软土基坑围护结构水平位移控制措施

通过收集文献资料、概念分析和基于典型工程的定量计算,认为在控制围护结构水平位移的措施中,首道混凝土支撑能够避免由于轴力损失和地层预降水产生的桩顶位移,且投资增加较少,性价比较高,建议在软土基坑中优先选用;基坑内侧土加固控制基坑变形的效果很好,能减少围护结构的水平位移42%甚至更多,但投资增加较多,建议坑底以下为软土或变形控制标准较高时采用;增加围护结构截面尺寸对变形控制贡献有限,且投资较高,不建议优先选用,仅当其他控制措施无法达到设计要求时再考虑采用;增加基坑竖向支撑道数能够减少20%左右的围护结构水平位移,且投资增加幅度有限,建议变形要求较高时优先选用。

Analysis on the Horizontal Displacement Control of Supporting Structure in Soft Soil Foundation Pit

By data and conceptual analysis and quantitative calculation of typical engineering, following conclusions about the horizontal displacement control of supporting structures are reached: the first concrete support can avoid the top displacement of the pile due to axial force loss and pre-dewatering, and causes less investment increase, so it is cost-effective, and recommended to be used in priority for the soft soil foundation pit;It is very effective to control the deformation by strengthening the inner side of the foundation pit, which may reduce the horizontal displacement by more than 42%, however it will cost much, so it is suggested to be used while the soil under the pit bottom is soft or the requirements of deformation control standard are strict; The contribution to deformation control by increasing the cross section area of the supporting structures is limited, and will cause higher investment, so it is not recommended to be used in priority, merely be considered when the design requirements cannot be met by other measures. Increasing the number of vertical supporting structure can reduce the horizontal displacement by about 20%, and will not increase the investment much, therefor it is recommended to be used in priority when the deformation requirements are stricter.