2017 Volume 70 Issue 3 Pages 25-32
Ohori et. al. (2013) mentioned Ground Penetrating Radar (GPR) applied to check dams was possible to detect weak region of strength of concrete. To clarify 3-D image of surface displacement and distribution of internal clacks in the dam, this article shows that application of SfM-MVS and GPR to a check dam (Sabo dam) with clacks by a debris flow which was occurred in Nagiso Chou, Nagano Prefecture at July 9, 2014. Because a catch dam is concrete structure, GPR is assumed to be a good investigation tool in order to earn 3-D mapping data of internal clacks. Another merits of GPR is portability and easy-to-use in fields. Our result shows the clacks are categorized as mainly three types : 1) a large clack which possibly cause a dam collapse, 2) complexity shape of clacks, and 3) a small size of clacks. Applicable range of our study is that 800 MHz GPR clearly traces continuous clacks inside a concrete dam at least less than 1.0 m depth.