MATERIAL AND METHOD FOR LUBRICATING THE METAL SURFACES OF AN EARTH-PRESSURE TUNNEL BORING MACHINE

摘要

A method of boring a tunnel with a tunnel boring machine comprising injecting into the formation to be bored just before the cutting tools of the boring machine and optionally into the internal discharge chamber of the boring machine, an aqueous foam containing at least one clay, at least one surfactant and at least one gas in proportion to produce a good quality, stable foam with the formation material and discharging the material from the tunnel via the discharge of the boring machine.