Abstract: Geothermal heating/cooling systems can effectively work towards the UK decarbonisation goal, effectively contributing towards the sustainable development goals. Although geothermal structures have been widely deployed, little attention towards the thermal effect on granular soils has been given in the literature. What is even more surprising is the lack of standard protocols to perform tests, interpret data, and determine acceptable uncertainties while performing temperature-controlled tests.
A bespoke triaxial cell (MKII) was developed at Imperial College London to accurately measure hydraulic conductivity and thermally-induced mechanical (TIM) strains of granular geomaterials at different temperatures. Characterising the thermal performance of the different components of MKII is crucial to guarantee its performance. As a consequence, non-isothermal and isothermal calibrations protocols for the MKII cell will be presented and critically assessed. Detailed protocols of how to proceed with tests and further interpretation to obtain meaningful results will be also discussed. Obtaining meaningful results was extremely challenging, but it is believed that such transparency associated with robust protocols could lead to significant improvements of the quality of results that are generated.