Solid-fluid-gas coupling prediction of harmful gas eruption in shield tunneling

- Solid-fluid-gas three-phase coupling in FLAC3D was implemented by the Fish language.
- A good prediction of harmful gas eruption was done by the numerical modeling.
- Some safety standards for the tunneling in the harmful gas strata were put forward.
- An automatic monitoring system was designed for the shield tunneling construction.

In some cities in the south of China, a stratum of explosive gas was often be encountered in shield tunneling, as well as in other countries. However there is no function of explosion-proof function in the shield machine, and it is likely to cause a large number of harmful gases gushing out instantaneously. The harmful gas concentration can exceed the safety alarm value and even lead to explosion. Based on the above issues, solid-fluid-gas three-phase coupling is analyzed with relevant theories and assumptions through FISH language programming in FLAC3D, which originally only has the solid-fluid two-phase coupling function. The prediction of harmful gas eruptions in shield construction is realized. On this basis, a set of real-time monitoring systems for the harmful gases is constructed, which realizes staff evacuation warnings. The research achievement has been successfully applied in a practical project.