多种围护结构在超大面积深基坑工程中的组合设计

超大面积深基坑工程周边环境条件多样,在满足基坑安全和环境保护要求的前提下,多种围护结构的结合应用更为合理和有效。本文以杨浦大学城一期基坑工程为背景,对采用“中心顺作、周边一明一暗顺逆作结合”的方法进行施工的基坑工程的围护结构设计进行了详细的介绍和分析。该工程采用了除型钢水泥土搅拌墙以外上海地区目前常用的所有围护结构形式,多种围护结构形式在基坑工程的整体设计中通过合理的平面组合和空间结合,在工程安全性、合理性、经济性等方面都发挥了更好的作用,为同类基坑工程的设计提供借鉴和参考。

Application of multiform retaining structures in large-scale deep foundation pits

The environment around large-scale deep foundation pits is mostly various.The foundation pit of first-stage construction project of Yangpu College community is such a project,which has an area of 25850 m2,a circumference of 773 m and a depth of 10 m.Except composite steel soil-cement mixed wall,all common retaining structures in Shanghai were used separately for excavation of shallow and deep part.According to different environmental protections,corresponding self-support retaining structures such as cement-soil wall,anchored steel sheet pile wall,complex soil nailing wall and slope were used for the excavation of shallow part.Then in the excavation of deep part,diaphragms were mainly used and piles in row were applied for the part which would be cut to conjunction with the second-stage project.With the protection of those retaining structures,all the soils above the B1 floor could be excavated directly.Then the peripheral B1 floor was formed,soil could be dug to the bottom and the structure was constructed normally from bottom to top in the central part.When the B1 floor was integrated,the soil slope below peripheral B1 floor could be dug out too.So the sequence of peripheral floor was constructed from top to down from B1 floor.The design could save the temporary bracing system and reduce volume of soil excavated below the floor,which was safe and economic.Different retaining structures were combined reasonably both in the plan and space,and it would provide a good reference to other similar projects.