Abstract: The construction of large-scale foundation pit systems in soft soil strata necessitated the implementation of comprehensive design approaches and advanced construction control techniques to ensure structural safety, timely project completion, and effective deformation management, while minimizing cumulative environmental impacts on surrounding areas. Effectively controlled deformation and reduced the superimposed impact on the surrounding environment. Combined with the practical experience of super-large scale foundation pit in soft soil area, the design method and deformation control technologies of foundation pit group engineering were systematically expounded. It included setting single partition wall skip excavation method, setting buffer-zone symmetrical excavation method, micro-deformation control method of foundation pit group considering sensitive environmental protection. Through the setting of partition walls or buffer zones for zoned excavation, while meeting the development progress requirements of different plots, the influence degree of the space-time effect and the mutual influence between the divided zones could be effectively controlled. When a large-scale group of foundation pits was adjacent to a sensitive environment, according to the size of the adjacent zoned foundation pits, the dynamic adjustment of foundation pit deformation could be achieved by adopting steel strut with automatic axial force compensation system and concrete strut with servo system. Combined with typical engineering cases, it was proved that the above design method could achieve good economical and technological effect of deep excavation group.

Key words: deep excavation group, soft soil, cumulative impact on the environment, zoned design method, deformation control