冻融作用对伊犁黄土孔隙结构及剪切特性的影响OA

To clarify the damage mechanisms by which freeze-thaw cycles trigger snowmelt-induced loess land-slides,this study examines the Jialangpute loess landslide in the Ili region of Xinjiang.CT scanning and direct shear tests were performed on soil specimens with water contents ranging from 5%to 30%after 0-10 freeze-thaw cycles,enabling a quantitative analysis of micropore evolution and the corresponding degradation of macroscopic shear strength.The results reveal three distinct stages of microstructural damage under freeze-thaw action:an in-tensive damage stage,a crack coalescence stage,and a structural reconfiguration stage.As the number of freeze-thaw cycles increases,porosity,total pore count,and fractal dimension first rise and then decline,whereas pore orientation evolves from dispersed to concentrated and ultimately to uniform.The degradation of shear strength is manifested primarily through cohesion,which undergoes rapid decline,gradual recovery,and eventual stabiliza-tion.Correlation analysis confirms a significant negative relationship between cohesion and both total porosity and macroporosity,indicating that the increase in porosity and the enlargement of individual pores under freeze-thaw action directly weaken interparticle cementation.When the water content exceeds the optimum range of 10%-15%and approaches saturation,the coalescence of small pores into larger ones promotes the infiltration of rainwater and snowmelt,producing a sharp drop in cohesion.This process constitutes the micromechanical mech-anism underlying loess landslides in the Ili region.The findings provide a theoretical basis for slope-stability as-sessment and engineering mitigation of loess landslide hazards in the seasonally frozen regions of Central Asia.