低渗透膨胀性黏土层浅埋暗挖隧道超前支护方法研究

Advanced Support Method Study for Shallow-buried Excavation Tunnel in Expansive Clay Layer with Low Permeability

结合合肥地区膨胀性黏土层低渗透性的特点,对合肥地铁1号线暗挖试验段超前支护方法进行现场实验,将采用小导管超前注浆加固土体与不采用小导管超前注浆加固土体的方法进行了对比,通过有限元数值模拟计算及现场监测结果对比分析,合肥地区低渗透膨胀性黏土采用小导管超前加固土体注浆效果不明显,对于浅埋段及其他特殊性地段可采用管棚、超前锚杆等超前支护方法进行加固土体,效果良好。

Combined with the low permeability characteristics of expansive clay layer in Hefei, this paper carried out a field experiment of advanced support methods for Hefei Subway Line lexcavated section, the methods of reinforcing soil with or without adopting small duct pre-grouting were compared. Through the contrast analysis of finite element numerical simu- lation calculation and field monitoring results, it showed that the effect of reinforcing soil with small duct advanced grouting was not obvious for expansive clay with low permeability in Hefei, while adopting advanced support methods of pipe shed and advanced anchor bolt for reinforcing soil in shallow-buried section and other special sections, the effects were good.