[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 con-tent 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 cyc-ling 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 con-tent 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 func-tion is thus adopted for multiple nonlinear fittings of the shear strength and elastic modulus.The relationship be-tween 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.
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