冻融循环对盐渍土黏聚力影响的试验研究

通过室内试验,测试了冻融循环对不同含盐量和不同含盐类别盐渍土黏聚力的影响规律。从结晶体位置变化、微观结构、盐类性质及未冻结水含量三个方面分析了冻融循环对盐渍土黏聚力的作用机理。研究结果表明,在含水率一定的情况下,无论是向土中加入Na2SO4,或者是CaCl2,经冻融循环后黏聚力都随冻融次数的增加而减小,且第1次和第2次循环为主要减小阶段;加入CaCl2后黏聚力的减小程度比加入等量Na2SO4后小;冻融循环过程中结晶体析出时位置的变化是土体黏聚力和干密度减小的主要原因;经SEM图片分析,大孔隙占总孔隙面积的比例随冻融次数的增加而减小;盐渍土中CaCl2溶液的含量对冻融循环中黏聚力的变化有重要影响。

Testing study on influence of freezing and thawing circulation on saline soil''''s cohesion

In order to find the mechanism of the effect of freezing and thawing circulation on the cohesion of saline soil,saline soil samples have been tested in laboratory.By analyzing the variation of the crystalloid location,the microstructure,the salt property and unfreezing water content,the mechanism between freezing and thawing circulation and cohesion is obtained.The research results show that while moisture content is constant,adding either sodium sulfate(Na2SO4) or calcium chloride(CaCl2) to the soil samples,the cohesion reduces with freezing and thawing time increasing.And the primary phases of cohesion reduction are the first and second circulation.The degree of cohesion reduction by adding CaCl2 is minor than adding Na2SO4.The main reason of the reduction of both cohesion and density is that the variation of the crystalloid location occurs while they separate out during freezing and thawing circulation.From the scanning electron microscope(SEM) graph,it is easy to find out that the proportion of big pores of the samples shrink with freezing and thawing circulation time increasing.The content of CaCl2 solution in saline soil has an important influence on the cohesion variation in freezing and thawing circulation.