In-situ and laboratory characterisation of stiff and dense geomaterials for driven pile analysis and design

Integrated field and laboratory characterisation of geomaterial behaviour is critical to foundation analysis and design for a wide range of offshore and onshore infrastructure. Challenges include the need for high-quality sampling, addressing natural and induced micro-to-macro structures, and applying soil and stress states that represent both in-situ and in-service conditions. This paper draws on the Authors’ recent research with stiff glacial till, dense marine sand and low-to-medium density chalk, and focuses particularly on these geomaterials’ mechanical behaviour, from small strains to failure, their anisotropy and response to cyclic loading. It considers a range of in-situ techniques as well as highly instrumented monotonic and cyclic stress-path triaxial experiments and hollow cylinder apparatus tests. The outcomes are shown to have important implications for the analysis of large driven piles under monotonic-and-cyclic, axial-and-lateral loading, and the development of practical design methods. Also highlighted are the needs for approaches that integrate field observations, advanced sampling and laboratory testing, numerical and theoretical modelling.