The change of mechanical strength and microscopic mechanism of loess in Ili area under the superposed effect of snow melting and rainfall

Abstract

The period with the highest water content of the slope in Ili area is from mid-March to mid-May every year. From April to June, landslide disasters occur frequently, and it is also the period of ice and snow melt water and rainfall. The formation mechanism of a loess landslide is different because of the difference in natural geography and geological environment background conditions. According to the characteristics of rainfall infiltration in the slope of Ili Valley, it is urgent to carry out research on the formation mechanism of ice and snow melt infiltration gain rainfall loess landslide. This study explores the macro and micro characteristics and their correlation of loess in the Ili area under varying water content conditions through laboratory triaxial compression tests, Scanning Electron Microscopy (SEM) and Nuclear Magnetic Resonance (NMR). The results reveal a quadratic parabolic relationship between cohesive force, internal friction angle and moisture content, with both cohesive force and internal friction angle increasing initially with moisture content before decreasing. Water content primarily affects the cohesive force of loess in the Ili area, with minimal impact on the internal friction angle. Microstructural tests identify an optimal moisture content for Ili loess, where the particles are the largest, most equiaxed, with simple contour lines and well-arranged structures. Grey relational analysis demonstrates the closest relationships between pore size fractal dimension and loess cohesive force, as well as between particle size fractal dimension and internal friction angle. The quantitative analysis of the macro- and micro-structure of Ili loess provides valuable insights for landslide prevention and management in the Ili River Valley.