Towards recommendations for owners and geotechnical designers for adaptation of geotechnical structures to climate change

Almost all existing or planned geotechnical structures will have to cope over the coming decades with changes in the climate, whether gradual or sometimes sudden, which may have consequences ranging from a few disorders to the failure of the structure. Some questions need to be asked to adapt our civil works to these unprecedented changes. How does the climate change alter the properties and mechanical behaviour of soils? Where to find information on sea-level rise or climate projections for designing structures? Which of the IPCC scenarios can or should be considered? What effects might affect a road, a railway, a house, the foundations of an engineering structure, a retaining wall, or a coastal structure? How can we assess the vulnerability of existing structures and make them more resilient? What adaptation solutions are possible for each type of structure? How to make the design, keeping in mind that the climatic actions considered today will be obsolete in a few decades? To answer these questions, a working group (WG) called Geotechnics and Climate Change was launched in France in 2022 by the CFMS (French Society for Soil Mechanics and Geotechnics) and the CFGI (French Society for Engineering Geology). A Part of this WG, the Sub-Group 2, made up of around twenty members from the French geotechnical community, has been specifically dedicated to the adaptation of geotechnical structures to the effects of climate change, with the aim of drafting recommendations for owners and designers of geotechnical structures. The purpose of this paper is to describe the scope of the working group and to present the key points of the future recommendations, that will be published soon: reference scenarios and climate projections in France, effects of climate change and impacts on different types of structures, principles of adaptation strategies and design considerations.