Abstract：In order to alleviate the contradiction between energy consumption and economic development in China, and adjust the national energy structure effectively, the government vigorously encourages to develop and use the green geothermal energy. Through the indoor test method and on-site thermal response experiment, the authors summarized the thermal conductivity characteristics and the influencing factors for different rock and soil. The results show that the thermal conductivity is in negative correlation with natural moisture content and porosity, and in positive correlation with natural weight and drying weight. The thermal conductivity is more affected by drying weight and porosity, and less affected by natural moisture content and natural weight. Through comparing the difference between the heating power and the thermal conductivity for the single and double U ground heat exchangers, the authors summarized that the comprehensive thermal conductivity of rock and soil in high power (6 000 W) is 10%~30% higher than that in low power (4 000 W). In the same power condition and the same site, the thermal conductivity for double U ground heat exchanger is about 30% higher than that for the single U ground heat exchanger. The utilization of double U ground heat exchanger can effectively reduce the hole depth and quantity. Through systematically analyzing the influencing factors of thermal conductivity of rock and soil, this paper provides statistical and theoretical support for geothermal energy exploration and evaluation. The results could promote the development and utilization of regional geothermal energy and be used for the construction of environment-friendly society.
2018, Vol. 5 
