A study on the correlation between soil thermal and electrical resistivity for HV cable route pre-design purposes

One of the main problems faced during the design of underground cable lines is associated with the determination of the soil thermal resistivity for cable sizing. Studying a new cable line route involves measuring soil thermal resistivity. The main complication arises from the fact that the momentary studies conducted generally may not indicate the real operation conditions, i.e. the sizing conditions may not be relevant. A methodology is required to convert the values measured to the possible extremes. The authors' pursuit of possible approaches to solve this problem involved the analysis of publications describing the existence of a significant correlation between soil electrical and thermal resistivity [1], [2]. The identification of a correlation between electrical and thermal resistivity would allow for obtaining the thermal resistivity for cable sizing using the already established methods for converting the electrical resistivity measured to relevant sizing conditions. The paper offers a review of other publications that deal with the problem and presents the experimental results obtained by the authors. The objective is to verify this correlation and study its applied value.