浅埋大断面矩形顶管下穿京杭大运河施工关键技术研究

Construction Technique Study on Shallow-buried Large-section Rectangular Pipe Jacking Undercrossing Beijing-Hangzhou Grand Canal

针对超浅埋大断面矩形顶管穿越河流的工程案例研究较少,尤其是较少涉及施工问题方面的研究。结合浅埋大断面矩形顶管下穿京杭大运河工程,对矩形顶管施工方案和顶管机选型进行优化,解决了施工期间始发井洞前加固区外地面沉降、管节对接时止水条损坏及刀盘卡嵌等工程问题,并给出了解决方案,确保了工程的顺利完工。结合现场实测数据,对矩形顶管顶进过程中的施工效率、顶力和摩阻力大小以及刀具磨损等进行研究,得出顶进速率较慢时,顶进摩阻力显著增大,通过减阻泥浆减阻能够有效降低其侧摩阻力。下半部的刀盘相较于上半部刀盘磨损情况更为严重,多数刀盘出现合金块磨损严重、崩开及脱落现象。

There are relatively few engineering case studies on super-shallow buried large-section rectangular pipe jacking crossing rivers,and the research on construction problems is particularly less.Based on the project of shallow-buried large-section rectangular pipe jacking underpassing the Beijing-Hangzhou Grand Canal,both the construction scheme of rectangular pipe jacking and the selection of pipe jacking machine are optimized,which solves the engineering problems such as outer ground subsidence of the front reinforcement area of the starting shaft during the construction period,water bar damage during pipe joint docking and cutterhead embedment,and provides solutions to ensure the smooth completion of the project.Combined with the field measured data,the construction efficiency,jacking force,friction resistance and tool wear in the jacking process of rectangular pipe jacking are studied.It is concluded that when the jacking rate is slow,the jacking friction resistance increases significantly,and the side friction resistance can be effectively reduced by reducing the friction reduction mud.The wear of the lower half of the cutterhead is more serious than that of the upper half of the cutterhead.Most of the cutterheads have serious wear,collapse and shedding of alloy blocks.