无黏性土压缩模型及其验证

Compression model for cohesionless soils and its verification

土体本构模型的建立往往需要以等向压缩模型为基础。通过对无黏性土等向压缩特性的分析,发现无黏性土等向压缩状态下压缩指数的大小与当前孔隙比和球应力密切相关,进而提出了以当前孔隙比和球应力为变量的可分离函数表示的压缩指数表达式。在此基础上得到一个可以描述无黏性土压缩特性的三参数压缩模型。与试验数据的对比表明,该模型能够较好地拟合不同初始孔隙比下无黏性土等向压缩试验的孔隙比-应力关系。与以极限压缩曲线为参考线建立的压缩模型相比,在拟合低应力区无黏性土的孔隙比-应力关系时,提出的新模型更具有实用性。新模型也可为无黏性土建立本构模型提供基础。

The establishment of soil constitutive model is often grounded on the isotropic compression model.Based on the analysis of the isotropic compression characteristics of the cohesionless soils,it is found that the value of the compression index is closely related to the current void ratio and spherical stress.On this basis,an expression of the compression index formulated as a separable function of the current void ratio and spherical stress is established.Then,a three-parameter compression model that describes the compression characteristics of the cohesionless soils is obtained.The comparisons with test data of four types of sands show that the model can properly fit the relationships between void ratios and stress of cohesionless soils with different initial void ratios.Compared with the compression models established by taking the limit compression curve as the refence line,the proposed model is more useful in fitting the relationships between void ratios and stresses of cohesionless soils in low-stress regions.The model also provides a foundation for establishing constitutive models of cohesionless soil.