Abstract: The deformation control in the deep excavation in the soft soils is critical, especially, near the shielded tunnel and other complex environment. Based on the deep excavation project of an open cut tunnel in soft soils in Hangzhou City, this paper presents a case history of Wenyi West Road area. The deformation control measures and results are evaluated by the combination of both numerical analysis and construction monitoring results. The results show that: (1) the maximum horizontal displacement of the support structure can be significantly reduced by preloading the supporting axial force on the support structure. At the same time, with the increase of the preloading axial force, it also has an obvious control effect on the surface settlement. (2) In the process of excavation, the support servo system has a significant effect on the deformation control, which can effectively control the horizontal deformation of the support structure, reduce the surface settlement, and help reduce the impact on the surrounding environment.

Key words: Deep Excavation, Deformation Control, Preloading Axial Stress, Servo System