深厚软土地区城市立交隧道设计

Design of Urban Interchange Tunnel in Deep Soft Soil Area

针对深厚软土地区城市立交隧道设计关键技术方案研究,以广州市南沙区珠江大道隧道为背景,结合工程建设条件开展了隧道结构、隧道基础、基坑支护等设计方案分析和论证。分析结果表明:城市隧道推荐开口段U形槽结构侧墙和底板均采用矩形截面进行设计,闭口段采用矩形框架结构进行设计,能够最大程度地压缩基坑开挖宽度,为临时通行便道预留足够的通行宽度;在深厚软土地区隧道基础设计推荐采用预应力管桩,管桩与隧道底板连接方式可采用刚性连接或托板支撑连接,针对有抗浮要求和跨越沉降控制严格的结构物处,采用灌注桩;基坑围护形式的选择应根据基坑开挖深度、地质情况、场地条件、环境条件以及施工条件等,通过多方案比选确定,最终形成安全可靠、技术可行、施工方便、经济合理的多种支护结构型式组合方案。

Aiming at the research on the key technical scheme of urban interchange tunnel design in deep soft soil area,taking the Pearl River Avenue Tunnel in Nansha District of Guangzhou as the background,combined with the engineering construction conditions,the design schemes of tunnel structure,tunnel foundation and foundation pit support are analyzed and demonstrated.The analysis results show that:The side wall and bottom plate of the U-shaped groove structure in the recommended opening section of the urban tunnel are designed with rectangular cross section,and the closed section is designed with rectangular frame structure,which can compress the excavation width of the foundation pit to the greatest extent and reserve enough passage width for the temporary passage.Prestressed pipe piles are recommended for tunnel foundation design in deep soft soil areas.The connection between pipe piles and tunnel floor can be rigidly connected or supported by pallets.For structures with anti-floating requirements and strict control of cross-settlement,cast-in-place piles are used.The selection of foundation pit support form should be based on the excavation depth,geological conditions,site conditions,environmental conditions and construction conditions of the foundation pit.Through the comparison and selection of multiple schemes,a combination scheme of multiple support structure types with safe,reliable,technically feasible,convenient construction and economical and reasonable is finally formed.