Designing for the Future: Optimising the structural form of regolith-based monolithic vaults in low-gravity conditions

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This project will investigate the behaviour of monolithic, adobe structures in low-gravity conditions, concluding to an optimal structural design framework for supporting future space exploration. Such structures will act as shielding to protect critical assets (such as robots, fuel tanks and power stations) and future inflatable structures (e.g. living quarters) from extreme conditions (radiation, sandstorms, temperature fluctuations) in an extraterrestrial environment. Linear and nonlinear numerical structural modelling and parametric static and dynamic analyses will identify the optimal design approach for utilising indigenous materials to produce such structures to minimise the weight burden on future manned explorations. The analytical work will be validated by experimental centrifuge tests which can simulate low gravity conditions at prototype scale. This will be the first systematic approach towards sustainable extraterrestrial structural design using methods and concepts developed for Earth. Until now, there have been isolated studies on conceptualising extraterrestrial structures given the challenges that needed to be addressed in such extreme environments, but there is not a systematic approach on how to realise these structures. Given the recent and ongoing research on the mechanical properties of regolith simulants, the proposed In-situ Resource Utilisation (ISRU) framework and the advances in 3D printing for extraterrestrial construction, it is timely to combine these fields with structural design strategies developed for Earth in order to identify optimal structural forms for use in low-gravity conditions, subject to extraterrestrial dynamic environmental actions. The first step for achieving this is the static approach and to identify from a wide class of monolithic vaults which is the optimal for long-span structures in low-gravity environments. The next step would be to identify engineering demand parameters from extraterrestrial natural hazards related to Lunar and Martian strong ground motions (shallow and deep moonquakes, marsquakes if available from the InSight mission and meteorite-impact generated ground motions). Subsequently, numerical models simulating different structural dynamic configurations (including soil-structure interaction, rocking and seismic isolation) will be implemented to conduct extensive linear and nonlinear dynamic analyses using the identified engineering demand parameters. This will result in the assessment of the dynamic performance of each different model and thus to the best structural option. However, a critical part is to validate the numerical models used in this project by centrifuge tests under the same extraterrestrial excitations. Nevertheless, it is out of the scope of this project to investigate the properties of regolith-based structural material since regolith simulants will be used for the experimental part of the project. The main benefit of this project is the establishment of a rigorous structural design framework regarding extraterrestrial structures and the identification and categorisation of the extraterrestrial strong ground motions as a first step for the quantification of the associated hazard. Aside from the aforementioned objectives related to space exploration and multi-planet colonisation, the potential applications of the results from this project can be: (a) the calibration and development of 3D-printing techniques incorporating regolith as a structural material; (b) the sustainable residential development of low- and middle-income countries using indigenous materials and (c) the optimal seismic design of submarine structures (arches in a global compression state under buoyancy/low gravity) that can prove useful for deep-ocean exploration and mining.