双排桩支护在软土地区基坑中的应用与分析

Application and Analysis on Double-row-piles Retaining Structure for Excavation in Soft Areas

双排桩支护作为一种悬臂式支护,为给排水厂站内泵房、水池等复杂构筑物深基坑的开挖和结构施工提供了极大便利。针对上海软土地区某大型泵房深基坑,本文进行了双排桩支护的应用和分析。通过弹性支点法计算和参数分析,在本工程中,桩径是影响基坑变形的主要因素,前后桩的合理排距可取3~4倍桩径,有限元分析表明,坑外地表沉降更接近于凹槽型分布曲线。通过现场实测分析,基于水土分算的弹性支点法计算所得的桩体变形能与实测结果更好地吻合。对于未封闭的双排桩基坑,建议在端部薄弱部位加强支护结构刚度。

As a cantilever excavation type,the double-row-piles retaining structure provides a great convenience for the excavation and construction in water supply and drainage engineering.In this paper,the doublerow-piles retaining structure was applied and analyzed in the case of large pump room deep excavation in soft soil area in Shanghai.According to the calculation and parameter analysis based on flexibility fulcrum method,it was found that the pile diameter was the main factor to reduce deformation in the soft soil area,a suitable pile row distance is 3~4 times of the pile diameter.It was found that the ground settlement was closer to the type of groove curve by finite element analysis.Through measurements and analysis,the pile deformation calculated by the flexibility fulcrum method based on estimating soil and water pressure separately matches with the measured results better.For unclosed double-row-pile wall,the weak region at the end is suggested to strengthen the supporting structure stiffness.