不同冻结条件下辽西风积砂土动力参数试验研究

为研究不同冻结条件对辽西风积砂土动力参数的影响， 以京沈客运专线阜新段路基为研究背景， 利用GDS冻土动态三轴测试系统对不同温度、 水分、 冻融次数下风积砂土的动弹性模量及阻尼比进行了测试， 获得了土体动弹性模量及阻尼比的变化规律， 提出了风积砂土动力参数的修正系数。结果表明： 随着环境温度的降低， 土体动弹性模量逐渐增大， 阻尼比逐渐减小， 温度与动弹性模量之间近似呈线性关系， 与阻尼比呈指数关系； 随着含水率的增加， 土体动弹性模量逐渐增大。存在着一个含水率敏感区间， 在此区间内动弹性模量变化较为明显， 含水率与阻尼比之间关系不明显， 随着含水率的增加阻尼比稍有降低； 随着冻融循环次数的增加动弹性模量逐渐降低， 阻尼比逐渐增大， 前5次冻融循环对土体动力参数的影响较大， 之后影响逐渐减小。在此基础上， 建立了风积砂土动力参数的修正系数， 能够较好的反映不同冻结条件下土体动力参数的变化规律， 为季冻区铁道工程建设提供参考。

Experimental study on dynamic parameters of aeolian sand in western Liaoning Province under different freezing conditions

In order to study the influence of different freezing conditions on the dynamic parameters of aeolian sand in western Liaoning Province， taking the Fuxin Section of Beijing to Shenyang Passenger Line as the research background， the effects of temperature， water content， freeze-thaw cycles on dynamic elastic modulus and damping ratio of frozen soil were tested by using GDS dynamic triaxial testing system. The variations of dynamic modulus and damping ratio of soil were obtained， and the correction coefficient of aerodynamic parameters of aeolian sand was proposed. The changes of dynamic modulus and damping ratio of soil were obtained， and the correction coefficient of dynamic characteristic parameters of aeolian sand was given from the test. The results show that with decrease of ambient temperature， the dynamic modulus of soil increases gradually， and the damping ratio decreases gradually. The temperature is approximately linear changing with elastic modulus， and is exponentially related to damping ratio. With the increase of water content， the dynamic modulus of soil increases gradually； there is a sensitive interval of water content， in which the dynamic modulus of elasticity changes obviously. The relationship between water content and damping ratio is not very obvious， and the damping ratio decreases slightly with the increase of water content. With increase of freeze-thaw cycles， dynamic elastic modulus decreases gradually， and the damping ratio increases gradually. During the first five freeze-thaw cycles there is great influence on the dynamic parameters of soil， and then the influence decreases gradually. The correction coefficient of the dynamic parameters of the aeolian sand is worked out， which reflects the variation of the dynamic parameters of the soil under different freezing conditions， and would be useful for railway construction in seasonal frozen areas.