Suction as an untapped natural soil reinforcement to reduce embodied carbon in geotechnical structures: the case study of flood embankments in Hamburg area

Abstract

The commitment to cut CO₂ emissions is now becoming a matter of legal obligations in several countries worldwide and the construction industry, one of the main sectors contributing to carbon emissions, is required to develop new approaches for carbon-efficient design. A study was undertaken to examine whether the inclusion of negative pore-water pressures (or ‘suction’) in the design of a flood embankment could reduce the embodied carbon associate with the construction of a new embankment or the retrofitting of an existing one. The case considered here are the embankments of the tidal Elbe area in Germany that require to be raised because of the new projection of extreme river levels due to climate change. Simple uncoupled water flow and stability analyses were considered to examine the performance of given embankment geometry. The purpose of the study is to examine whether incorporating suction into the design could allow for steeper landside slopes of the flood embankment. This would allow raising the embankment by saving considerable material and, hence, reducing the embodied carbon. At the same time, this would reduce the footprint of the raised embankment, which is a design requirement when flood embankments are embedded in the built environment as it happens in Hamburg.