软硬不均地层盾构机开仓换刀状态下开挖面稳定控制技术

Control Technology for Ensuring Shield Tunnel Face Stability Under Replacing Cutters with Opening Chamber in Hard-soft Heterogeneous Ground

在盾构机掘进过程中,如需在自稳性差的地层中开仓换刀,确保开挖面稳定是盾构安全施工的关键技术之一。本文针对软硬不均地层,从防止开挖面涌水、保持开挖面稳定、土仓加压试验等方面,研究确定了开仓换刀时的极限支护压力和气压值的方法,给出了合理的气压值;阐明了分级制作开挖面泥膜、维持开仓检查过程中的气压、管片背后注浆封水、切口环部位注浆封水等稳定开挖面的措施。采用土仓加压与增强开挖面稳定性相结合的技术,确保了盾构开仓换刀状态下开挖面的稳定,带压进仓作业顺利,工程效果好。

In the process of shield tunnelling,it is one of the key technologies to ensure the stability of the tunnel face in the case of opening the chamber to replace the cutters in poor self-stability ground conditions. In this paper,a method to determine the limit support pressure and pressure value while opening the chamber to replace the cutters in hard-soft heterogeneous ground was given and it was proved to be valid to ensure the stability of the tunnel face and prevent water flowing into the chamber through the tunnel face compression tests. Meanwhile,there were some engineering measures suggested to ensure the stability of the tunnel face,including making mud membrane step by step,maintaining the compressed air pressure during the process of opening the chamber to check the cutters,and grouting in the back of the segments and in the cutting ring to prevent water flowing into the tunnels. When the tunnel face is reinforced and exerted by compressed air simultaneously,its stability will be increased. Therefore,the operations to the cutters in the chamber are smoothly done in this project and a good engineering effect has been achieved.