Variation characteristics and influencing factors of loess shear strength in seasonal frozen soil region

Abstract:

Loess is a kind of special soil, whose mechanical characteristics are easily affected by hydro-thermal effect. In this study, a typical type of loess (Lanzhou loess) in western China was selected as the research object to investigate the effects of temperature, degree of compaction, and water content on the shear strength of seasonal frozen loess through low temperature triaxial test. Results showed that the cohesion and internal friction angle of the frozen Lanzhou loess increased with the decrease in temperature. The cohesion was greatly affected by temperature, while the internal friction angle was relatively less affected by temperature. In addition, the cohesion and internal friction angle of the frozen Lanzhou loess increased with the increase in the degree of soil compaction. In terms of water content, ice crystal and unfrozen water in the soil changed the strength of soil skeleton and the bonding force between soil particles and ice. Taking the optimal water content of the soil as the boundary point, the shear strength of the frozen Lanzhou loess on both sides of the boundary point showed opposite changing trends. It can be concluded that temperature, compaction degree, and water content have great influence on the shear strength of the frozen loess in Lanzhou, which should be fully considered in the engineering construction of the seasonal frozen soil region covered by loess.