富水圆砾地层盾构隧道端头加固优化设计研究

Research on the Reinforcement Optimization of the Shield Tunnel End in Water-rich Pebble Stratum

南宁轨道交通3号线富水圆砾地层中盾构始发或到达时易发生流砂、涌水事故。基于此,文章通过理论计算、数值模拟对不同隧顶埋深、横向加固厚度、竖向加固厚度及纵向加固长度下端头土体的稳定性进行了分析,对止水加固厚度进行了优化设计,得到了经济、安全的富水圆砾地层盾构隧道端头加固范围,同时结合南宁地区施工经验,提出了采用混凝土连续墙+袖阀管注浆+井点降水的富水圆砾地层端头加固方案。实际工程应用效果表明,该方案对于富水圆砾地层是适用的。

As for the Nanning rail transit line 3 project in water-rich pebble stratum,sand gushing and water inrush accidents are prone to occur when shield launching or arriving.In this context,the paper analyzes the stability of the end soils under different buried depths,transverse reinforcement thicknesses,vertical reinforcement thicknesses and longitudinal reinforcement lengths through theoretical calculations and numerical simulations.On this basis,the thickness of water-stop reinforcement is optimized,an economical and safe reinforcement range of the shield tunnel end is determined.Combined with local construction experience and characteristics,the end reinforcement scheme including concrete diaphragm wall+sleeve valve tube grouting+well point dewatering is proposed for the studied project.The actual engineering application effect shows that the proposed scheme is applicable to the water-rich pebble formation.