MEASUREMENT OF STRESSES IN THE STEEL RIBS USED FOR NATM TUNNEL BY MAGNETIC SENSOR

Abstract

A magnetic sensor built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material was used to measure stresses on the surface of steel members in a nondestructive manner. This technique was applied in the tunnel fields to measure stresses of steel ribs, used as tunnel support structures, to confirm expected measurement accuracy. The results of stress measurements conducted on multiple occasions show that this method could be one of the promising technologies for non-destructive stress measurement for safety management during and after the construction of underground structures.