高水头粉细砂层锚索施工技术研究

Research on Construction Technology of Anchor Cable in High Water Head Silt and Fine Sand Layer

北京地铁6号线新华大街站施工时基坑主体围护结构采用钻孔灌注桩,孔桩中部采用外拉锚索的支护形式,基坑标准段打设4道锚索。第3道锚索穿越高水头粉细砂层地质,部分锚索施做时出现涌水、涌砂,导致锚索不能施做。本项目经技术创新,采取套管与钻杆同步钻进、设计防涌砂装置、设置孔口吸水快速膨胀材料封堵等技术措施,有效防止了涌水涌砂问题,确保了锚索施工质量及工期。

During the construction of Xinhua Street Station of Beijing Metro Line 6,the main retaining structure of the foundation pit was constructed with bored piles,the middle part of the bored piles was supported by external anchor cables,and 4 anchor cables were laid in the standard section of the foundation pit.The third anchor cable passed through the high water head silty fine sand layer,and water and sand gushing appeared during the construction of some anchor cables,which made the anchor cable unable to be constructed.Through technological innovation,the project adopted technical measures such as synchronous drilling of casing and drill pipe,design of anti-sand inrush devices,and setting of water absorption and rapid expansion material plugging of orifices,which effectively prevented water and sand gushing,and ensures the construction quality and construction period of anchor cable.