盾尾密封的完整性和可靠性对于盾构施工安全极其重要。当盾尾刷出现损坏时，要及时进行更换，而进行盾尾刷更换的关键在于地层中地下水的封堵。文章以南京纬三路过江通道N线工程为例，结合高水压强渗透地层盾尾刷更换施工的特点和要求，采用了改进的注浆止水技术。一是通过加强同步注浆，形成第一道止水体系；二是采用增设预留孔的两环特殊管片，对盾尾区域进行止水加固；三是在盾构B环注入聚氨酯形成止水带，防止前方泥水舱泥水后窜。通过采取多道措施形成一个厚度大、密实性高、且具有一定强度的完整止水体系，在无水的环境中成功更换了盾尾刷。%The integrity and reliability of shield-tail sealing are very important to the safety of shield tunnelling, and tail-seal brushes need to be replaced quickly in case of any damage; therefore the sealing of underground water is key to success in these cases. Taking line N of the Nanjing Weisan Road river-crossing project as an example, and considering the characteristics and requirements of replacing a tail-seal brush in a strong, permeable strata with high water pressure, an improved grouting technique was adopted for stopping water: 1) the primary water-stopping system was formed by strengthening the synchronous grouting; 2) the shield-tail part was consolidated by grouting via two special segments with additional reserved holes; and 3) the B-ring of the shield was grouted with polyurethane to avoid leakage from the front of the slurry chamber. Using this method, a complete water-sealing system characterized by its thickness, high density and strength is formed, ensuring successful replacement of the tail-seal brushes in a dry environent.
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