影响黄土湿陷性因素的微观试验研究

MICRO EXPERIMENTAL RESEARCH ON INFLUENCE FACTORS OF LOESS COLLAPSIBILITY

借助扫描电子显微镜和光学数码显微镜,分析了不同含水率黄土试样表面微区结构变化与黄土湿陷性的关系和不同埋深土样在水与外力共同作用下湿陷前后微观结构的变化特征。利用图像处理软件对所获取的微结构图像进行研究,分析了黄土湿陷前后土样中大、中、小孔隙和微孔隙数量的变化。结果表明:湿陷后比湿陷前土样微孔隙增多31.18%,小孔隙增多54.07%,中孔隙减少30.49%,大孔隙减少90.14%。这说明随着压力的不断增大,黄土中的孔隙被逐渐压缩,大孔隙和中孔隙的数量逐渐减少,小孔隙和微孔隙的数量逐渐增加,为黄土的湿陷变形提供了充分的空间。讨论了土样中4类孔隙对黄土湿陷的贡献量,从微观角度综合分析了黄土湿陷的成因机理。

This paper uses scanning electron microscope and optical digital microscope to analyzes the relationship between the structure changes of surface micro-area on loess sample and its collapsibility,the soil samples microstructures at different depths influenced by both water and load before and after loess collapse. The image ofmicrostructure is studied by image processing software. The number variation of large pores,medium pores,small pores and micro-pores before and after the loess collapses are analyzed. The results show that after collapse of the loess,the micro pores increase by 31. 18%,small pores increase by 54. 07%,medium pores decrease by 30. 49%,large pores decrease by 90. 14%. This shows that with increasing of pressure,the pores of loess are gradually compressed. The numbers of medium pores and large pores gradually decrease while the numbers of small pores and micro-pores gradually increase,which provide sufficient space for collapsible deformation of loess. The contribution of the four types of porosity to loess collapsibility is discussed to comprehensively analyze the formation mechanism of loess collapsibility form the micro perspective.