毗临地铁深大基坑内支撑拆除施工技术

Construction Technology for Demolition of Supports in Deep and Large Foundation Pit Adjacent to the Subway

深大基坑内支撑拆除工艺复杂,工期较长,且对安全性要求极高。中国农业科技国际交流中心项目基坑深度为25.5 m,采用"单排桩+3道钢筋混凝土内支撑+1道预应力锚索"的支护形式,该项目体量大,毗邻地铁站且周边环境复杂。经过方案比选,最终选用"绳锯切割+风稿"的机械拆除法进行施工。现场施工及监测表明,在满足拆撑的前提下,对内支撑进行分层分阶段拆除,基坑、楼板及周边环境的变形均在允许范围内,安全性高,且满足主体结构的进度要求。

The support removal process in the deep and large foundation pit is complicated,the construction period is long,and the safety requirements are extremely high.The depth of the foundation pit of the China Agricultural Science and Technology International Exchange Center project is 25.5 meters.It adopts the support form of"single row of piles+3 reinforced concrete internal supports+1 prestressed anchor cable".The project is large in volume,adjacent to the subway station and the surrounding environment is complicated.After comparing and selecting schemes in this article,the mechanical demolition method of"wire saw cutting+wind draft"is finally used for construction.On-site construction and monitoring showed that,under the premise of satisfying the dismantling of support,the internal support was demolished in stages,and the deformation of the foundation pit,floor slab and surrounding environment were all within the allowable range,with high safety and meeting the schedule requirements of the main structure.