UNDERGROUND STRUCTURE EVALUATION METHOD BASED ON ANALYSIS OF THREE DIMENSIONAL PARTICLE MOVEMENT OF DISCHARGE ELASTIC WAVE DURING DIGGING OF CHUTE

摘要

PURPOSE:To facilitate analysis of underground structure by detecting elastic wave which is discharged from drill bit by an AE sensor in a chute, determining the direction of digging bit via three dimensional analysis, and learning the existence of reflection surface based on difference of time between direct wave and reflected wave. CONSTITUTION:Blastic wave which is discharged from a drill bit 11 during digging is detected by an AE sensor 14 for three axis AE measurement which is provided in a monitoring chute 15 which is digged apart from a digging chute 12, and AE signal is sampled by a measuring car 16. Next, AE signal is filtered in the frequency range which is sufficiently lower than resonance frequency of the sensor 14, and the direction of the bit 11 is detected by the analysis of three dimensional particle movement. Reflection surface of elastic wave which exists in the direction of digging (boundary of ground layers) is evaluated based on the direction of relative progress and difference in reach time of direct wave and reflection wave. Consequently, it is possible to perform the analysis of underground structure easily at real time.