ABSTRACT
A 2m-ID microtunneling machine has completed this unprecedented performance. The machine developed was adapted to the specific constraints of the Livry-Gargan project (Paris area) with the addition of a backup tube hydraulically articulated and driven from the surface. The microtunneling machine is unique in its short length, which allows for its recovery from shafts with a smaller dimension but also to fit into curves of a very tight radius. The reinforced concrete jacking pipes used on the Livry-Gargan project were also subject to a specific curvature. The length of the pipes is reduced to 1.5 m with ends designed to ensure the watertightness of the pipe connections in the curve. Furthermore, the thrust is efficiently distributed over the section of the pipe by the installation of a hydraulic joint interposed in between the pipes (JackControl process).
