Mechanical properties of freeze-thaw and damage propagation law for rock

摘要

Using the experimental research method of ‘the temperature gradient under the open system’ recommended by the International Association of Ground Freezing, the freeze-thaw cycling and mechanical experiment were conducted for two types of rock which are red sandstone and shale in water-saturated state, the influence of the lithology and freeze-thaw cycle on rock mechanical characteristics were studied systematically. The unified damage propagation constitutive relation and damage evolution equation of the freeze-thaw and loaded rock under different free-thaw cycles were established by applying the mechanics of freeze-thaw media and damage. The damage evolutionary route of meso-structure and the macro mechanical behavior of rock materials were described. The result shows that three deterioration modes of freeze-thaw damage are spalling mode, fracture mode and crack mode. Sandstone is more sensitive to the freeze-thaw cycle and its freeze-thaw damage is more serious than shale. The initial microscopic differences within the materials determine the characteristics of damage propagation, showing the macroscopic differences in the final state. The freeze-thaw and loaded damage characteristics predicted by damage model are in good agreement with the freeze-thaw mechanical experiment. The impact of the freeze-thaw and loaded damage must be considered in rock engineering design and construction in cold regions.