint roughness caused by freezing-thawing cycles increases with joint persistency increases. When the joint persistency is constant, the shear strength parameter decreases with the freezing-thawing cycle at first and then tends to be stable. Cohesion is the dominant factor that controls shear strength. When freezing-thawing cycles are constant, the friction angle decreases slowly with persistency at first and then decreases rapidly, and the friction angle is the dominant factor that controls shear strength.

Anchor Stress and Deformation of the Bolted Joint under Shearing

“…Jiang et al [9] simulated series of direct shear tests on coplanar and noncoplanar jointed rocks using the PFC2D. e failure of joint will greatly affect the safety of rock mass [10][11][12][13][14]. Bolts are widely used in major projects such as steep slopes and tunnels as an important means of reinforcing the fractured rock masses [15][16][17][18].…”

Shear Resistance of Rock Joint under Nonuniform Normal Stress

“…Owing to nonlinearity of shear strength and nonuniform distribution of normal stress, it is impossible to make a simple linear superposition of the overall shear strength of joint with nonuniform normal stress [19]. For linear Mohr-Coulomb criteria, linear superposition is available for shear resistance calculation and is thus independent of normal stress distribution [38][39][40].…”

Improved Nonlinear Nishihara Shear Creep Model with Variable Parameters for Rock-Like Materials

“…Research on rock characteristics under direct shear creep conditions is relatively scarce. e primary failure mode of rocks under natural conditions is shear failure [24][25][26][27][28][29][30]. erefore, the shear creep failure behavior of rocks should be studied.…”