Experimental Study on the Shear Characteristics of Different Pile-Soil Interfaces and the Influencing Factors

In seasonally frozen region, landslides and slope failures start during the thawing season due to the enrichment of water for the surface soil layer. Piles and anchored system are common remediation techniques in slope reinforcement projects. A cost-effective and reliable design relies on a comprehensive understanding of the interfacial shear characteristics of the pile-soil interface under different in-situ conditions. Series of laboratory direct shear tests are performed to evaluate the shear characteristics of wood-soil, concrete-soil, and steel-soil interfaces. The effects of soil density, water content and freezing-thawing cycles on the interfacial shear behavior are investigated and a multi-linear regression formula is proposed to predict the interfacial shear strength parameters. Test results show that the cohesion and friction angle at the pile-soil interface are influenced by surface roughness of the pile, soil density, water content, freezing-thawing cycles, and stress levels, but with different degrees of sensitivity. Moreover, the proposed regression formula is able to predict the interfacial cohesion and friction angle of the wood-soil, concrete-soil, and steel-soil interfaces under different in-situ conditions.