AN EXPERIMENTAL STUDY FOR INVESTIGATING THE INFLUENCE OF HYDROGEOLOGICAL ENVIRONMENT ON PARAMETER IDENTIFICATION BY THERMAL RESPONSE TESTS

Thermal response tests (TRTs) have been broadly applied to identify thermal properties of hydrogeo-logical environments. In order to quantitatively evaluate the effects of groundwater flow and level, water content on analyzed results of TRTs, TRT equipments for laboratory experiments were constructed so that groundwater level and velocity of seepage flow can be adjusted. Inverse analyses of experimental results were conducted first for cases under saturated conditions with negligible groundwater flow, and showed reasonable agreement of the identified thermal conductivities with those obtained from in-site TRTs conducted under the same geo-environmental conditions as the laboratory experiments. Laboratory thermal response experiments were further carried out for various conditions of seepage flow, groundwater level, water content, and it turned out that apparent thermal conductivities increase according as seepage flow velocity and/or water saturation increase. Furthermore, laboratory thermal response experiments conducted at a constant groundwater level for investigating to the influence of soil-water hysteresis lead to a conclusion that apparent thermal conductivities of soils under drying condition with higher soil water content are larger than those under wetting condition with lower soil water content.