Thermal Cone Penetration Test as a direct measurement of thermal conductivity of soils.

In situ measurement of the thermal conductivity of soils becomes relevant when laying structures which will dissipate heat. While the difference in thermal conductivity for different solids is relatively small compared to other physical properties, changes in porosity and soil consolidation will significantly change the effective thermal conductivity values. The goal is then not necessarily to perform a measurement with the objective of doing soil identification but as the means to understand the thermal conductivity properties locally, regardless of soil composition. Thermal data, along with industry standard measurements as described in ISO22476-1, can also be used to enhance the observable phase-space and thus improving discrimination capabilities. In this work, we introduce a new apparatus which can perform the in situ thermal conductivity measurement alongside industry-standard cone and piezocone penetration tests (CPTU) with unprecedented level of accuracy, while mitigating the impact of soil disturbances inherent to the cone penetration test.