逆作法地下结构超大超重桩柱一体化精准施工研究

Research on High-Precision Construction Method for Integrated Construction of Super-Large and Super-Heavy Pile-Column in Reverse Underground Structure

北京城市副中心交通枢纽为超大深基坑工程,采用逆作法进行桩柱一体化施工,桩柱的体积大、重量重、施工困难,但是又要求高精度施工。其中,对桩的施工精度要求达到桩位偏差不超过20 mm,桩身垂直度不超过1/300;对柱的施工精度则具有更高要求,柱定位轴线偏差不大于1.0 mm,垂直精控制在1/800~1/1000。本文通过对现场施工方法的研究,发现:①用逆作法进行桩柱一体施工的施工工艺,可以满足精度要求;②桩施工部分要重点从桩位定位及桩身垂直度两方面进行控制,钢管柱施工部分要重点从柱定位、柱身垂直度和柱顶标高沉降三方面进行控制;③采用HPE工法插入钢管柱,需要利用全站仪及倾斜传感器进行辅助监测以保证质量。

The Beijing City Vice Center Traffic Hub is a super large and deep foundation pit project.The top-down construction method is adopted for the integrated construction of piles and columns.The piles and columns are large in volume,heavy in weight,and difficult to construct.Thus,high-precision construction is required.The pile position deviation should not exceed 20 mm,and the verticality of the pile body should not exceed 1/300.For the construction of the column,there is even more higher requirements for the accuracy,that is,the deviation of the column positioning axis is not more than 1.0 mm,and the vertical precision is controlled at 1/800~1/1000.Through the study on the method at the construction site,this paper found that:①The accuracy of the construction method of the integrated pile-column construction with the top-down construction method can meet the requirements.②The pile construction part should focus on the positioning of the pile and the verticality of the pile body.In the construction of steel pipe columns,the control should focus on three aspects:column positioning,verticality of the column and the elevation and settlement of the top of the column.③The use of HPE construction method inserted to the steel column requires the use of a total station and tilt sensor for auxiliary monitoring to ensure quality.