Abstract
Shear strength and crack characteristics are crucial factors in determining the
engineering properties of expansive soils. In this study, direct shear tests, triaxial shear
tests, and crack development tests were implemented to assess the impacts of cement
content and dry-wet cycles on the mechanical behavior of expansive soil. The fullsurface fracture indices of the triaxial specimens were extracted, and a comprehensive
fracture index was calculated. Subsequently, a Support Vector Machine (SVM) model
was established to analyze the development of cohesion. The findings indicated that
the shear strength and its parameters decrease as the frequency of dry-wet cycles
increases, and they initially rise and then fall with the increase in cement content. The
maximum shear strength occurs at a cement content of 6%-8%. The correlation
between comprehensive fracture index and strength index is better than that of single
fracture index, and the correlation between average crack width is the strongest. The
support vector machine model is established by replacing the average width of cracks
with dry-wet cycle frequency. The model has a small prediction accuracy error, strong
adaptability, and high potential. The findings of this study indicate that crack index
analysis can effectively simulate the cohesion of expansive soils, demonstrating
significant practical potential for engineering construction in expansive soil regions.
This approach provides important theoretical support and technical guidance for
construction practices in areas characterized by expansive soils.
Keywords: Improved Luoyang expansive soil, Shear strength, Dry-wet cycles, Macro-tomesoscopic correlation analysis, Support vector machine.
