温度循环条件下粉土质砂的物理力学特征研究

Physical and mechanical characteristics of silty sand under temperature cycling conditions

为研究夏季极端高温天气对粉土质砂物理力学性质的影响,以重庆市某边坡土体为研究对象,通过室内试验模拟分析在夏季高温条件下日间暴晒,土温升高;夜间冷却,土温降低的循环过程对粉土质砂的力学特征的影响。试验结果表明:经过多次温度循环作用土样的含水率与密度不断下降;土样内聚力随温度循环次数升高;土样的内摩擦角基本保持稳定,不会随温度循环产生明显变化。当温度循环达到18次以后土样密度下降速度变快,而内聚力达到最大并开始保持稳定。在升温-冷却循环条件下土样抗剪强度增大,这主要是由内聚力增大所导致,因此内聚力是对温度循坏最为敏感的抗剪强度指标。试验结论为进一步研究温度循环对粘性土物理力学特征的影响和极端高温气候条件下的岩土工程设计施工提供重要参考。

Silty sand was taken from a Slope in Chongqing to study the effect of extreme high temperature in summer on its physical and mechanical properties. According to the indoor simulation test, the soil is warmed up by exposing to the daytime high temperature in summer and the cyclic temperature drop has an effect on the mechanical characteristics of the sand. The test has shown that, after repeated temperature cycling, the moisture and density of the sand were declining, the cohesion was rising with temperature cycles, and the internal friction angle remained stable. When the temperature cycling reached 18 times, the sand density became decreased quickly and the cohesive force reached the maximum and held steady. Under the heating-cooling cycle conditions, the shear strength increased with the cohesion. Thus, the cohesion is most sensitive to the temperature cycling. The resuhs have provided important references to further study of the effect of temperature cycling on the physical and mechanical characteristics of the cohesive sand and the design and construction of rock and soil engineering at