既有交通线路贯穿基坑的设计技术研究

为既有地铁隧道、市政道路所贯穿的基坑工程是设计行业亟待解决的工程难题,依托广州市珠江新城地下空间金穗路北区建设项目基坑工程,总结了几点设计关键技术:(1) 下穿基坑的地铁隧道采用密排挖孔桩+密肋梁的门式框架结构约束隧道变形,结合时空效应合理安排施工顺序,保证隧道在基坑施工期间正常运营;(2) 下穿基坑的地铁隧道与基坑边线交接部处理应灵活使用各种支护形式;(3) 市政道路横跨基坑时,基坑采用内支撑支护体系,内支撑下方土体正常开挖,同时在内支撑上覆钢便桥保证道路正常通行,并利用钢便桥作为管线原位保护的悬吊结构;(4) 综合运用岩土、结构、隧道、道路等专业知识,采用灵活的支护形式,实现基坑施工期间交通线路正常运行。

Study on Design Technology of Existing Traffic Line throughout Foundation Pit

The foundation pit engineering building on the existing subway tunnel and building under the municipal road is a difficult problem to be solved. Based on the Jinsui Road North District Project of Zhujiang New Town in Guangzhou, several technologies are summarized. (1) The foundation pit building on the existing subway, gate-shape frame of digging pile and waffle beam is used to avoid transformation of the subway tunnel. The construction order is arranged reasonably, so the tunnel can be operated normally during the period of construction. (2) Various kinds of support form are flexibly used in the joint points between the foundation pit and the subway tunnel which is under it. (3) If the foundation pit is under the municipal road, the inner support system is used, and digging can be proceeded under inner support. At the same time, a temporary steel bridge upper the inner support is for road normally operating and pipeline protection. (4) To achieve the traffic lines can be operated normally during the period of construction, professional knowledge, such as geotechnical, structure, tunnel, road, etc. should be synthetically used in foundation pit design, and flexible support form to be adopted.