富水地层深基坑支护结构插入比研究

Study on Insertion Ratio of Deep Foundation Pit Support Structure in Water Rich Stratum

基于淮安东高铁站站前广场大基坑,采用Midas软件建立三维数值模型,计算了八种不同插入比工况下,富水地层深大基坑的围护结构水平位移、坑外地表沉降、立柱桩最大弯矩值与围护结构外侧地下水流速的变化规律。结果表明:基坑围护结构水平位移曲线在不同插入比工况下,总体呈现中间大、两边小的横“山峰”形,当围护结构插入比大于2.1时,水平位移值变化开始趋于稳定;基坑开挖对地表沉降影响较大的范围是围护结构中间段往外5m到30m区域;插入比的增加可以减小止水帷幕外侧地下水流速最大值,从而减小支护结构受到的渗流破坏。

Based on the large foundation pit of the square in front of Huai'an East high speed railway station,a three-dimensional numerical model is established by using Midas software to calculate the variation laws of the horizontal displacement of the retaining structure,the surface settlement outside the pit,the maximum bending moment of the column pile and the groundwater velocity outside the retaining structure under eight different insertion ratio conditions.The results show that under different insertion ratios,the horizontal displacement curve of foundation pit retaining structure generally presents a horizontal"peak"shape with large in the middle and small on both sides.When the insertion ratio of retaining structure is greater than 2.1,the change of horizontal displacement begins to tend to be stable.Foundation pit excavation has a great impact on surface settlement in the area of 5m to 30m from the middle section of the retaining structure.The increase of the insertion ratio can reduce the maximum velocity of groundwater outside the water stop curtain,so as to reduce the seepage damage of the support structure.