Constitutive model for unsaturated sedimentary soils based on SFG model
Received date: 2017-04-25
Online published: 2019-05-05
为使修正后的模型能够更好地反映非饱和沉积土的持水和力学性质, 对SFG(Sheng-Fredlund-Gens)模型进行修正.用平均骨架应力代替净应力作应力状态变量,考虑饱和度对非饱和土变形的影响.通过分析泥浆固结土(沉积土)在等吸力条件下等向压缩和三轴压缩试验数据,得出饱和度和孔隙比的关系, 并把变形考虑到持水曲线模型中.由修正后的体变方程以及持水曲线方程推导出加载湿陷屈服面方程,在修正剑桥模型基础上推导出三轴应力状态下的本构方程,并采用能统一描述剪缩剪胀性的硬化参数. 基于同一模型参数,模型可以统一预测吸力控制下各向等压和三轴剪切路径下非饱和沉积土的持水和力学特性.
张照, 孙德安, 高游 . 基于SFG模型的非饱和沉积土本构模型[J]. 上海大学学报(自然科学版), 2019 , 25(2) : 337 -346 . DOI: 10.12066/j.issn.1007-2861.1930
The Sheng-Fredlund-Gens (SFG) model is modified by considering coupled water-retention and mechanical behavior to reflect the behavior of unsaturated sedimentary soils. The net stress is replaced with the average skeleton stress for stress state variable, and the influence of saturation on deformation is considered in the model. Based on test data of pre-consolidated clay at constant suctions for isotropic compression and triaxial shear, relationship between degree of saturation and void ratio is found, and the effect of deformation on saturation is considered in modeling the soil-water retention curve (SWRC). The loading collapse yield surface equation is derived from the volume change equation and SWRC equation. On the basis of a modified Cam-clay model, constitutive equations in triaxial stress state are derived with a unified hardening parameter that can describe shear contraction and dilatancy consistently. Using the same values of the model parameters, the hydraulic and mechanical behavior of unsaturated pre-consolidated clay can be consistently predicted under control of suction along isotropic compression and triaxial stress paths.
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