Physicochemical effect on soil in sliding zone of reservoir landslides.

The fate of reservoir landslides is mainly dictated by the mechanical behavior of soil in the sliding zone. This soil may be altered under changing environmental conditions of both physical and chemical nature. In this paper, we present a laboratory study on the changing soil properties under complex physicochemical interactions. The soil specimens are subjected to 1, 2, 3, 5, 7, and 10 wetting-drying cycles. The soil strength is determined by triaxial tests. These tests are performed with three types of pore water, namely, acidic groundwater (AGW), normal groundwater (NGW), and distilled water (DW). The deterioration of soil strength, the change in soil microstructure and mineral composition are observed and correlated. Interesting findings for reservoir landslides are drawn: acidic underground water considerably damages the soil microstructure and deteriorates the shear strength compared to normal underground water, while distilled water causes minimal disaggregation. A three-stage micromechanism associated with four physicochemical interactions is revealed, providing insights into microstructure damage and mineral transformation. • Combined effect of physicochemical interaction on the shear strength of sliding zone soil. • Microstructure evolution of sliding zone soil by five classified pores. • Variations in minerals and cations signify potential chemical interactions between soil and water. • Four types of physicochemical interactions in the evolution process of sliding zone soil. • Three-stage evolutionary mechanism for soil deterioration. [ABSTRACT FROM AUTHOR]