English：

To address the challenge of deformation control during the installation and demolition of internal support in deep foundation excavation under complex conditions, this paper uses a largescale deep foundation excavation project in the city of Hangzhou as a case study. A threedimensional integrated computational model was established using finite element software to analyze the impact of construction and demolition plans on excavation stability. The sequence of internal support installation and demolition was optimized through technical measures such as basintype excavation, zonebyzone construction and demolition, control of trestle loads, and wire saw cutting. The results indicate that the zonebyzone symmetrical demolition method effectively controls foundation excavation deformation. Monitoring data show that all indicators remain within the designallowed limits, ensuring the safety of the foundation excavation and the surrounding environment.