Study on damage evolution and constitutive model of sandstone under the coupled effects of wetting-drying cycles and cyclic loading

Effect of the upper limit stress on the fatigue properties and crack propagation processes of sandstones containing pre‐existing crack under fatigue‐creep interaction

“…In the meso-structure of the rock mass, dislocation slip movement and pressure dissolution of crystal grains appear, which causes an increase in the number of fatigue cracks and an increase in fracture roughness. In addition, in terms of the failure mode, as the CSL increases, the brittleness of the rock mass is weakened, and the brittle failure is converted to a ductile failure, which is consistent with the results given by Shi et al 30…”

“…It can be seen from the figure that in the same cycle, the deformation damage of the rock sample increases with increasing CSL. Under the action of different CSL, the deformation damage of the rock shows a nonlinear cumulative increase with the increase in the number of loading and unloading cycles, which is consistent with the results presented by Shi et al 30 In the 15th-16th cycles, due to the creep load, the residual strain of the rock increases, which causes a significant increase in the deformation damage of the rock. In addition, during the whole test, the growth rate of rock deformation damage also increases with increasing CSL.…”

“…The failure modes of the rock mass under the interaction of fatigue-creep are all tensile-shear composite failures. At the same time, as the CSL increases, the surface of the sample can produce greater deformation before failure, the brittleness at failure is weakened, and the failure mode gradually changes from brittleness to ductility, which is consistent with the experimental phenomenon of Shi et al 30 and Wang et al 32…”

“…Han et al 29 established a rock salt cyclic creep correction model considering the three cyclic parameters of average stress, half amplitude, and cycle period. Shi et al 30 studied the damage mechanism of sandstone under the combined action of dry-wet cycles and fatigue loads and established a constitutive model of the rock mass. In terms of fatigue-creep interaction, affected by the heterogeneity and anisotropy of rocks, the existing research mainly focuses on isotropic materials such as metals and asphalt, and there are few related studies on brittle materials such as rocks.…”

Crack evolution law and failure mode of red sandstone under fatigue–creep interaction

“…[9][10][11] Wang et al 12,13 analyzed the crack propagation characteristics and failure modes of rock under multi-stage cyclic loading. Lin et al 14 and Shi et al 15 established a fatigue damage constitutive model of rock from a damage perspective. Cyclic loading and unloading parameters (waveform, amplitude, frequency, and upper and lower stress limits) have important effects on the deformation, mechanical properties and energy evolution of rock.…”