摘要
新建工程上穿施工卸载导致下卧地层及既有地铁结构发生上浮变形。相比于下穿施工的超前预加固、千斤顶顶升、桩基托换等成熟且有效的变形控制技术,目前上穿施工引起既有结构的上浮变形尚未有较好的控制及恢复方法,是工程界亟需解决的问题。本文以北京某框架桥上穿既有地铁盾构区间工程为背景,基于案例搜集明确了当前上穿工程主要采用注浆加固和拉锚等辅助措施、既有结构实测上浮变形介于1.90~15.59 mm、新建工程开挖断面越大及既有结构纵向刚度越小则既有结构上浮变形越大的规律;采用理论分析提出了"应力平衡顶推法",并制定了"力平衡,短进尺,勤量测"的施工控制措施;通过三维有限元计算,与压顶法和明挖法进行了对比,应力平衡顶推法引起既有隧道最大上浮变形最小(0.5 mm),是明挖法和压顶法的10%和12%。工程实际应用后,既有隧道实测累计最大上浮0.6 mm,为上穿工程提供了一种新的微变形控制方法。
The unloading of the construction of the new project leads to the floating deformation of the underlying stratum and the existing subway structure.Compared with the mature and effective deformation control technologies such as advance pre reinforcement,Jack jacking and pile foundation underpinning of Underpass construction,there is no better control and recovery method for the floating deformation of existing structure caused by undercrossing construction,which is an urgent problem to be solved in the engineering field.In the case of 4 overcrossing projects in Beijing area,the new projects use undermining method,supplemented by grouting reinforcement,pulling anchor and other auxiliary measures.The measured floating deformation of the existing tunnel is between 1.90 mm and 15.59 mm.The larger the excavation section of the new project and the smaller the longitudinal stiffness of the existing structure,the greater the floating deformation of the existing structure.The"stress balance lifting method"is put forward.The core of this method is counterweight jacking.Taking the"balanced power,short footage,frequent measure"measures to reduce the disturbance on land.Through three-dimensional finite element calculation,it is compared with the jacking method and open excavation method.The largest floating deformation caused by stress balance lifting method is 0.5 mm,which is just 10%of cut and cover method and 12%of coping method,respectively.The accumulated maximum floating of existing tunnel is 0.6 mm.It provides a new deformation control method for the overcrossing projects.
作者
白海卫
王剑晨
刘运亮
Bai Haiwei;Wang Jianchen;Liu Yunliang(Beijing Urban Engineering Design and Research Institute Co.Ltd.,Beijing 100037,P.R.China)
出处
《地下空间与工程学报》
CSCD
北大核心
2021年第5期1569-1577,共9页
Chinese Journal of Underground Space and Engineering
关键词
上穿施工
上浮变形
应力平衡顶推法
工法比选
overcrossing construction
floating deformation
stress balance lifting method
construction method comparison
