Analysis of the mechanical effects and influencing factors of cut-fill interface within loess subgrade

Abstract

Cut-fill interfaces within the loess subgrade tend to form potential failure surfaces, controlling the mechanical properties of cut-fill engineering. Focusing on the cut-fill interface, extensive laboratory tests in this research show the performance of interfacial mechanical properties under various test conditions, revealing interface effects and exploring the impact of different factors on these effects. The results indicate that the interface strengthens the friction angle of soil but weakens cohesion, especially impacting the cohesion, thereby reducing the shear strength of soil. The increase in dry density diminishes the enhancement effect on friction angle caused by the interface while amplifying the degradation effect on cohesion. Elevated water content has a weak influence on the enhancement effect of friction angle but diminishes the degradation effect of cohesion. Load doesn't change the impact of dry density on the interface effect but amplifies the impact of water content. The impact of various factors on interfacial shear strength manifests as follows: load > average dry density > water content. The interaction among these factors demonstrates average dry density + load > water content + load > average dry density + water content. The study indicates that the construction of loess subgrades based on the standard of maximum dry density and optimum water content may not align with the conditions required for achieving optimal stability at the cut-fill interface. These research findings reveal the crucial role of various factors in comprehensive impact of interfacial effect, offering essential support for ensuring the stability of cut-fill interfaces.