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| Dynamic impact compression characteristics and damage mechanism of freeze-thaw sandstones with different saturation levels |
| JIA Peng，LU Jialiang，MAO Songze，GUO Ziming，WANG Yin |
| (School of Resources and Civil Engineering，Northeastern University，Shenyang 110819，China) |
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Abstract In order to study the effect of saturation on the dynamic impact compression characteristics of freeze-thawed sandstone，red sandstone samples with saturation of 0%，25%，50%，75% and 100% were subjected to dynamic impact compression tests after 0，25 and 50 freeze-thaw cycles，respectively. The results show that，at the same number of freeze-thaw cycles，the dynamic mechanical properties of the rock samples deteriorate with the increase in saturation. When the saturation is the same，the dynamic mechanical properties of the rock samples deteriorate with the increase in freeze-thaw cycles，showing a decrease in peak strength and an increase in peak strain and fractal dimensions. The effect of saturation on the dynamic mechanical properties of freeze-thaw rock samples is higher than that of the number of freeze-thaw cycles. When the saturation degree is lower than 25%，the increase in the number of freeze-thaw cycles has less deterioration on the dynamic mechanical properties of the rock sample; when the saturation degree is greater than 25%，the freeze-thaw damage inside the rock sample gradually accumulates with the increase in the number of freeze-thaw cycles，and the dynamic mechanical properties deteriorate more significantly with the higher saturation degree. As the saturation increases，the damage inside the freeze-thawed rock sample increases，pores，intergranular and intragranular cracks appear，leading to the increase in the fragmentation of the rock sample under impact loading，and the decrease in energy utilization under the impact load.
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