软土固结过程中的微结构变化特征

从粘性土体结构系统观点出发 ,建立了土体结构形态概念模型 ,即土体微结构形态由颗粒形态、颗粒排列方式、孔隙性和颗粒接触关系 4种结构要素定性描述 ,这 4种结构要素分别由颗粒大小、颗粒形状、颗粒定向性等 9种结构参数定量刻划。根据土体具有的非线性特征 ,运用分形几何理论提出了粒度分维、颗粒定向分维等 7项定量表征土体微结构状态的分维指标。在此基础上 ,以厦门软土为例开展了软土固结过程中的微结构变化规律研究 ,发现固结过程中软土微结构要素调整变化具有明显的阶段性 ,前期为剧烈调整阶段 ,后期为缓慢变化阶段 ,整体表现为分维指标下降的趋势 ,从而为软土结构力学模型的建立奠定了基础。

THE VARIATION OF MICROSTRUCTURE DURING SOFT SOIL SOLIDIFICATION

The concept model of soil microstructure is built from the soil microstructure system. It is that the soil microstructure can be qualitatively described by particle formation,particle arrangement,pore character and contact relation of particles. These structure factors are marked by 9 kinds of structure parameters such as fractal dimension of particle and fractal dimension of particle direction etc. According to nonlinear features of soil, 7 fractal dimension parameters to identify structure state of soil were suggested based on the fractal theory. On the basis of the above results, we studied the changing characteristics of soft soil microstructure during solidification using in Xiamen soft soil . It is found from the study that the structure adjustment is characterized by distinct stages i.e.the acute adjustment followed by slow variation, and the fractal dimension parameters trend to decrease in the whole solidification course.These results have laid solid foundations for further building of the mechanical model of soft soil.