中文摘要：

为了探讨无荷条件下膨胀率与初始含水率和膨胀时间的关系,采用WZ-2型膨胀仪,通过室内无荷膨胀率试验对4组不同初始含水率的延吉盆地原状膨胀土进行了研究。试验结果表明：试样初始含水率越低,无荷膨胀率越大。各不同初始含水率下膨胀时程曲线都有着明显的规律性,可将曲线分为三个阶段：等速膨胀阶段、减速膨胀阶段和稳定阶段。试样的膨胀变形主要发生在试验的前30 min内,用Knothe时间函数模型对各组试验前30 min内的数据进行拟合,构建了膨胀时程方程,并详细分析了方程中的未知参数的物理意义及其影响因素。其中,参数a为试样的最终无荷膨胀率,其值的大小与试样初始含水率密切相关。参数b为初始膨胀速率参数,由于受多个因素的影响,其值的确定需要进一步的研究。最后,通过误差比较可知,基于Knothe时间函数模型构建的膨胀时程方程的拟合效果要优于多元回归分析。以上结论为进一步研究延吉膨胀土的膨胀机制奠定了理论基础。

英文摘要：

In order to study the swelling characteristics of the original expansive soils,the indoor free expansion ratio tests were carried out for the Yanji Basin expansive soils. The expansion ratio measurements using a WZ-2 dilatometer were made for 4 groups of expansive soil samples under different initial moisture.The results show that the lower the initial moisture is,the larger the expansion ratio is. The deformation of the expansive soils mainly occurs in 30 min after the tests started. The swelling curves have obvious rules,and can be broadly divided into three stages： constant-rate swelling stage,drop-rate stage and steady stage. Based on the test data,the relationships with high coefficients are dropped between the expansion ratio and time by adopting Knothe time function,and the physical meaning of the unknown parameters is analyzed in detail. The parameter a equals to the final value of expansion ratio,and the parameter b is related to the initial expansion rate. There is a strong negative correlation between the value of a and the initial moisture. The parameter b is affected by various factors,and its determination still needs further research. It is also found that the match results with the Knothe time function to predict the expansion ratio by error analyses and comparisons are more reasonable than those of the multiple regression analysis. The conclusions will provide the theoretical foundation for the further study of the swelling mechanism in future.