An Experimental Investigation of the Accuracy of Thermal Response Tests Used to Measure Ground Thermal Properties

This paper reports on the results of thermal response tests conducted with laboratory-grade instrumentation and equipment for a borehole system consisting of nine groundwater-filled boreholes, each about 80 m (262 ft) deep. The ground thermal properties, including the undisturbed ground temperature, the thermal conductivity and the borehole thermal resistance, are determined for each of the nine boreholes using standard evaluation methods. Comparison of the results of the ground thermal properties of the nine boreholes provides meaningful insight into the uncertainty issue of the thermal response tests. The ground thermal conductivity and the borehole thermal resistance estimations of nine boreholes are then used to investigate the sensitivity of the design of borehole systems to the random variations in the estimated thermal properties. The paper also presents the effects of the test duration and the heat injection rate on the estimated ground thermal properties when conducting thermal response tests.