Research on Deformation Overlimit and Support Optimization of the Foundation Pit of Silt Soil Utility Tunnel
Aiming at the deformation overlimit of foundation pit in silt soil utility tunnel during the construction,combined with the actual engineering,Midas GTS finite element software was used to simulate the excavation and backfilling process of the foundation pit,and the consistency between numerical simulation results and field data was verified.Then,the deformation and the stress information of the pit were extracted and analyzed to propose a green support optimization method of frame double-row steel sheet pile+steel support.The results show that both the displacement and displacement rate exceed the warning value,and the displacement rate has more warning pre-cursor for the displacement overlimit;The uplift at the bottom of the foundation pit can better reflect the deformation state of the foundation pit;When the displacement reach 55％of the total increment,it is the most dangerous stage.The full-stage deformation of the steel sheet pile presents a'bow'shape.When the excavation completes,the defor-mation of the steel sheet pile is the largest at the position about 0.5H(H is the length of the steel sheet pile);The supporting structure of frame double row steel sheet pile+steel support is adopted to effectively controls the defor-mation of the foundation pit and the retaining structure.The deformation of the steel sheet pile is cantilevered after the support optimization.The displacement is controlled within 20 mm.The proposed frame double-row steel sheet pile+steel support structure can be recycled and reused to achieve green construction.The relevant research con-clusions can provide reference for similar projects.
foundation pit of the utility tunnelsilt soildeformation overlimitsupport optimizationsteel supportssteel sheet piles
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