ANALYSIS FOR EFFECTS OF LOESS PORE STRUCTURE EVOLUTION ON SOIL-WATER CHARACTERISTICS

As one of the key hydraulic parameters of loess,soil-water characteristic curve(SWCC) is affected by soil pore structure characteristics. However,it lacks the studies about the effects of loess pore structure evolution on its soil-water characteristics. In this paper,L₁,L₂,and L₆ specimens were taken from the loess platform at the southern bank of the Jinghe River in Jingyang County,Shaanxi Province. The evolution characteristics of loess pore structure during deposition were qualitatively analyzed through the scanning electron microscopy,and were quantitatively analyzed using the pore size distribution(PSD)curves. Meanwhile,the SWCCs of each layer of loess were measured by filter paper method,and the variation regularities along the loess profile were analyzed by comparisons of each other. The pore sizes were transformed into the potential suctions through Young-Laplace equation,and then the PSD and SWCC curves were plotted together with the same suction coordinate,finally the dependency of PSD and SWCC curves were analyzed. In details,the dominant pore sizes and their distribution densities decrease with soil depth increase. As a result,saturation sections and air entry values of SWCCs increased,and the transition sections turned to be gentler,which implied that the increasing of water retention capacities. In addition,comparing the PSD and SWCC of remolded soil specimen with that of intact ones,it could be found that the difference increased with soil depths,although both of them had the same water contents and dry densities.