基于单线法试验的黄土增湿变形非线性模型研究

Study on nonlinear constitutive model for loess moistening deformation based on single-line experiment method

黄土增湿变形一般由地面水入渗或地下水位抬升引起,是岩土工程中需要解决的一个技术难题。虽然在该领域有一些研究,提出了描述该变形的本构模型,但是与实际地基中力和水的作用路径有较大差异。本文引入"增湿水平"这一概念来描述黄土的湿度状态,通过开展分级浸水试验,着重研究先施加应力后浸水增湿路径下黄土的湿度状态与增湿变形的相关关系,建立了增湿变形非线性本构模型;用增湿变形系数和湿陷系数的比值与增湿水平关系曲线反映黄土增湿变形的敏感性,分析了竖向应力、土质对黄土增湿变形敏感性的影响;采用不同应力比的增湿水平与侧向变形曲线,分析了增湿过程中的侧向挤出变形规律。

Loess moistening deformation,generally caused by surface water infiltration or the rise of under-ground water level, is a critical technical problem to be solved in geotechnical engineering. The existingconstitutive model can be used to describe loess moistening deformation. However, it is still greatly differ-ent from the acting path of stress and water in actual foundation. This paper introduces the concept of hu-midification level to describe the moisture condition of soil. With stepped wetting tests on original loess,the correlations between soil moistening deformation and moisture condition during wetting process under theaction of stress were analyzed, and the nonlinear constitutive model for loess moistening deformation hasbeen established. The relationship curves of humidification level and the ratio between humidification defor-mation coefficient and collapsibility coefficient are used to reflect the sensitivity of loess moistening deforma-tion. Besides,it also deals with the influence of vertical stress and properties of loess on the sensitivity ofloess moistening deformation. The lateral deformation characteristics in humidifying process are analyzed byadopting humidification levels and lateral deformation relationship curves with different stress ratios.