水泥加固砂性土微观特征试验研究

通过电动体视显微镜微观试验手段,研究了不同水泥掺量下水泥加固砂性土加载前后微观特征,并分析了水泥加固砂性土孔隙的形状系数、定向角和孔径大小等参数的变化规律,揭示了水泥砂性加固土体强度及承载机制的演化特征。结果表明:(1)水泥砂性加固土在加载前后孔径分布和孔隙形状系数在水泥掺量5%~10%范围内同时存在剪缩和剪胀;但水泥掺量高(＞10%)的加固土加载后整体宏观表现为剪胀;(2)在加载条件下,水泥加固砂性土体的颗粒或团粒会发生定向滑移或转动,并在一定程度上孔隙长轴的方向会发生改变。且孔隙定向角分布形式逐步由均匀向集中转变,孔隙分布呈现显著的定向性。

Microstructure Research on Cement Stabilized Sandy Soils

The microstructure of cemented sandy soils, which is made from different original soil as well as with various cement contents, is investigated by ESEM method. Then, the data of pore such as the diameter, shape index and orientation angle are analyzed via image processing technology, and the evolution law of the strength of cemented sandy soil and bearing mechanism are explored. Comparing the results got from the loaded and unloaded samples, they show: (1) the performance of pore diameter and pore shape shows a contraction and dilation phenomenon at the same time under the cement content (5%~10%), while pore diameter reducing and coefficient of pore shape increasing. However, shear dilation usually happens under the highest cement content (10%). (2) During the loading process under the interaction of internal stress, particles of cemented sandy soils will directionally slide or rotate. In addition, pore axis direction of cemented sandy soils changes as well, and orientational angle changes from uniform into concentration, and pore directional characteristic is obvious.