Abstract:

At present, in-situ thermal response test is widely used to measure thermal conductivity parameter in engineering. However, due to the lack of unified technical standard of the test, results obtained from in-situ test have unsatisfactory reliability. Our main aim is to analyze the effects of test methods and data processing on the results of the tests. Series of in-situ tests were carried out by using various of thermal response equipments in a special test well. Results show that in order to reduce experimental error, time interval between two thermal response tests should not be less than 10 days and circulating water should be prevented from heat exchange with other media(except for geotechnical media). For thermal response tests with steady input power, the value of thermal conductivity is positively correlated with times not used（1.0-12.0 h）. On the other hand, for thermal response tests with steady temperature difference, the thermal conductivity value  is negatively correlated with times not used (0.0-12.0 h).It is also found that the value of thermal conductivity is stabilized with times not used (>12.0 h). According to the uniform standard with times not used (>12.0 h), the values of thermal conductivity of the six units are all within 2.2-2.8 W/(m·℃), and the test results are reasonable and reliable.

Key words: ground source heat pump, in-situ thermal response test, soil thermal properties