Abstract:

To study the relationship between shear stress and shear displacement at the nail-soil interface, as well as the variation of interfacial shear strength and apparent friction coefficient with changes in soil water content and stress state, a pull-out shear test was conducted on the interface between silt and nail under controlled water content in this paper. The results of the soil-nail interface shear test were compared with those of the soil-structure shear test. Additionally, a calculation analysis of the shear stress at the nail-soil interface was conducted. The results show that the shear stress at the nail-soil interface increases significantly with the increase in overburden pressure, and the pull-out displacement corresponding to the peak shear stress also increases gradually. Meanwhile, a softening phenomenon occurs after the shear stress reaches its peak. The shear stress at the soil interface is negatively correlated with the soil’s water content. The shear stress in the low water content silt test is almost double that of the saturated silt test, and the pull-out displacement corresponding to the peak shear stress also increases by about twofold. The peak and residual shear stresses increase approximately linearly with increasing overburden pressure, and decrease significantly with increasing soil water content (w). The difference between them decreases with increasing w, and increases with increasing overburden pressure. The research results can provide a reference for studying the pull-out bearing capacity of nails.

Key words: silt, water content, soil-nail, interface pull-out, shear characteristics