Abstract

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Title:: Effect of Irrigation Leaching on Physical and Mechanical Properties of Undisturbed Loess

Author(s):: ZHENG Ya-meng; DAI Fu-chu; College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China

Keywords:: geotechnical engineering; undisturbed loess; triaxial test; irrigation leaching; physical and mechanical properties; static liquefaction; loess landslide; Gansu

Abstract:: Agricultural irrigation in Heifangtai area of Gansu has induced a large number of landslides, which threaten the safety of the local residents. In order to investigate the mechanism of the irrigation-induced loess landslide, the variations of material composition and physical properties of undisturbed loess caused by long-term irrigation were analyzed; laboratory triaxial tests were performed to further study the effects of irrigation leaching on static liquefaction characteristics inherent in undisturbed loess. The results show that long-term irrigation leaching results in the decrease of contents of soluble salt in undisturbed loess, weakening in the cementation, the dispersion of coarse particles and the increase of clay particle and plasticity index; meanwhile, the wetting collapse in the process of irrigation causes the increase of dry density and the decrease of void ratio; all saturated loess before and after leaching are characterized by static liquefaction in isotropically consolidated undrained compression testing; compared with loess without leaching, the loess leached is characterized by smaller brittleness with the increase of peak strain, the decrease of excess pore water pressure and the upward of steady state line.