A study on ultrasonic attenuation mechanism in crystalline rock core sample

2016 Fiscal Year Final Research Report

• Project/Area Number: 26420459
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: Okayama University
• Principal Investigator: Kimoto Kazushi 岡山大学, 環境生命科学研究科, 准教授 (30323827)
• Co-Investigator(Renkei-kenkyūsha): NISHIYAMA Satoshi 岡山大学, 環境生命科学研究科, 教授 (00324658)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 結晶質岩 / 超音波 / 表面波 / 散乱 / 減衰

Outline of Final Research Achievements

In this study, ultrasonic measurements and the signal processing were carried out aiming to understand the elastic wave propagation characteristics in a highly heterogeneous crystalline rock core samples. For the ultrasonic measurements, PZT and laser Doppler vibrometer were used. With the measurement setup, longitudinal (L), shear(S) and Rayleigh surface(R) waves transmitted through a cylindrical granite samples were measured. It was shown as the result, that the granite core behaves as an acoustically orthotropic material which can support a ballistic waves having the frequency components up to 500kHz. Another important finding is that the grain boundaries act as a relatively weak scatterer while strong scattering occurs at more sparsely distributed micro cracks.

Free Research Field

非破壊検査