| Ohori et. al. (2013) mentioned Ground Penetrating Radar (GPR) applied to check dams was possible to detect weak region of strength of concrete. To clarify3‐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 earn3‐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 that800MHz GPR clearly traces continuous clacks inside a concrete dam at least less than1.0m depth. |
