固结蠕变下软土微观结构参数的定量分析

为了探究土的微观结构特性和更加准确的描述土的变形过程,从微观上分析珠三角地区软土的固结蠕变,对软土的微观结构特征、孔隙个数和直径、孔隙和颗粒丰度、孔隙定向频率等方面进行了定量分析,对代表性广州番禺地区的土样试验结果表明:原状土样的微观结构主要是以蜂窝状和基质状结构为主,土体颗粒接触方式主要为点-点接触和点-面接触;当施加轴向固结荷载时土体的结构发生变化,轴向荷载较大时,土体的微观结构以紧密的骨架状和紊流状结构为主,土体颗粒的接触方式以面-面接触为主。软土在蠕变过程中,土体颗粒和孔隙大小的变化都遵循大孔隙优先改变原则,颗粒和孔隙的边界变得圆滑且形状趋向于扁圆形。蠕变后,颗粒和孔隙的个数有明显增加,直径都有明显减少,孔隙丰度值和复杂度有所降低。原土的分形维数高于土体蠕变变形后的分形维数。当固结应力增大时,土中孔隙的分形维数不断减小,大孔隙不断减少,大颗粒破损,小颗粒被挤入大孔隙中,颗粒和孔隙朝着均匀化方向发展。

Quantitative Analysis of Microstructure Parameters of Soft Soil Under Consolidation Creep

In order to explore the microstructure of soil and describe the deformation process of soil more accurately. This article from the microscopic analysis of soft soil consolidation creep of pearl river delta, on the microstructure characteristics of soft soil, number and pore diameter, pore and grain abundance, pore directional frequency and so on has carried on the quantitative analysis of the experimental results show that: Undisturbed soil samples in guangzhou region is the main honeycomb and matrix structure on microstructure, soil particle contact way for side - the side and side - surface contact;When the axial consolidation load is applied, the structure of soil changes. When the axial consolidation load is large, the microstructure of soil is dominated by tight skeleton and turbulent structure, and the contact mode of soil particles is dominated by surface to surface contact. In the creep process of panyu soft soil, the changes of soil particles and pore sizes follow the principle of macropore preference, and the contours of particles and pores become "smooth" and tend to be oblate.After creep, the number of particles and pores increased, the diameter decreased, and the abundance and complexity decreased. The fractal dimension of the panyu undisturbed soil sample is higher than that of the soil after creep deformation. When the consolidation stress increases, the fractal dimension of the pores in the soil keeps decreasing, and the big pores keep decreasing, the big particles are damaged, and the small particles are squeezed into the big pores, and the particles and pores develop towards homogenization.