ABSTRACT
The mechanical behavior of soil-structure interfaces is an influential factor in the load-deformation and the bearing capacity of almost all of geotechnical engineering problems such as retaining structures, reinforced soils, piles, under ground and offshore gravity structures. A number of experimental techniques have been suggested in the literature to study the mechanical behavior of soil-structure interfaces under different stress paths and stiffness boundary conditions. Among them, Ghionna & Mortara (2002) and Hu & Pu (2004) used direct shear tests, Zeghal & Edil (2002) employed ring shear apparatus, and Evgin & Fakharian (1996) used simple shear apparatus. On the other hand, considerable developments have been achieved in the field of constitutive modeling of interfaces. In this regard, Clough & Duncan (1971) suggested an interface model based on hyperbolic elasticity theory. Ghaboussi et al. (1973) suggested an elasto-plastic cap model for soil-structure interfaces. De Gennaro & Frank (2002) considered phase transformation and ultimate state in their elasto-plastic interface model. Ghionna & Mortara (2002) introduced a Cam-Clay type model for sand-structure interfaces. Recently, Liu et al. (2006) suggested that the Critical State Soil Mechanics concepts can be extended to include the mechanical behavior of interfaces. They also proposed a state dependent generalized plasticity interface model using the state parameter of Been and Jefferies (1985). More recently, Lashakari (2010) suggested a generalized plasticity interface model for sand-structure interfaces subjected to rotational shear.
