短时冻融条件下残积土与冻融界面抗剪强度衰减规律对比分析

Attenuation Law of Shear Strength Between Residual Soil and Freeze-thaw Interface Under Short-term Frost Climate

为了分析短时冻融对浅层边坡稳定性造成的影响,揭示短时冻融条件下残积土和冻融界面抗剪强度损伤规律,通过盐水降低冰点实现冻融界面,进行不同冻融条件下快剪试验。试验结果表明:冻融主要损伤发生在前3次冻融循环过程中,含水率为21.5%时损伤最大,残积土和冻融界面的黏聚力损伤分别为41%和22%,内摩擦角为14%和10%,约占趋于稳定时的85%。黏聚力的损伤程度大于内摩擦角,且随含水率的增大而增大。冻融循环对残积土和冻融界面的强度及强度指标的影响差异随含水率增大、循环次数增加、冷端温度增大而增大。冻融作用对残积土的强度指标损伤程度均较冻融界面大,且强度指标均随着冻融次数增多呈指数衰减趋势。

Short-time freeze-thaw has certain effects on the stability of shallow slopes, in order to reveal the attenuation law of shear strength between residual soil and freeze-thaw interface under short-term freeze-thaw cycles, direct shear tests were carried out under different freeze-thaw conditions. The results show that damage degree of the shear strength parameters of residual soil is larger than that of freeze-thaw interface, and it decreases exponentially with the increase of freezing-thawing times. The main damage occurs during the first 3 times. When the moisture content is 21.5%. The cohesion damages of residual soil and freeze-thaw interface are 41% and 22% respectively, while the internal friction angle damages are 14% and 10%. The influence of freeze-thaw cycles on strength and strength parameters between residual soil and freeze-thaw interface increases with the increase of moisture content, cycles and cold end temperature. The freeze-thaw damage model of shear strength parameters was established and verified.