延边地区膨胀土冻胀特性及起始冻胀含水率试验研究

Experimental study on frost heaving characteristics and critical frost heaving water content of expansive soil in Yanbian area

季冻区膨胀土可能产生多种工程病害隐患,以吉林省延边地区膨胀土为研究对象,在封闭系统条件下对膨胀土进行不同因素(含水率、冻结温度及压实度)的冻胀试验,研究膨胀土的冻胀特性及起始冻胀含水率的影响因素,并对试验结果进行分析。试验表明:不同含水率试样冻胀量随时间呈现“冻缩型”“先冻胀后冻缩型”“先冻缩后冻胀型”这3种冻结类型。低含水率试样冻胀量为负值,高含水率试样冻胀量为正值,冻结温度越低冻胀量越大、冻缩量越小;试样冻胀和冻缩变形量随压实度增大逐渐减小。起始冻胀含水率随冻结温度的降低和压实度的增大而呈线性减小,并提出了不同冻结温度和压实度条件下膨胀土起始冻胀含水率的经验公式。

The expansive soil in the seasonally frozen area has the potential to produce various engineering diseases.Taking the expansive soil in Yanbian area of Jilin Province as the research object,the frost heaving tests of different factors(moisture content,freezing temperature and compaction degree)were carried out on the expansive soil under the closed system conditions,and the frost heaving characteristics of the expansive soil and the influencing factors of the critical frost heaving water content were studied,and the test results were analyzed.The results show that the frost heave of the samples with different water content presents three types of freezing with time‘freeze shrinkage type’,‘first frost heave and then freeze shrinkage type’and‘first freeze shrinkage and then frost heave type’.The frost heave of low water content sample is negative,and that of high water content sample is positive.The amount of frost heaving increases with the decrease of freezing temperature,while the amount of frost shrinkage decreases.The frozen deformation of the sample decreases with the increase of compactness.The critical frost heaving water content decreases linearly with the decrease of temperature and the increase of compaction degree,and an empirical formula for the initial frost heaving water content of expansive soil under different freezing temperatures and different compaction degrees is proposed.