统一模型下粘性土和砂性土液化特性数值研究

考虑到土体介质材料经历弹性卸载后即进入超固结状态,而其反过来又能影响土体的力学与抗液化特性,通过考虑超固结因素的影响,在统一下负荷面剑桥模型下对砂性土与粘性土的力学与抗液化特性进行了数值试验对比研究。结果表明,与粘性土相比,砂性土在加载过程中表现出更高的非线性特征与可压缩性,且在非排水加载下更容易引发屈服和液化。通过考虑土体超固结因素的影响以及不同土体条件下超固结比演化规律的差异,下负荷面剑桥模型在统一理论框架下很好的模拟出了砂性土与粘性土间力学与抗液化能力的差异。同时考虑到土体超固结状态与密实度间的关系,模型也从超固结状态的角度很好的解释了土体抗液化能力与相对密度的关系,且与液化试验实测结果取得了较高的一致性。

Numerical Liquefaction Study of Clayey and Sandy Soils in a Unified Constitutive Model

Considering soil turns into overconsolidated state once experiences stress unloading under cyclic loading, and the state of overconsolidation could affects the mechanical properties and liquefaction characteristics in turn, in this paper, with taking the influence of overconsolidation factor into consideration, comparative numerical studies of mechanical properties and liquefaction characteristics between clayey and sandy soils are carried out in the unified subloading surface Cam-clay model. The research results show that compared with clayey soil, sandy soil has higher compressibility, stronger nonlinear characteristics, and more tends to liquefy under undrained cyclic loading test. Through precisely simulates the effect of overconsolidation, as well as the evolution of OCR, the different mechanical properties and liquefaction resistance between clayey and sandy soils are well simulated in the unified theoretical framework. At the same time, considering the relationship between overconsolidation and relative density of soil, the model also well explained the relationship between liquefaction resistance and overconsolidated state of soil, and achieved high consistency with the observed experimental liquefaction test results.