Tunnel Boring Machines (TBMs) are known that comprise a large metal cylindrical shield fronted by a rotating cutting wheel and containing a chamber where the excavated soil is deposited (and optionally mixed with slurry for extraction, depending on the type of geological/soil conditions). However, TBMs have various disadvantages including the stop-start nature of their tunnelling, and that a single TBM cannot easily transition between different rock/soil types (especially heavily fractured and sheared rock layers). The invention provides a tunnelling shield provided with jet grouting tools arranged to project from a leading edge thereof. In this way, the quality of the geological material into which the tunnel is being excavated may be improved dynamically as part of the excavation process.

A barrier forming apparatus for forming a barrier between an exposed tunnel face (107) and a tunnel boring machine (100), the barrier being formed by the application to the tunnel face of a barrier mixture comprising two highly reactive first and second components. The barrier forming apparatus (10) includes a first reservoir (11) for storing the first component, a second reservoir (12) for storing the second component, and a plurality of applicators (13, 14 and 15). The barrier forming apparatus (10) also includes a third reservoir (56) that is used to store a clearing fluid and a piston flow divider (58) having an inlet (59) and three chambers having respective outlets, (61, 62 and 63) that are in fluid communication with a respective applicator (13, 14 and 15). The applicators are maintained in a state of readiness by a regular supply of clearing fluid passing there through.

The present invention relates to a mechanical tunneling apparatus and process for a tunnel in a quicksand stratum. The mechanical tunneling apparatus comprises isolating apparatuses arranged at an upper end and a lower end of a supporting apparatus; an excavation apparatus arranged at a front end of the supporting apparatus; a spraying apparatus arranged on the isolating apparatuses and the excavation apparatus; a muck discharging apparatus arranged at a lower part of the supporting apparatus; and a propulsion apparatus arranged at a rear end of the supporting apparatus.