落底式止水帷幕条件下临江深基坑渗流特性分析

Analysis of Seepage Characteristics of Deep Foundation Pits in Linjiang under the Condition of Bottom Sealing Curtain

为评估河道水位变化条件下基坑开挖及堤防工程的安全性,并提出防止渗漏破坏的防治措施和基坑开挖的合理方案,采用二维数值分析软件对临江深基坑开挖时渗流特性进行分析,计算表明:堤防现状渗流浸润线出溢点高程位于现状堤防坡脚,出溢点渗透坡降小于允许渗透坡降,满足要求;但进行基坑开挖后,若未进行止水帷幕施工,浸润线出溢点高程较高,出溢点渗透坡降较大,均不能满足渗流稳定要求;当设置落地式止水帷幕后,浸润线出溢点高程明显降低,出溢点渗透坡降明显减小,但河道设计水位下渗透坡降仍大于允许值。说明防渗帷幕能有效减小基坑开挖对该工程堤防渗流的影响。可考虑分区域分时段进行施工,以解决基坑开挖对渗流的不利影响。

In order to evaluate the safety of foundation pit excavation and embankment engineering under the condition of changes in river water level,and to propose prevention and control measures to prevent leakage damage and reasonable plans for foundation pit excavation,two-dimensional numerical analysis software was used to analyze the seepage characteristics of deep foundation pit excavation in Linjiang.The calculation showed that the elevation of the overflow point of the current seepage infiltration line of the embankment is located at the foot of the current embankment slope,and the seepage slope of the overflow point is smaller than the allowable seepage slope,meeting the requirements.However,after excavation of the foundation pit,if no water stop curtain construction is carried out,the elevation of the seepage line overflow point is high,and the seepage slope of the overflow point is large,which cannot meet the requirements of seepage stability.When a floor standing water stop curtain is installed,the elevation of the overflow point of the infiltration line is significantly reduced,and the infiltration slope of the overflow point is significantly reduced.However,the infiltration slope under the design water level of the river is still greater than the allowable value.The anti-seepage curtain can effectively reduce the impact of excavation on embankment seepage in this project.It can be considered to carry out construction in different regions and time periods during construction to address the adverse effects of excavation on seepage.