Effect of test parameters on the recovery of underground after a Thermal Response Test and optimum waiting time between tests

Thermal Response Test (TRT) is an important method to determine the thermal properties of underground. These tests can be interrupted by unexpected reasons and a new test must be started in the same borehole, or the test must be repeated because of various reasons. In this paper, optimum waiting duration for a second test after a completed TRT is investigated through analyzing thermal behavior of a borehole during and after the test. A computational model is built, and it is verified with an experimental test. After the verification, the numerical model is used further parametric investigations. Different cases are considered and the results are discussed. The effect of thermal conductivity and test duration on the minimum waiting times are also investigated. It is shown that optimum waiting duration depends highly on the test conditions, however it varies between 10 and 23 days. • Thermal recovery of ground after a TRT and optimum waiting time is investigated. • The effects of different thermal properties on the optimum waiting time are investigated. • Optimum waiting duration based on test conditions varies between 10 and 23 days.