软土深基坑非对称支护对邻近敏感结构变形的影响研究OA

To address the deformation control challenges of deep foundation pit adjacent to sensitive structures of bridges and pedestrian underpasses in soft soil areas,a combined support scheme of"asymmetric retaining structure+active servo control"was proposed and implemented based on a deep foundation pit project in Hangzhou.A 3D nu-merical model was established using the finite element software Plaxis 3D.The HSS model was employed to simulate the small-strain stiffness characteristics of the soft soil,and the entire construction sequence including excavation of Stage Ⅰ →backfill → excavation of Stage Ⅱ.The results indicate that the asymmetric retaining scheme of utilizing diaphragm walls with three supports of struts on the west side near the bridge and bored piles with three upports of struts on the remaining sides,combined with active axial force servo compensation,can precisely control over envi-ronmental deformation;The maximum horizontal displacement of the retaining structure is 7.5 mm,and the maxi-mum ground settlement outside the pit is 14.3 mm,exhibiting a narrow and deep settlement trough;Furthermore,the maximum horizontal and vertical displacements are 1.63 mm and-0.78 mm for the adjacent bridge pier,and the maximum horizontal and vertical displacements are 1.14 mm and-1.06 mm for the pedestrian underpass,respec-tively.All are well within the strict control limits(bridge≤ 3.0 mm,pedestrian underpass≤5.0 mm).The additional deformation of the retaining structure caused by Stage Ⅱ excavation is approximately 30％～40％of that by Stage Ⅰ,because that the partition piles effectively mitigate the superposition effects of staged construction on sensitive struc-tures.This scheme provides a valuable technical reference for similar deep foundation pit projects in complex and sensitive urban environments.