Geofisica Misure s.n.c.

Geophysical surveys and monitoring of land and artifacts.

Measurements of thermal resistivity

Measurements of thermal resistivity of soils are realized in order to assess what are the characteristics of heat conduction. The specific parameter is the thermal resistivity or its inverse, called thermal conductivity.

The data is very useful in the design of underground cable ducts, in order to evaluate the temperatures induced in the conductors or to evaluate the dispersion of heat in the pipes of geothermal plants.

The measurement method is based on the technique of so-called non-stationary sensor, which uses a probe (also called thermal needle), which incorporates both a heating wire, that a temperature sensor. The probe is inserted into the ground, by its response to a heating cycle during few minutes,it is possible to calculate the thermal resistivity (or its inverse, the conductivity).

The principle of measurement is based on a peculiar characteristic of a rectilinear heat source (the heating wire of the probe): after a brief transitional period, the temperature rise depends only on the heating power and the thermal conductivity of the medium. Note the first is then possible to calculate the second.