Shear creep behavior of red sandstone after freeze-thaw cycles considering different temperature ranges

摘要

A strong freeze-thaw (F-T) weathering effect influences the strength of rock in the high-altitude areas of the Qinghai-Tibet Plateau. To study the long-term deterioration characteristics of rock in an alpine F-T environment, shear creep experiments were conducted on red sandstone from the Sichuan-Tibet highway to analyze its shear creep characteristics under different temperature ranges. The results show that the rock's stress level gradually decreases with increasing temperature under the same number of F-T cycles, while the creep displacement gradually increases. The long-term strength and long-term reduction factor present apparent decreasing trends with an increase in the F-T temperature range. The failure morphology evolves from shear failure with a single horizontal plane to that with multiple dipping shear planes. The greater the temperature range is, the greater the number of shear secondary cracks that intersect, resulting in more complicated failure morphologies. Then, a Burgers model considering F-T and time-dependent damage was established. The parameters of this model were identified via the experimental creep data of the red sandstone. The accuracy and applicability of the model were verified by comparing the experimental and model-predicted results. These results are significant for the construction of major engineering projects in the alpine region.