Article révisé par les pairs
Résumé : | Muons, cosmic rays produced continuously in the upper atmosphere penetrate the ground. Their flow at a given point depends on both the length of the path traveled and the density of the terrain encountered. Mounted in the structure of a tunnel boring machine as a telescope aiming at a given direction, a trio of muon detector measures and locates the variations of density and the possible voids. The use of such a system allows risk detection ahead of tunneling machines, as shown by the examples on 9.7 km of three sections of the new Paris metro, says the Grand Paris Express. |