黄土初始结构性及其湿载作用下演化规律

Initial structure of loess and its evolution under condition of stress and moisture

黄土的结构性是除粒度、密度、湿度之外更为重要的指标。通过总结分析综合结构势理论框架内业已提出的结构性参数及其演化规律,并将结构性参数分为过程结构性参数和初始结构性参数两类,这种分类说明了合理的结构性参数既要反映土的基本物理属性还要反映其在外部扰动作用下的演化过程。针对目前结构性参数及其演化规律存在的问题,采用能够反映初始结构性的构度指标与反映过程结构性的应力比结构性参数,提出了球应力与剪应力对结构性参数综合影响的综合应变,并分析综合应变与结构性参数之间的关系,建立了一个能反映结构性从初始到湿载作用下衰减演化的数学模型。通过理论分析和常规三轴试验研究表明,该数学模型避免了试验围压对初始结构性的影响,并且考虑了湿载过程中体应变与剪应变的共同影响,更加准确地反映黄土的结构损伤演化规律。

Loess structure is more important mechanical properties of loess besides its particle size, density and humidity. Based on the theory of comprehensive structure potential, we made a synthesis of the existing structural parameters and their evolution, and structural parameter can be of two types： initial structural parameter and the process of structural parameter. Structural parameter tends to satisfy both the basic physical property of soil and its evolution under the condition of stress and moisture. Based on existing problem of structural parameters and their evolution, structure index is used to describe initial structure, and stress ratio structure parameter is used to describe the process of structure. The relationship between stress ratio structural parameter and comprehensive strain is studied. Finally, a mathematical model that can reflect the attenuation evolution of soil structure under the condition of initial stress and moisture is established. Theoretical analysis and triaxial test show that the model can avoid the influence of confining pressure under the condition of triaxial tests on initial structure, and it can consider the influence of body strain and shear strain under the process of stress and moisture. The model can more accurately reflect the damage evolution of loess.