Abstract

The behaviour and modelling of the contact zone between soil and structural elements - known as the interface - remain challenging for geotechnical engineers despite extensive study since Coulomb's fundamental work in 1776, which is widely used today. Difficulties arise from stiffness discontinuities and the inherently non-linear response of the interface, which, similar to the adjacent soil, depends on state variables such as relative density, stress state, loading history, and surface roughness of the structural element.

To capture this interaction realistically, the material behaviour of the soil is described by the subroutine UMAT, which is called in the subroutine UINTER, to describe the contact behaviour as a function of the normal and tangential deformations occurring. A novel shear strain evolution relationship is introduced to enable this coupling to accurately reproduce the stick-slip transition, considering surface roughness. In addition, the interface model couples volumetric and shear behaviour in the interface, capturing stress changes - jamming or unjamming - when the surrounding soil impedes volumetric strains.

Validation against experimental monotonic interface shear tests on dry granular soils using an advanced constitutive model confirms the ability of the framework to reproduce observed shear stresses, relative soil-structure displacements and normal stress variations. This approach allows realistic modelling of complex interactions in geotechnical systems and facilitates the simulation of interactions between different structural systems by incorporating the constitutive behaviour of the softer adjacent structure. The proposed framework significantly improves the predictive capability of interface models, providing a robust and reliable numerical tool for engineering applications.

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Presenter Bio

Michael Niebier was born in 1998 in Regensburg, Germany. After completing his Abitur, he pursued his studies at the Technical University of Munich (TUM), where he graduated in 2021.

Since then, he has been working as a research associate at the Center for Geotechnics at TUM. His research focuses on advanced geotechnical engineering solutions, with an emphasis on innovation and sustainability.