砂土场地排桩围护挡墙渗漏水对基坑变形规律的影响

针对富水砂层排桩挡墙渗漏水及基坑变形问题，以某地铁车站基坑工程为背景，采用数值模拟和现场实测方法对比研究砂土场地止水帷幕局部渗漏水前后基坑挡墙侧向位移、墙后地表沉降及围护桩墙内力变化规律。研究结果表明：止水帷幕局部渗漏加剧了渗流作用对基坑变形的影响，围护桩侧向位移曲线随基坑开挖深度的增大由“斜线”形向“鼓肚”形分布演变，墙后深层土体侧向位移曲线随水平距离L_p增大由非线性“鼓肚”形转变为线性分布；止水帷幕局部渗漏引起地表沉降量及影响范围增大，漏水后地表沉降显著影响区扩展为漏水前的2~3倍；围护桩身内力随基坑开挖深度增加而逐渐增大，漏水后桩身最大剪力和弯矩较漏水前减小；抑制渗漏通道扩展和阻止水土流失加剧是控制基坑渗漏灾害恶化的有效途径。研究成果可为砂土地区深基坑渗漏灾害防治与施工控制提供参考。

Effect of groundwater leakage of row-pile supporting structure on deformation rule of foundation pit in sandy soil site

In order to solve the problems of groundwater leakage of row-pile retaining structure and foundation pit deformation in water-rich sand stratum, based on the deep foundation pit engineering of metro station, the variation law of lateral displacement of retaining wall, ground settlement and internal force of retaining pile under curtain partial leakage in sand soil site are studied and compared by means of numerical simulation and field measurement. The results show that the curtain partial leakage exacerbated the effect of seepage action on the deformation of foundation pit, the lateral displacement curve of retaining pile develops from a oblique line shape to a parabolic shape with an increase of excavation depth, and the lateral displacement curve of deep soil develops from nonlinear parabolic shape to linear distribution with an increase of lateral distance L_p. The curtain partial leakage leads to the ground settlement and influence area increasing, and the significant influence area of ground settlement after groundwater leakage expands to (2.0~3.0) times of that before groundwater leakage. The internal force of retaining pile increases with the excavation depth''s increasing, and the maximum shear force and bending moment of retaining pile after groundwater leakage are lower than that of before groundwater leakage. It is an effective way such as blocked leakage passage and reduced soil erosion to control leakage disaster deterioration of foundation pit. The research results can provide reference for the hazard prevention and construction control during the groundwater leakage of deep foundation pit in sandy soil site.