Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

Symbol S (Solid Earth Sciences) » S-TT Technology & Techniques

[S-TT13] Recent Advances in Exploration Geophysics (RAEG2015)

Thu. May 28, 2015 11:00 AM - 12:45 PM 102A (1F)

Convener:*Hitoshi Mikada(Kyoto University), Junichi Takekawa(Graduate School of Science, Kyoto University), Junzo Kasahara(University of Shizuoka, Faculty of Earth Scieces), Yoshihisa Iio(Disater Prevention Research Institute, Kyoto University), Yasuo Ogawa(Volcanic Fluid Research Center Tokyo Institute of Technology), Nobukazu Seama(Department of Earth and Planetary Sciences, Graduate School of Science, Kobe University), Tatsuya Sato(Geothermal Energy Research & Development Co., LTD.), Eiichi Asakawa(JGI, Incorporated), Chair:Toshinori Kimura(Japan Agency for Marine-Earth Science and Technology), Kyosuke Okamoto(Railway Technical Research Institute)

11:15 AM - 11:30 AM

[STT13-08] Improvement of eddy current testing method for sheet piles on harbor

*Takuya SAITO1, Hitoshi MIKADA1, Junichi TAKEKAWA1 (1.Graduate School of Engineering, Kyoto University)

Keywords:NDT, Eddy current testing method, Fictitious wave domain method, Migration, Attribute analysis, Electromagnetic

The applicability and the feasibility of eddy-current testing method for the detection of wall thinning and surface crack of steel structure have been practically confirmed by field and laboratory experiments. Qualitative analysis of cracks has been empirically understood by analog analysis. There has, however, been a growing demand to quantitatively evaluate the cracks. We tackle this problem by use of time series of induced magnetic field by the cracks.
In the present study, we proposed a new digital analysis process to use the induced magnetic field waveform, and validated the effectiveness of the method using numerical simulations. First, we developed a high-speed electromagnetic simulator using a fictitious wave domain method to reproduce the conventional eddy current testing method for realistic sheet-piles seawater model. Then, we confirmed the features of the induced magnetic field waveforms by many types of cracks.
Paying attention to the residuals of the induced magnetic field waveform, we developed a novel migration procedure that has not been used up to now in electromagnetic field. Using this, we could get crack imaging without phase lag. For the evaluation of the crack position and wall thinning of the sheet piles, we also applied attribute analysis used in the field of seismic survey.
Through the application of the digital signal processing using induced magnetic field waveform, we could be successful with developing a high degree of accuracy of the eddy current testing method.