Constitutive rules of cyclic behavior of interface between structure and gravelly soil

We investigated the constitutive rules of cyclic behavior of the interface between a structure and gravelly soil using macro- and micro-observation results of a series of large-scale tests. Based on new understandings of the deformation mechanism, five constitutive rules of the cyclic behavior were described along with corresponding experimental proofs: (1) shear strength is proportional to normal stress. (2) Shear stress increases toward a stable value with increasing tangential displacement during the application of a monotonic stress path under constant normal stress condition. (3) Volumetric change due to dilatancy comprises reversible and irreversible dilatancy components. The reversible dilatancy component exhibits significant aeolotropical behavior. Only part of the tangential displacement contributes to the volumetric change due to dilatancy. (4) Compressibility decreases with increasing normal stress. (5) The evolution of the physical state, including particle-crushing and compression of the soil near the structure, causes and governs the evolution of the behavior of the interface and the evolution of the macroscopic stress–displacement relationship response of the interface.