软黏土修正的Mesri蠕变模型及其工程应用

Modified Mesri creep model of soft clays and its engineering application

以天津滨海软黏土为研究对象,采用分级加载方式进行室内三轴固结不排水蠕变试验。分析试验数据,以Mesri蠕变模型为基础,建立了一种修正的Mesri蠕变模型,该模型将土体变形第一阶段的最终应变视为初始应变,采用应力-应变关系和应变-时间关系均为双曲线函数的组合形式描述变形的第二阶段。通过编制子程序将修正的Mesri蠕变模型嵌入ABAQUS软件,并利用三轴蠕变试验结果对新模型的合理性和子程序的正确性进行验证。最后,将该模型应用于天津滨海地区长期沉降的数值仿真。结果表明,该模型较Mesri蠕变模型能够更好地拟合试验数据,对蠕变特性的数值仿真,能较好地反映和预测天津滨海软黏土蠕变特性,为工程长期变形计算提供依据。

Consolidated undrained triaxial creep tests with a stepwise loading method were carried out on soft clays collected from the coastal area of Tianjin,and by analysing the test data a modified Mesri model was developed.This model takes the final strain in the first stage of creep deformation as an initial strain and describes the deformation in the second stage using the combination of a stress-strain hyperbolic function and strain-time hyperbolic function.It was imbedded into finite element code ABAQUS as a subroutine for soil creep deformation and its calculations were verified by the test data.For further verification,it was applied to simulations of long-term settlement of a soft clay layer in the coastal area of Tianjin.The results show that this modified Mesri creep model fits the test data better than the Mesri model and its calculations can predict the long-term creep deformation characteristics of soft clay layers for engineering projects with a satisfactory accuracy.