Objective To meet the deformation control requirements of foundation pit excavation in complex urban environments, newly constructed foundation pit projects often adopt servo support systems. However, current analysis of the deformation control performance and influencing factors of servo steel supports remain incomplete, which restricts the effectiveness of servo steel support applications. Therefore, it is necessary to study the deformation control effect and influencing factors of servo steel supports based on model tests.

Method A 1:20 scale servo-support foundation pit model test is designed to conduct a comparative analysis on the supporting performance of servo supports and conventional supports. The influence of servo axial force application timing on the deformation control is examined, and the effects of factors such as excavation depth and combinations of support levels on the stress and deformation behavior of the retaining structure are further investigated.

Result & Conclusion  Adjusting the servo support axial force during the excavation process yields better performance than adjusting it after excavating completion. At different excavation depths, deformation control effect achieved by adjusting two levels of support is superior to that by adjusting a single level of support axial force. Adjustments to servo support axial force may lead to a redistribution of earth pressure behind the wall, and the magnitude of earth pressure redistribution varies depending on the adjustment at different support positions ; adjustment at the lowest support level may induce the most significant redistribution of earth pressure.