粉细砂层中锚索施工涌水涌砂的处理技术

Treatment of water and sand kicks in silty fine sand in anchor cable construction

摘要:

广州市良业大厦基坑支护工程存在较厚的淤泥质粉细砂层，预应力锚索锚点位置处于粉细砂层中时，锚索施工易发生涌水涌砂现象而引发基坑事故。施工过程中通过采取跟管钻进干钻成孔、墙后孔口设置止浆袋及墙后注浆的处理措施，减少了锚索施工过程中涌水涌砂现象的发生，避免了因涌水涌砂水土流失造成基坑外地面下沉而引发的基坑事故。

Abstract:

A thick layer of silty fine sand is present at the Liangye Tower foundation pit in Guangzhou, and when the anchor point of the prestressed anchor cable is in the fine sand layer, water and sand kicks are prone to happen in the construction of the anchor cable, leading to the foundation pit incidents. The drilling with casing process was combined with dry-drilling to make the borehole, and behind the wall both the grout stopping bag was set at the borehole head and grouting was performed to ensure reduction in water and sand kicks during anchor cable construction; thus avoiding the foundation pit incident caused by the external ground subsidence.