Pre-Peak Deformation And Damage Features Of Sandstone Under Cyclic Loading

In this paper, several sandstone specimens are prepared and subjected to uniaxial compression and cyclic loading. For each specimen, the loading segment of the stress-strain curve was fitted, and the peak slope of this segment was taken as the elastic modulus of the specimen in that cycle. It is learned that, under cyclic loading, the elastic modulus of each specimen increased with the growing number of load cycles, and tended to be stable; meanwhile, strain hardening was observed on all specimens. Moreover, the specimens are similar in corresponding stress, although varied in corresponding strain. In the same cycle, the tangent modulus of the loading phase was smaller than that of the unloading phase under the same stress. Finally, the damage variables of sandstone specimens under cyclic loading were defined from the angle of energy, revealing that the damage variables had logarithmic growth with the load cycles in the later stage.