基于扰动状态概念的非饱和原状Q_2黄土本构模型

Constitutive Model of Unsaturated Intact Q_2 Loess based on Disturbed State Concept

Q_2黄土是典型的非饱和土,具有明显的结构性和一定的湿陷性。在扰动状态概念基础上,建立了一个考虑细观结构演化的非饱和原状Q_2黄土本构模型,并通过试验建立了细观试验数据与土体宏观现象的联系,即通过CT-三轴试验过程中的CT数据表征和测定土样的扰动变量,从而得到结构性土体的扰动函数(结构演化规律)。模型中,以陈正汉等提出的非饱和土增量非线性弹性模型和修正Barcelona非饱和土弹塑性本构模型描述相对完整状态和完全调整状态,以CT-三轴试验为依据建立的扰动函数较为客观真实,从而使模型能更好地描述非饱和原状Q_2黄土的力学特性。模型包括土骨架变形与水量变化两个方面,可对加载过程和湿陷过程进行描述。模型参数均可由试验确定,且通过试验资料初步验证了模型的合理性。

Q_2loess is a typical unsaturated soil,with obvious structural features and some collapsible. Based on disturbed state concept, a constitutive model of unsaturated intact Q_2 loess is developed, which considers the evolution of micro-structure. The relationship between microscopic test data and macroscopic phenomena is established by experiment, which means that through CT data representation and determination of soil sample disturbance variables in CT-triaxial test, structural soil disturbed function(structural evolution) is obtained. In this model,the relative intact state and full adjusted state are described by the non-linear elastic model of unsaturated soils proposed by Chen Zheng-han and the modified Barcelona elasto-plastic constitutive model of unsaturated soils, and the disturbed function based on CT-triaxial test is objective and realistic,thus the physical properties of unsaturated intact Q_2 loess could be described more accurately. The model includes the deformation of soil skeleton and the change of water quqntity,which can describe the loading and collapsible processes. The model parameters can be determined experimentally, and the rationality of the model is verified by the experimental data.