Periodic Reporting for period 2 - TERRE (Training Engineers and Researchers to Rethink geotechnical Engineering for a low carbon future)
Reporting period: 2017-11-01 to 2019-10-31
TERRE targeted the geotechnical construction industry, a major component of the overall construction sector, which is strategically important in infrastructure development (transportation, flood and landslide protection, building foundations, waste disposal). This project explored novel design concepts for low-carbon geotechnical infrastructure through 15 PhD projects carried out by ESRs who were ‘trained through Research’ in low-carbon design. Design concepts included eco-reinforced geomaterials, binders ‘recycled’ from waste, ‘engineered’ vegetated and bare ground-atmosphere interfaces, shallow geothermal energy, and shallow soil carbon sequestration.
Many PhD research projects were oriented towards a potential technological application in their later stage by involving industrial full and associated partners. This synergy between industry and academia ensured that the research remained problem-driven and that the fundamental research had a tangible social, environmental, and economic impact.
TERRE recognised that fundamental concepts concerning greenhouse gas emissions, carbon sequestration and, more generally, sustainable development are often not addressed in higher education in civil engineering. TERRE addressed this knowledge gap by organizing annual Schools to help rethink civil engineering design. These were mainly designed for early-stage researchers but were of equal benefit to established researchers and practitioners in the civil engineering field.
NOVEL MATERIALS FOR CARBON-EFFICIENT GEOSTRUCTURES
a) A feasibility study to investigate the use of alkaline-activated fly ash as binder for soil stabilisation has been completed successfully.
b) A field scale experiments have been designed and carried out to investigate the use of timber sheet pile walls in combination with riparian vegetation to stabilise river and canal banks.
c) Two experimental programmes to investigate the feasibility of bio cementation to stabilise earthen construction materials (using biopolymers and enzyme-induced calcite precipitation respectively) have been completed successfully.
DEVISING INTERFACES FOR CARBON-EFFICIENT GEOSTRUCTURES
d) Two field trials in Italy and Spain have been set up to investigate vegetation effects on natural and man-made slopes respectively. In addition, a new techniques to monitor xylem water potential (as an indicator of the efficiency of evapotranspiration in generating suction) has been developed
e) A mock-up scale laboratory experiment has been designed and constructed to investigate the use of engineered soil-atmosphere ‘sandwiched’ physical interfaces to maintain suction in the ground.
f) A study has been completed on the role of environmental factors (i.e. temperature and soil moisture) on growth of fungal mycelia (to protect riverbanks and flood embankments from erosion). A tensile test for determining shear characteristics of soils strengthened by fungal mycelia has been developed and resistance to erosion tested in a jet-erosion apparatus.
GEOSTRUCTURES FOR ENERGY/CARBON CAPTURE AND STORAGE
g) Design criteria for shallow geothermal structures have been developed based on the analysis of the case study of a metro tunnel station with walls and raft equipped with geothermal pipes.
h) Mock-up scale experiments to investigate different Carbon input in soils (depending on different plant species used in earth embankments) have been developed. Data on the relationship between root dynamics and Carbon stored in different fractions of soil have been obtained.
OPERATIONAL AND DESIGN TOOLS
i) Criteria for Life Cycle analysis to assess economic and environmental impact have been defined for suction-reinforced geo-structures.
j) An optimisation algorithm was developed to be implemented in ultimate limit state design software for minimum energy/carbon.
The construction sector has been investing significantly in research to produce innovative low-carbon technologies, including low carbon concrete, low carbon steel, and energy building efficiency. However, there has been little innovation in the geo-infrastructure field, which is lagging behind other sectors of the construction industry. TERRE aimed at closing this gap by creating a multi-disciplinary and inter-sectoral network to impact the way of thinking of geotechnical engineers. This network was unique in the area of geo-infrastructure and was complementary to several other networks funded by the European Commission under FP7 on low-carbon infrastructure.
RESULTS ACHIEVED AT THE END OF THE PROJECT
- Methods for low-impact stabilisation of geo-materials based on alkaline activation of fly ash (for efficient use of marginal soils)
- Methods for designing bio-based soil reinforcement to stabilise man-made slopes (without the use of concrete or steel)
- Methods for manufacturing bio-based earthen construction materials (stabilised using bio-polymers or enzyme-induced calcite precipitation)
- Methods for stabilising geo-infrastructure using engineered bio-interfaces (including plants and fungal mycelia)
- Criteria to design engineered soil-atmosphere sandwiched interfaces for ‘climate enhanced’ geo-infrastructure
- Criteria to design of geothermal energy exchanger embedded into conventional shallow geotechnical structures
- Methods for enhancing carbon sequestration and storage by vegetation in new earthfills
- Procedures for carbon footprint assessment of geotechnical construction
- Software for ultimate limit state design of geo-infrastructure incorporating optimisation tool for minimum energy/carbon
There is still a gap between research and practice in low-carbon design, particularly in civil engineering. By the end of the project, all recruited researchers have received excellent training at the interface between Industry and Academia. Collaboration between industrial and academic partners was embedded within the project through the mechanism of ‘Industrial’ PhDs and, for the ESRs involved in ‘Joint-award’ PhDs, through the programme of secondments to industrial partner organisations. It is therefore expected that the ESRs will be able to secure jobs where the interplay between Academia and Industry is the key focus.
TERRE aims to create a permanent school on ‘Low carbon design of geo-infrastructure’ with the ESRs expected to contribute to the School scientifically.