冻融循环作用对黄土力学性质损伤的试验研究
Experimental study on mechanics properties damage to the loess under the freeze-thaw cycle

通过对陕西杨凌Q3黄土进行不同初始含水量、不同低温温度及不同冻融循环次数条件下的静三轴剪切试验,揭示不同初始含水率、不同低温温度及不同冻融循环次数对黄土力学性质影响的过程与机理,基于极限平衡法建立冻融循环作用下强度参数的损伤模型。研究结果表明:黄土强度参数随冻融循环产生劣化,黄土的黏聚力c开始时冻融循环劣化效应强烈,在经过5~7次冻融循环后,黏聚力达到一个稳定值,当含水量很高时黏聚力下降不明显,内摩擦角φ随冻融循环次数无明显变化;建立的强度参数值随冻融循环次数增加的损伤模型能够很好地反映冻融循环作用下黄土抗剪强度的折减劣化规律,该损伤模型对冻融损伤作用下黄土地区的工程设计与施工具有指导和借鉴意义。
Based on freeze-thaw cycle test, the low temperature rebound test and the tri-axial shear test were conducted on Shaanxi Yangling Q3 loess under the replenishment conditions. Besides, the process and the mechanism of effects on mechanical properties of loess by initial water content and difference low temperature and freeze-thaw cycle was revealed, and the damage model of strength parameters is established under the effect of freeze-thaw cycle. The research shows that strength parameters of loess show signs of deterioration with the freeze-thaw cycle. The cohesion of loess has significant degradation effect at the beginning of the freeze-thaw cycle, and cohesive force reached a steady value after 5~7 times freeze-thaw cycle. Besides, cohesion of decline is not obvious when the moisture content is very high, and the change of angle of internal friction is not obvious with the freeze-thaw cycle. The values of strength parameter of the damage model can be well reflected by the increase of the number of freeze-thaw cycles and the shear strength of shear strength of loess under the action of freezing and thawing cycles, which can provide data for engineering design and construction in loess area from freeze-thaw damage