<p>This study focuses on Thailand’s first power tunnel freezing repair project in Bangkok. Thermal property parameters of the soil strata needed for analyzing the safety of the frozen curtain were lacking. To address this, the study employed, for the first time, the TPS and TLS methods to investigate the evolution of thermal conductivity in local ground layers (including CH, CL and SM) across unfrozen, phase change, and frozen zones. A comparative analysis of the applicability of the two methods was also conducted. Experimental results indicate that thermal conductivity of the same soil is highly temperature-dependent, increasing by approximately 50 % in the frozen zone and 30 % in the phase change zone compared to the unfrozen zone. Sandy soils exhibit better thermal conductivity than clay due to the higher content of thermally conductive minerals. The Hot Disk, with its rapid response capability, is more suitable for capturing thermal conductivity variations in the phase change zone, while the KD2 Pro excels in steady-state measurements and is better suited for soils with limited moisture migration. Recommended values for the thermal conductivity of typical Bangkok soils are proposed. Additionally, a field-scale coupled hydrothermal model was developed, and the results from three different thermal conductivity models—measured, fixed, and geometric mean—were compared. The comparison demonstrated that the measured thermal conductivity model more accurately simulates variations in the temperature field. This research provides key thermal parameters for simulating temperature fields in tropical artificial ground freezing projects and offers a scientific basis for the optimized design of frozen curtains under similar geological conditions.</p>