南昌市红谷隧道西岸基坑围护结构精细化设计

Fine Design of Foundation Pit Enclosure Structure of West Side of Nanchang Honggu Tunnel

南昌市红谷隧道为内河沉管隧道,江中段采用沉管法施工,两岸采用明挖法施工。介绍项目工程概况、特点和整体设计方案,综合考虑基坑深度、宽度、周边建筑、地下管线、市政交通等基坑设计条件。详细分析赣江高水位落差下的地下水位标高与其持续时间的变化特征,计算各水位工况时基坑围护结构的内力及位移,根据规范合理确定施工工况下各步骤的支撑布置。在基坑实际施工时,利用各代表水位工况时的基坑受力和变形分析,对应施工期间水位,合理确定基坑钢支撑的拆撑、换撑工序,为首节沉管段顺利沉放赢得时间,确保红谷隧道整体工期安排。

Nanchang Honggu tunnel is designed as an inland river immersed tunnel,among which the river mid-section is adopting immersed tube method and both sides are adopting open cut method.The project is introduced on its engineering survey,characteristics and the general design scheme with foundation pit design condition comprehensive thoughts of foundation pit depth,width,surrounding architectures,underground pipelines and municipal traffic,etc.And the paper analyzes the groundwater level under high water level drop and the changing features of the duration in Gan River;it calculates the internal force and displacement of the foundation pit enclosure structure at each water level;finally,according to the standard,the supporting arrangement of every step under the construction condition is reasonably determined.In the actual construction of the foundation pit,the foundation pit force and deformation analysis of representative water level condition are used to correspond to the construction period of water level,to determine reasonable disconnecting & changing support process of foundation pit steel support,which can save time to ensure the first tube section immersed successfully and to ensure the whole construction schedule arrangement of Honggu Tunnel.