内河深水暗流钢围堰施工关键技术研究

Research on Key Construction Technology of Steel Cofferdam in Deep Water Undercurrent of Inland River

以位于某铁路支线公路的L大桥为研究背景,研究内河深水暗流钢围堰施工关键技术。通过有限元建立该大桥钢围堰模型并设定模型条件,对钢板桩、土层相互作用以及河水水位上涨等展开拟合计算。依据水文地质参数及水流压强,计算钢围堰整体自重、静水压力、水浮力、流水压力等,将结果导入有限元模型,以模拟钢围堰施工过程,并清晰展现其中5种危险施工情况。试验结果表明,平衡前与平衡后土层位移最大值分别是8736 mm、2661 mm,该情况符合施工条件;钢围堰Y方向最大位移为76 mm,进行抽水与拆除支撑时位移增大,此时应加强施工安全警惕;钢围堰等效应力随静水压力增大而大幅度增加;钢板桩位移与水位成正比,水位上涨初期钢板桩位移与水位未上涨时相差不大,当水位上涨最高期时,钢板桩承受流水压力增大。

Taking L Bridge located in a railway branch road as the research area,the key construction technology of steel cofferdam in deep water undercurrent of inland river is studied.The steel cofferdam model of the bridge is established by the finite element method,and the model conditions are set.The steel sheet pile,soil interaction and river water level rise are calculated.According to the hydrogeological parameters and flow pressure intensity,the overall dead weight,hydrostatic pressure,water buoyancy and flowing water pressure of the steel cofferdam are calculated.The results are imported into the finite element model.The construction process of the steel cofferdam is simulated by this model.Five kinds of dangerous construction conditions are clearly displayed.The experimental results show that the maximum displacement of soil layer before and after balances is 8736 mm and 2661 mm respectively,which meets the construction conditions.The maximum displacement of steel cofferdam in Y direction is 76 mm.The displacement increases with pumping and removing support.At the moment,the construction safety should be strengthened.The equivalent stress of steel cofferdam increases greatly with the increase of hydrostatic pressure.The displacement of steel sheet pile is proportional to water level.The displacement of steel sheet pile in the initial stage of water level rise is similar to that when the water level does not rise.When the water level rises to the highest level,the steel sheet pile will bear increasing water pressure.