Hydraulic-mechanical properties of loess and its behavior when subjected to infiltration-induced wetting

Abstract

Water retention, unsaturated permeability, and deformation-failure characteristics induced by infiltration were studied by analyzing stress-dependent soil–water characteristics and the wetting stress path of unsaturated intact clayey loess in Baoji, China. Test results in Baoji and Heifangtai were compared. The results show the following: (1) The soil–water characteristic shape is related to stress, and suction decreases with water content; (2) the van Genuchten model is applicable to the clayey loess in Baoji, (3) the unsaturated permeability coefficient is related to stress, which increases with axial net stress; (4) under certain confining stress, hydraulic properties of loess vary considerably by region and, compared with loess in Heifangtai, the water retention capacity of clayey loess in Baoji is greater; (5) brittle deformation is dominant in Baoji but plastic deformation is dominant in Heifangtai; and (6) deformation behavior and the strength of loess is related to the confining stress, and the combined action of that stress and suction cause breakage of loess cementation bonds. The decrease of matric suction is not necessary for loess deformation, but the breakage of cementation bonds is the essence of the decreasing strength and final deformation failure of loess.