滨海地区砂质粉土地层深大基坑工程设计与施工

Design and construction of deep and large foundation pit engineering in sandy and silty soil layers in coastal areas

岩土特性对于深大基坑工程设计与施工有重大影响。针对砂质粉土透水性强等技术难题,以上海临港新城某深大基坑工程为例,综合考虑水文地质等因素对基坑围护设计方案进行了详细比选,提出了SMW工法桩加上南北、东西2个方向设置钢筋混凝土支撑的方案,采取工法桩穿透淤泥质黏土隔绝外部水力联系、提前进行基坑降水到坑底以下1 m以及加强水位与深部位移监测等措施,并运用结构计算软件对施工方案进行了复核。工程应用表明,基坑施工过程安全可控,围护桩位移与地面沉降等均满足相关规范要求,该支护结构方案合理有效。相关结论可为类似深大基坑工程设计施工提供理论指导与技术支撑。

The geotechnical characteristics have a significant impact on the design and construction of deep and large foundation pit engineering.In response to technical difficulties such as strong permeability of sandy silt,taking a deep and large foundation pit project in Lingang New City of Shanghai as an example,a detailed comparison and selection of foundation pit enclosure design schemes was carried out in comprehensive consideration of hydrogeology and other factors,and a scheme of SMW construction method piles with reinforced concrete support in the north-south,and east-west directions was proposed,and the measures were adopted including using construction piles to penetrate through silty clay to isolate external hydraulic connections,pre dewatering the foundation pit to 1 m below the bottom,and strengthening monitoring of water level and deep displacement.And then the construction scheme was calculated and reviewed using structural calculation software.Engineering applications have shown that the construction process of foundation pits is safe and controllable,and the displacement of retaining piles and ground settlement meet the requirement of relevant specifications.This support structure scheme is reasonable and effective.The relevant conclusions can provide theoretical guidance and technical support for the design and construction of similar deep and large foundation pit projects.