合肥轨道交通2号线怀宁路站暗挖通道施工技术研究

Study on the Construction Method of Subsurface Excavation Tunnel of Huaininglu Station of Hefei Subway Line 2

合肥轨道交通2号线怀宁路站1,4号出入口暗挖通道下穿长江西路,2个通道属浅埋~超浅埋,通道的上覆地层与围岩为人工填土和膨胀性黏土,工程环境条件复杂。采用合理的设计与综合施工技术,实现在合肥地区浅埋土质围岩且地面道路有车辆荷载的隧道暗挖施工。其要点包括:采用超前大管棚+超前小导管相结合的超前支护,4部CRD+预留核心土开挖工法并控制循环进尺,在暗挖通道穿越的地面主干道上满铺12000mm×2000mm×20mm钢板以减小隧道上部地表的车辆荷载。监控量测表明,拱顶下沉等数据均符合控制标准,地表沉降、管线沉降的发展过程与暗挖隧道拱顶下沉过程相似。

The subsurface channel No.1 and channel No.4 of Huai’ning road station of Hefei subway line 2 lies beneath the West Changjiang Road,the two channels are between shallow buried and super shallow buried in terms of buried depth.The environmental conditions are complex with artificial fill as overlying strata and expansive clay as surrounding rock.The reasonable design and comprehensive construction technology are adopted to realize the tunnel excavation in shallow buried soil surrounding rock and vehicle loading on the ground roads in Hefei area.The main points are as follows:the pre-support consisted of super pipe shed and anterior small catheter,CRD method and reserved core soil excavation method as well as controlling of cycled excavation footage,full 12000 mm×2000 mm×20 mm steel plates applied on the ground main road through the subsurface tunnel to reduce vehicle load on the upper surface of the tunnel.The monitoring measurements show that the data like the settlement of the vault both meet the control standard.The development of the surface subsidence and the pipeline settlement are similar to the vault settlement process of the tunnel.