In-situ Monitoring of Deformation Laws of Deep Foundation Pit of Subway Station

Research purposes: The design of the exterior-protected construction and the study on the deformation laws of deep excavation are crucial to the construction of subway station,so it has the important value for construction to do the research on the deformation laws of deep foundation pit of subway station.Taking the deep foundation pit of the turn line station of the Olympic branch line of Beijing subway as the research bakground,the in-situ monitoring plan for deformation was designed according to the plan of excavation of the foundation pit and the plan of exterior-protected construction.Based on monitoring data,the monitoring data on the deformation and its basic laws of the retaining pile were analyzed,and the synergistic reaction of each part of the exterior-protected construction was researched on the base of the analysis of the load bearing of the steel support in combination with the deformation of the pile body. Research conclusions: With the increment of excavation depth and the application of steel support,the deformation state of the retaining pile gradually developed form the anteverted curve towards foundation pit to bow curve and the place of the maximum horizontal displacement also moved down.The horizontal deformation of the retaining pile and the axial force of the steel support increased with the increment of excavation depth.In fact,the monitored values were much smaller than the warning value,so the support scheme was conservative.