[H-TT15] Non-destructive techniques applied to stone cultural heritage

[HTT15-P01] Ultrasonic velocity attempted to the various rocks - laboratory experiment and field measurement -

*Chiaki T. Oguchi¹, Keishin Takahashi², Sota Noshiro², Yukina Ikeda¹ (1.Institute for Environmental Science and Technology, Graduate School of Science and Engineering, Saitama University, 2.Faculty of civil Engineering, Saitama University)

Keywords:Ultrasonic velocity , Tuff, Taya Cave, Porosity

The ultrasonic velocity test is one of the non-destructive and easy handling devices that allows the physical and mechanical properties of rocks to be investigated. Despite many research reports, there are still unclear in applying performed in the laboratory and the field as well. In this study, the correlation among porosity, hardness and the ultrasonic velocity was investigated by using soft rocks. First, for various tuffs (Oya tuff, Ashino tuff, Towada tuff, and Tatsuno tuff), the ultrasonic velocity of the rock sample in the air-dried state and the wet state was measured in the laboratory. As a result, the speed in the wet state was higher than the speed in the air-dried state in all cases except Towada tuff. On-site measurements were also performed at the Taya Cave (Sakae-Ku, Yokohama). The Taya Cave is composed of early to mid-Pleistocene deposits and is extremely low in strength. In the field, measurements were taken by the surface method at intervals of 20 cm. Although the sensitivity was low, the measured values converged and reproducible values were obtained.