Aiming at the thermal attenuation problem of ground temperature field in unidirectional heat extraction and supply in buildings of deep-buried geothermal energy, we propose supplementing heat to the ground using some heat source such as solar energy that is stored during the non-heating period, thus enabling long-term operation of a buried pipe system. With the study conducted on a buried U-bend pipe project with a depth of 2505 m, a three-dimensional (3D) full-scale model was established based on the numerical modeling method which obtained by the author's research team in the early stage. The heat extracted from the buried pipe or the heat storage capacity of ground for a constant inlet water temperature and given initial ground temperature field was analyzed and predicted. Meanwhile, the heat storage capacity after heat was taken from the buried pipe was calculated and analyzed. Finally, heat flux through the wall of the buried pipe was analyzed, and heat transfer to ground at different buried depths during the heat storage period was discussed. (c) 2020 Elsevier Ltd. All rights reserved.