基于试验的多年冻土典型路基形变研究

Deformation of a Typical Embankment in Permafrost Regions Based on Experiments

多年冻土塑性形变特性是理解其应力响应性态及过载退化的关键,也是近年来冻土工程和岩土工程学科研究领域的热点问题。基于三轴试验测得9%、12%和15%含水量条件下-1℃、-2℃多年冻土弹性模量、黏聚力和内摩擦角等土层物理力学参数,建立典型铁路路基模型,分析天然地震荷载作用下多年冻土区铁路路基在温度升高、强度退化作用下的塑性形变规律。结果表明:随着温度升高冻土强度退化,-1℃的塑性形变大于-2℃各坡脚、路基中心处的塑性形变;左右坡脚处塑性形变具有对称性分布规律;典型铁路路基试验土层地温由-2℃升高到-1℃,9%含水量试验土层塑性应变左坡脚放大3.5倍、右坡脚放大4.9倍,12%含水量试验土层塑性应变左坡脚放大1.6倍、右坡脚放大2.5倍。多年冻土退化条件下12%含水量的试验土层表现出良好的稳定性,在同等受力条件下塑性变形增长最小。

The plastic deformation characteristics of permafrost are the key to understand the stress response state and the degradation of overload.The topic is also an active research area in the field of permafrost engineering and geotechnical engineering in recent years.Based on a triaxial test,the physico-mechanical parameters of soil layers,such as-1℃ and-2℃ permafrost soil elastic modulus;cohesion;and internal friction angle under 9%,12%,and 15%water content conditions,were used to establish a typical railway embankment.The plastic deformation law of the railway subgrade in the permafrost region subjected to natural earthquake loads under temperature increase and strength degradation was analyzed.The results show that with increasing temperature,the frozen soil degraded.At the foot and subgrade center,plastic deformation at-1℃ was greater than that at-2℃.The plastic deformation of the left and right slopes followed a symmetric distribution law.The soil temperature of the typical railway subgrade was raised from-2℃ to-1℃.In 9%moisture content,the plastic slope of the soil layer was 3.5 times larger in the left slope and 4.9 times in the right slope.Moreover,the 12%water content test showed that the plastic strain in the soil layer was 1.6 times larger in the left slope and 2.5 times in the right slope.The tested soil layer with 12% moisture content under permafrost degradation showed good stability,and under the same stress conditions,the plastic deformation increased minimally.