ANALYSIS OF THE THERMAL RESISTIVITY OF COMPACTED SILTY SOILS FOR DESIGNING UNDERGROUND CABLE SYSTEMS

This paper investigates the thermal conductivity of silty soils, when in compacted state. This aspect is especially relevant for designing underground electrical cables that are used to transmit energy from the sources to users. The high importance of the state of the soil is underlined by its role in the heat exchange efficiency, acting as a transfer medium between the electrical cables and the adjacent soil. The main approach of this paper is to review the grading size analyses of soils used for compaction and then, through laboratory testing methods to assess the thermal resistivity of the resulted material at different compaction states. The testing method employed for characterizing the material from the thermal resistivity standpoint is the thermal needle method, a method usually employed both on-site and in laboratory. The study examines silty soils with similar grading distribution and different compaction states, analysing their impact on thermal conductivity. The aim of this research is to establish the influence of the compaction state on the thermal resistivity of silty soils and, also, to offer some guidance in the choice of the soil used for filling the trenches dug for installation of cables.