Abstract: Based on the fact that Jiangmen Tunnel of Guangzhou-Zhuhai Railway under water-rich channel has characters of super-shallow, large cross-section and water-rich, this paper aims to propose a systematic analysis of the risks of the super-shallow tunnel with large cross-section under water-rich channel and to elaborate reasons for these risks and their potential detriments. After the initial comparison of possible pre-reinforcement means and excavation schemes, a quantitative comparison and selection is further conducted by using three-dimensional numerical simulation approach. It suggests that with the precondition of taking surface water-resisting measures, the excavation scheme in the combination of horizontal jet-grouting and large pipe roof advanced support and 3-bench method should be applied. As is suggested in the research, this scheme is not only effective to waterproof and reinforcing the stratum, but also has its advantages to eliminate the risks of collapse, accelerate the construction progress and reduce the cost at the same time on the prerequisite of ensuring the safety of tunnel construction, so as to provide some references for other similar projects.

Key words: super-shallow, large cross-section, water-rich channel, horizontal jet-grouting