In Situ Determination of Thermal Resistivity of Soil : Case Study of Olorunsogo Power Plant, Southwestern Nigeria

Abstract EN

This study measured in situ the thermal resistivity of soils at Olorunsogo Gas Turbine Power Station (335 MW Phase 1) which is located in Ogun State, Southwestern Nigeria.

Ten pits, each of about 1.5 m below the ground surface, were established in and around the power plant in order to measure the thermal resistivity of soils in situ.

A KD 2-Pro was used for the in situ measurement of thermal properties.

Samples were also collected from the ten pits for laboratory determination of the physical parameters that influence thermal resistivity.

The samples were subjected to grain size distribution analysis, compaction, specific gravity and porosity tests, moisture content determination, and XRD analysis.

Also, thermal resistivity values were calculated by an algorithm using grain size distribution, dry density, and moisture content for comparison with the in situ values.

The results show that thermal resistivity values range from 34.07 to 71.88°C-cm/W with an average of 56.43°C-cm/W which falls below the permissible value of 90°C-cm/W for geomaterials.

Also, the physical parameters such as moisture content, porosity, degree of saturation, and dry density vary from 13.00 to 16.20%, 39.74 to 45.64%, 40.72 to 63.52%, and 1725.05 to 1930.00 Kg/m3, respectively.

The temperature ranges from 28.92 to 35.39°C with an average of 32.11°C in the study area.

The calculated thermal resistivity from an algorithm was found to vary from 48.43 to 81.22°C-cm/W with an average of 65.56°C-cm/W which is close to the thermal resistivity values measured in situ.

Good correlation exists between the in situ thermal resistivity and calculated thermal resistivity with R=+0.85 suggesting that both methods are reliable.