Characterisation of geotechnical properties for whole-life design

Abstract

Loading events during the life of a structure affect the geotechnical engineering properties of the soil that the structure is constructed on or in, which in turn affects the response of the structure to any future event. Understanding the changing soil properties over the design life of infrastructure is essential for safe and efficient design. These concepts are encapsulated in an emerging ‘whole-life’ geotechnical design approach that accounts for evolving soil properties through the design life of a structure by coupling time-varying actions and the evolution of soil resistance to create a continuous assessment of the performance of a structure.
For fine-grained soils, whole-life geotechnical response is driven by generation and dissipation of excess pore water pressure, leading to episodes of softening and hardening through the life of the structure. Whole-life geotechnical response in fine-grained soils have been observed and quantified through geotechnical centrifuge modelling, element testing and numerical modelling, and in cases generalised through Critical State Soil Mechanics principles. However, for a framework of whole-life geotechnical design to be used in routine practice, an efficient and effective method of characterising the evolving geotechnical properties of a soil to actions over the design life of a structure is required.
This research has employed laboratory element testing and finite element analysis to describe evolving geotechnical properties of a soft natural clay under whole-life loading, comprising episodes of monotonic and cyclic pre-failure loading with intervening consolidation. A theoretical interpretation, that forms the basis of a new framework that can be adopted for whole-life geotechnical design is presented.
Enhancing geotechnical design to contribute to offshore wind ambitions globally was the motivation for this research, such that load paths adopted in the laboratory testing and numerical modelling, and the hypothetical case study to demonstrate the theoretical framework, were based on offshore scenarios.
However, the principles of whole-life geotechnical design and the proposed theoretical framework are equally applicable to a range of geotechnical engineering applications, offshore and onshore.

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Identifiers

ORCID for Noor Laham: orcid.org/0000-0001-8289-149X

ORCID for Susan Gourvenec: orcid.org/0000-0002-2628-7914

ORCID for Dave White: orcid.org/0000-0002-2968-582X

ORCID for Katherine Kwa: orcid.org/0000-0002-4675-8736

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