Effect of freeze-thaw cycles and water content on the mechanical properties of moraine soil

Abstract

Objective Moraine soil in seasonal permafrost areas is significantly affected by freeze-thaw cycles, which greatly affects the stability and safety of projects. Methods To investigate the effect of freeze-thaw cycles and water content on the static mechanical properties of the soil, the influence of freeze-thaw cycles and water content on the mechanical parameters of Hailuogou moraine soil was studied via an unconsolidated-undrained triaxial test. Results The results show that the stress-strain curves of the moraine soil before and after freeze-thaw cycling exhibit weak strain softening. With an increase in the number of freeze-thaw cycles, the elastic modulus and shear strength of the moraine soil first rapidly decrease and subsequently tend to stabilize. The higher the water content is, the greater the decay degree of the mechanical parameters. As the number of freeze-thaw cycles increases, the cohesion decreases exponentially, while the friction angle does not change significantly. The exponential function is thus adopted for multiple nonlinear fittings of the shear strength and elastic modulus. The relationship between mechanical parameters and confining conditions pressure, water content, and freeze-thaw cycles are obtained and show good correlation, which can be used to deduce the mechanical parameters of moraine soil after freeze-thaw cycles. The freeze-thaw cycles weaken the mechanical properties of moraine soil, and the higher the water content is, the greater the degree of attenuation. Conclusion The obtained results and analyses can provide scientific support for engineering design and construction in alpine regions.

Keywords

• moraine soil
• freeze-thaw cycles
• water content
• mechanical property
• attenuation pattern