重塑粘质黄土冻胀敏感性试验分析

Experimental Analysis of Frost Susceptibility for Remolded Clayey Loess

以沈哈高速铁路沿线具有代表性的粘质黄土为研究对象,在室内冻胀试验条件下,研究了非饱和含水量、冷端温度、冻结速率、补水条件以及冻融循环对土体冻胀特性的影响。试验表明,在封闭系统下,非饱和土体冻胀系数随含水量增大而增大,且最终趋于一个稳定数值;封闭系统下,随着冷端温度的降低,含水量较大土样的冻胀系数逐渐减小,含水量较小土样的冻胀系数逐渐增大;开放系统下,土样冻胀系数随冻结速率的减小逐渐增大,且增幅越来越大;外界补水条件下,土体冻胀量增加显著,但随含水量的增大,其影响逐渐减弱;干密度较小土样的冻胀总变形随冻融循环次数的增加呈指数递减的趋势,干密度较大土样则呈指数增加的趋势。

A typical clayey loess obtained along the Shenyang-Ha＇ erbin Express Railway was taken as a case study. The effect of non-saturated water content, temperature, freezing rate, supplying water condition and freezing-thawing circulation on the frost susceptibility of soil were investigated with freezing and thawing experiments. It was shown that in the closed system, the frost heaving ratio of unsaturated soil increased with water content increasing and eventually reached a stable value. And for the soil samples with low water content, the frozen heave rate increased with the decrease of temperature. While for the samples with relatively higher water content, the frozen-heave rate decreased with the increase of temperature. As regards the open system, the frost heaving ratio increased with a growing gradient as the freezing rate decreased. Water-feeding made the frost heave amount increase significantly, while less with the increase of water content. The frost heave deformation showed exponential decline trend with the increase the frequency of freezing and thawing for soil with low dry density, while exponential increase for the soil with high dry density.