Abstract: The current research on cement-soil mainly focuses on its strength characteristics, while studies on the shearing mechanical properties of the cement-soil-structure interface remain relatively limited, which will restrict the promotion and application of cement-soil reinforcement technology in large-scale block foundations under horizontal loading. Thus, based on the self-developed large-scale interface shearing equipment, a series of shear tests and mechanistic studies on the cement-soil-concrete interface under repeated loading-unloading of variable normal stress mode and continuous normal stress loading mode have been performed, respectively. Moreover, based on the Mohr-Coulomb criterion, the formula for the minimum friction coefficient of the interface was derived.The results show that the solidification effect of cement-soil can significantly enhance the interface shear mechanical properties. The friction coefficient of the cement-soil-concrete interface gradually increases with the increase of curing time. The sliding shear plane can be remolded under pre-loaded normal pressure. As a result, the interfacial shear characteristics of a single specimen under cyclic loading-unloading modes are approximately equivalent to that of multiple identical specimens separately loaded. The shear behavior of the cement-soil-concrete interface under continuous normal stress loading will become weaker. Thus, in practical engineering, the shear performance of interfaces under such loading conditions should not be overestimated.

Key words: interface shear test, variable normal stress, cement-soil-concrete interface