膨胀土一维湿化变形时效特性的半经验法研究

Semi-empirical study on one-dimensional wetting deformation respect to time for expansive soil

为探索膨胀土渗透作用下湿化变形时间效应的预测方法,设计一系列具有一定初始含水率和干密度的标准环刀试样的一维吸水膨胀试验,对试样的膨胀变形随时间变化规律进行分析。采用室内试验、数据统计分析与有限单元法相结合,理论计算出膨胀土的吸水膨胀率随时间的变化关系。室内无荷载膨胀试验获取了隆起量随时间的变化规律;将滤纸法获得的膨胀土的土-水特征曲线,应用于有限元分析软件中,获得了试样渗透吸水过程中体积含水率随时间的变化规律;最后将试验获得的膨胀率-过程含水率的理论与体积含水率随时间变化的数值模拟结果相结合,获得了土体隆起变形随时间变化的理论预测曲线。研究结果表明:半经验公式获得的隆起量-时间关系与试验数据基本一致;结合已有研究验证该半经验方法的准确度,结果得到的膨胀量随时间变化的计算结果与实测相同,说明本文提出的半经验计算方法具有良好的应用前景,可用于膨胀土的一维隆起预测。

The estimation method of the wetting deformation of infiltration respect to time for expansive soil was investigated.A series of standard cutting ring-knife specimens were designed with certain initial moisture content and dry density.Through one-dimensional water absorption and expansion tests,the empirical function between the maximum expansion rate of soil mass and the initial moisture content and dry density was obtained,and so was the saturated water content.Based on soil-water characteristic curve(SWCC),the change of volumetric moisture content in soil infiltration process with time was simulatedby using the finite element analysis(FEM).Combined the theoretical formula with the numerical simulation results of the change of volume moisture content respect to time,the change of soil heave respect to time was obtained.Compared with the measured and numerical data,the estimated results from empirical formula with FEM agreed well.The proposed method was promising and could be used in practice for estimation of the 1-D heave with respect to time 。