MICRO EXPERIMENTAL RESEARCH ON INFLUENCE FACTORS OF LOESS COLLAPSIBILITY

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 of microstructure 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.