Influencing factors of constant-temperature layer depth and its estimation in Shaanxi Province

The prediction of the constant-temperature layer depth is closely related to geothermal energy development and underground space construction. Progress of research on regional constant-temperature layer in Shaanxi Province is relatively slow. This paper discusses the influencing factors of the constant-temperature layer depth and the results show that there is an inverse correlation between the thermal conductivity and the constant-temperature layer depth. And the surface heat transfer coefficient between the surface and the atmosphere is positively correlated with the constant-temperature layer depth. Besides, the annual amplitude of the atmospheric temperature is positively correlated with the constant-temperature layer depth. The thermal conductivity coefficient and the constant-temperature layer depth showed a significant positive correlation. This paper describes and validates a method for calculating the constant-temperature layer depth. And the authors calculated the theoretical value of constant-temperature layer depth for different geomorphic units by using this method. The constant-temperature layer depth is between 10.5 m and 23.8 m for the whole province and is between 10.5 m and 23.8 m in northern Shaanxi Province, with 11~17.4 m in Guanzhong Basin and 11.7~18.6 m in southern Shaanxi Province. The depth range of the regional constant-temperature layer in Shaanxi Province has been systematically divided in this research and this paper has contributed to the implementation of Shaanxi’s “Green” Catch-up and Transcendent policies.