Strength characteristics of loess in the landslide area of Ili Naba Highway

ZHANG Yan; ZHU Linxuan; XIE Hongli; TIAN Yeqing; REN Yubo; SUI Zhongtong

doi:10.3969/j.issn.1672-0032.2025.06.007

Abstract：To explore the strength characteristics of the loess in Ili,remolded loess from the landslide area along the Naba Highway in Ili,Xinjiang is selected as the test object.Through triaxial shear tests,ring shear tests,and radial fracturing tests,the impact of different moisture capacity on the shear strength,residual strength,and tensile strength of the soil is analyzed.Combined with scanning electron microscope tests,the microscopic morphology of the soil samples after ring shear failure is observed.The research results indicate that:1)Under the same moisture capacity,the shear strength of the soil samples significantly increases with the increase of confining pressure;under the same confining pressure,the shear strength of the soil samples significantly decreases with the increase of moisture capacity;when the confining pressure is not greater than 200 kPa,the stress-strain curve of the soil samples shows that after reaching peak strength,the shear strength decreases with the increase of axial strain,eventually approaching the residual strength;when the confining pressure is greater than 200 kPa,the stress-strain curve of the soil samples has no obvious peak point,and the shear strength gradually increases with the increase of axial strain.After the moisture capacity reaches 20％,the stress-strain curve changes from strain hardening to strain softening;when the moisture capacity increases from 14％to 17％,the reduction of the shear strength of the soil samples is the greatest.2)When the normal stress changes from 100 kPa to 400 kPa,both peak strength and residual strength increase with the increase of normal stress,and the curves are similar under the same moisture capacity conditions;under different moisture capacity,the shear strength increases rapidly to the peak strength and then slowly decreases with the increase of shear displacement;when the moisture capacity is not greater than 17％,the curves exhibit strain softening characteristics,while the moisture capacity is not less than 20％,the curves only include two stages:strain hardening and residual strength,without strain softening phenomena.3)The residual strength of the soil samples is linearly positively correlated with normal stress,and the tensile strength decreases with the increase of moisture capacity.The tensile strength of undisturbed soil samples and remolded sample tends to be consistent when the moisture capacity is not less than 17％,and slowly decreases;the tensile strength of the soil samples is close to the residual cohesion,indicating that cohesion is the main source of tensile strength.