鉱山における支保鋼材のAEに関する研究

Abstract

Experiments were made to estimate the loads acting on the steel arch support by means of the acoustic emission (AE) technique. By the bending test of the I-steel for arch support, the following results were obtained:1) The impulsive AE signals of the I-steel began to generate from the level of half of its yielding stress and the AE activity became at a high degree during the process of its yielding. The AE activity of the I-steel formed into an arch at an ordinary temperature was very low. But the laggings on the steel arch displayed the high AE activity under a low load by the friction between laggings and steel or their collapse.2) In the bending test, it was able to estimate the stress history of I-steel by Kaiser's effect and to locate the sources of acoustic emissions. But it was difficult to estimate the stress history of the I-steel used in mine arch supports, because its AE activity was degenerated due to the bending in the formation of an arch and the noises of the dispersal of rusts from the surface of the specimen were generated.3) The yielding stress of the I-steel formed into an arch at an ordinary temperature decreased to nearly half of that of the original straight I-steel due to Bauschinger's effect.4) By normalization the formed I-steel recovered nearly 90% of the original yielding stress and the AE activity slightly.It will be able to estimate the direction of the load acting on the steel arch by the source location of AE generated between laggings and steel arch. And the I-steel formed into an arch at an ordinary temperature should be normalized.