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研究层理砂岩在两种含水状态(自由饱水与真空饱水)、不同冻融循环次数(0次、20次、40次、80次、120次)条件下的三轴卸荷力学特性.研究表明:砂岩的强度随着冻融循环次数的增加而降低,真空饱水组的劣化程度较自由饱水组剧烈,外观损伤破坏主要出现在岩样端部边缘和层理面附近.加载与残余变形阶段产生轴向应变;卸荷阶段,围压降低与变形增长具有良好的相关性,随着冻融次数增加,卸荷阶段应变量减少,冻融作用对卸荷效应更敏感.冻融次数对破坏模式的影响有一定规律但不显著,试样破坏以剪切破坏为主,但随着冻融次数的增加,张拉破坏有增强的趋势.
The uniaxial unloading mechanical properties of layered sandstone under two water conditions (free and full water and vacuum saturated water) and different freezing and thawing cycles (0, 20, 40, 80 and 120) were studied. The results show that the strength of sandstone decreases with the increase of the number of freeze-thaw cycles, and the degree of deterioration of the vacuum saturated water group is more severe than that of the free-saturated water group. The appearance damage and damage mainly appear near the edge of the rock sample and the bedding plane. During the unloading stage, the reduction of confining pressure has a good correlation with the deformation growth. With the increase of the number of freeze-thaw cycles, the strain amount during the unloading phase decreases and the freeze-thaw effect is more sensitive to the unloading effect. The number of times has a certain regularity but not significant influence on the failure mode. The failure of the specimen is dominated by shear failure. However, with the increase of the number of freeze-thaw cycles, the tensile failure tends to increase.