A constitutive model for the gravelly soil-structure interface considering particle breakage and fabric change

Abstract

The isolated foundation with cushions is gaining popularity as a viable option for building bridges in active seismic zones due to its exceptional seismic isolation performance. However, the efficacy of this foundation relies heavily on the interactions within the cushion layer and between the caisson foundation and the cushion layer. The cushion layer, composed of 0.5 m thick crushed aggregate layer and 2.5 m thick pebble gravel, is susceptible to particle breakage and fabric change, which can significantly impact the overall behavior of the foundation. To better characterize the mechanical behavior of the cushion layer and the interface between aggregates and the structure, a new elastoplastic constitutive model is proposed in this study. The current model is built based on an existing constitutive model, Saberi’s model (Model-S). Two parameters are introduced, including a particle breakage coefficient, B10, calculated by total plastic work, and a fabric-dilatancy variable, z, to determine the interfacial dilatancy variation. The current model consists of 13 parameters in total. Comparison evident that the current interfacial constitutive model can better simulate the change of the physical state and asymmetrical response in the stress-displacement relationship due to symmetrical loading in different directions.