Study on mechanism of capturing debris flow into wire net works

Abstract

Wire net works, which is expected to capture the debris flow efficiently by its large deformability, captured debris flow successfully on 18^th - July in 2004 at Matsumoto district and also at Tateyama in 2003. And these activities of capturing were recorded as movies. Design of these structures is based on a static analysis theory though the debris flow is evidently on dynamic behavior. We analyzed these movies in order to find the mechanism of the function that wire net works capture debris flow, and also to find the accurate design method by the comparison between expected values on design process with calculated ones on analyzing actual debris flows within deformation of flexible structures. We found the expected values on design such as debris heights and velocities were in case half of the analyzed one, and also found that debris flow pressure is more efficient to the deformation than sediment pressure, because of different characteristics between dynamic one and static one, and also because of flexible and structural function of nets. It should be enough to use only debris flow pressure for the designing wire net works on the knowledge of flexible structure deformation.