Soil thermal and hydrological characteristics in designing underground cables

In the present paper, the thermal and hydrological characteristics of the soil surrounding buried cables are investigated. First, the dependence of the soil thermal resistivity on two easily measurable parameters is shown. These parameters are the porosity and the saturation degree. The soil hydrological stability is then investigated and is found to be governed by one hydrological parameter only; namely, the saturation degree. Finally, the conditions governing soil hydrological equilibrium are investigated, which appear to be dependent both on the initial soil saturation degree and on the applied thermal gradient (i.e. on the thermal flow). In principle, on the basis of this simple information, it is possible to carry out a rational design of a buried-cables system preventing any hydrological instability.