地铁超大断面区间近距离穿越复杂环境施工技术研究

Study on the Construction Technology of Metro Section Crossing Complex Environment in Short Distance

北京地铁19号线新~草区间渡线段结构断面大,近距离上跨既有10号线盾构区间和下穿市政道路管线。为有效控制既有线结构变形和街道地表沉降风险,采用了PBA法微拱直墙大断面结构,利用钢管桩柱构造超大断面形式,通过运用FLAC3D进行施工过程模拟,预测周边环境变形风险,制定多重支护抗变形措施。施工中采取管棚、管幕、分段分层开挖均衡减载、大直径钢管桩柱顶纵梁、底板低压注浆等关键技术,解决了复杂环境风险下地铁渡线段大断面区间施工难题,使得既有线结构上浮最大1.02 mm,道路沉降最大-38.6 mm,施工过程中风险始终安全可控。本工程的成功应用为地铁区间超大断面工程穿越变形要求严格的风险源积累了宝贵经验。

The cross section of the Xin-Cao section of Beijing Subway Line 19 is large,and there are shield-driven sections of Line 10 and municipal pipelines under it.In order to effectively control the deformation of existing line structure and the risk of street surface settlement,the large section structure of micro-arch vertical wall with PBA method,the super section form of steel pipe pile and FLAC3D were adopted to simulate the construction process,the deformation risk of the surrounding environment was predicted and the anti-deformation measures of multi-support were worked out.During the construction,key technologies such as pipe roof,pipe curtain,sectional and layered excavation,balanced load reduction,riding over large diameter steel pipe piles,and low pressure grouting of floor slab were adopted to solve the construction problems of large cross section of metro crossing line under complicated environmental risks,it could make the existing line structure rise up to a maximum of 1.02 mm,the road settlement to a maximum of-38.6 mm,and the risk was always safe and controllable in the construction process.The successful application of this project has accumulated valuable experience for metro section super-large cross-section project crossing the risk source with strict deformation requirements.