Device for measuring excavation over-running which is installed on a shield-type tunnel excavator

摘要

Device for measuring excavation over-running by a tunnel excavator of the type having a shield 30 in which a cutter-holder 36 is made to rotate in a cutting chamber 33 defined in the front part of a shield body 31 of the excavator in such a way that the cutters of the said cutter-holder carry out the excavation of the working face of the tunnel as the said shield body advances with a view to forming a tunnel, the said device comprising a retractable probe which projects radially outside a part of the excavator and means 40 for detecting the projection length of the said probe in order to specifically measure the size of excavation over-running from a position in which the probe comes to bear against the working face of the tunnel, characterised by the fact that the probe comprises a probing rod 44 which is moved in a to-and-fro motion by a member 41 for actuating the probe and a pressure sensor 46 fixed to the end of the tip of the said probing rod, the said device furthermore comprising a detector 47 for detecting the travel of the probe by determining at least the projection length of the probing rod when the pressure sensor reaches the ground. <IMAGE>