A micro-mechanical study for soil-structure interfaces

his research project aims to address the current shortcomings in knowledge related to the constitutive behaviour of soil-structure interfaces. This will be achieved by undertaking a programme of element scale interface tests in order for different influencing parameters to be investigated. In addition to traditional stress-strain results, individual soil grains at the interface will be monitored during shearing using advanced photography capture and analysis methods. Analysis of changes in the soil grains and interface surface will be also be investigated using standard and scanning-electron microscope methods. By taking a micro-mechanical approach, the fundamental mechanisms influencing the macro-scale stress-strain behaviour will be determined and understood.

Based on this established micro-mechanical understanding, an analytical model will be developed which encapsulates the observed behaviour in an academically rigorous manner. It is important that this model is not derived from empirical fitting to the obtained experimental data, as to do so would limit the model to being validated solely for the soil and interface types tested. This limitation is common in research already published. By understanding fundamental mechanisms and building on fundamental theories, the resulting model will be applicable to a wide range of scenarios. Such an interface model would then be able to be fed into simulations of overall soil-structure-interaction systems, hence eliminating the current simplification made when conducting such simulations.

The initial work within this project will focus on understanding and developing a model for monotonic behaviour which, one validated, will be built upon to develop a cyclic loading model. There are numerous challenges associated with cyclic loading including: increased degradation of the interface material, disruption of force chains through the soil and cyclic compaction of the soil body. Therefore the model will require several additional factors to be added to capture each of these effects, significantly adding to the complexity and advancement of the model.