Study on the dewatering feasibility and water blocking effect of thin soil interlayer as the bottom layer of cofferdam
[Objective]In order to explore the precipitation feasibility and water blocking effect of the underwater sand layer with thin soil interlayer as the bottom layer of the pier cofferdam,[Methods]FLAC3D was used in this paper to simulate and analyze the entire construction process of the concrete bottom sealing cofferdam and the thin soil interlayer bottom sealing cofferdam,and analyzed the thickness of the thin soil interlayer,the permeability coefficient,the continuity,the length of the steel pipe pile,the distance between the top of thin soil interlayer and the bottom of the steel pipe pile,steel pipe pile and concrete cushion thickness variation on horizontal deformation of steel pipe pile,uplift deformation of pit bottom and seepage of pit bottom.[Results]The result show that the steel pipe piles reach the maximum horizontal deformation at 14 m below the pile top in the completion stage of the main pier of cofferdam with and without thin soil interlayer,and the deformation is 16.36 mm and 20.72 mm respectively,which both meet the requirements of the code.When the thickness of the thin soil interlayer is 4 m,the permeability coefficient is 5×10-9 cm/s,the horizontal span of the thin soil interlayer is 55 m,the length of the steel pipe pile is 40 m,the distance be-tween the top of the thin soil interlayer and the steel pipe pile is 0 m,and the thickness of the concrete cushion is 3 m,the water resistance of the thin soil interlayer is the best.[Conclusion]Thin soil interlayer has good permeability resistance,and it is fea-sible to use it as the bottom layer of cofferdam seal for dewatering construction,and relevant research result can provide reference for similar projects.
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