用有效应力解释非饱和土的弹塑性行为

Interpretation of elasto-plastic behaviors of unsaturated soils based on effective stress

在巴塞罗那基本模型BBM模型的框架下,应用有效应力和应力双变量分别解释非饱和土弹塑性行为的不同特点。对文献试验数据的分析表明:在应力双变量构成的应力空间中,存在两个初始LC屈服面,加载强化过程中也具有两个LC后继屈服面;相反,有效应力空间中,非饱和土具有唯一的初始LC屈服面,加载强化过程中LC屈服面也保持唯一。非饱和土在两个应力空间中的不同表现与非饱和土的水分滞回性质相关。与采用应力双变量的弹塑性模型不同,采用了有效应力的弹塑性模型,可直接反映水分滞回的影响。

Under the framework of BBM （Barcelona Basic Model ）, the different elastoplastic characteristics of unsaturated soils are explored by using the effective stresses and the two independent stress variables. Analysis of published test data shows that in the space of two independent stress variables, there are two initial LC yield loci, and two subsequent LC yield loci during hardening due to loading. On the contrary, in the effective stress space, there is a unique initial LC yield locus and thereby a unique subsequent hardening LC yield locus. The difference of LC yield loci in different stress spaces results from the hydraulic hysteresis of soil-water characteristics. Contrary to the elastoplatic model using two dependent variables, elastoplatic model using effective stress may directly reflect the influence of hydraulic hysteresis.