Influencing Factors and Significant Analysis of Mechanical Properties of Silty Clay Subgrade in Seasonal Frozen Area

Abstract

To explore the influence of different factors on the mechanical properties of highway subgrade soil, taking the soil specimen of the highway roadbed in Zhangjiakou as a research object, the factors of freezing and thawing times, water content, compaction degree, and freezing negative temperature are investigated. Using an orthogonal test design, freeze–thaw, temperature monitoring, and static triaxial tests are conducted. Significance analysis of the orthogonal test results is applied to determine the effect of the interaction between the factors, both individually and in combination, on the static strength, internal friction angle, and cohesion of the soil. Test results show that (1) after freeze–thaw cycles, the factors that significant influence the soil strength, cohesion, and internal friction angle are water content, compaction degree, freeze–thaw cycles, and freezing negative temperature; (2) these factors affect the freezing and thawing rate of soil samples, which affects the change of soil mechanical properties; (3) for increasing freezing and thawing times, the soil strength decreases continuously, and the intensity decay trend is slow after the fifth freeze–thaw cycle.