Author(s): Yu Inami; Takeshi Fujiiinami; Hiroki Yabe; Takaaki Abe
Linked Author(s):
Keywords: Debris flow; Mud flow; Flume experiment; Disaster of structure; Alluvial fan
Abstract: Collapse of bridges caused by debris flow attracts much notice since it can make a supply route of logistics unserviceable and slows disaster recovery. In this paper, behaviors of debris flow and mud flow around a house, as well as conditions of their blockage and dam-up around a bridge are presented. Authors conducted a flume experiment for the purpose of clarifying the influence that a debris flow and mud flow gave a structure. The flume experiment had three parameters: slope, bed materials and discharge. In addition, a house or bridge model was installed in the flume and these were connected with force meter. After debris flow collided with house model, gravel included in the debris flow did not flow down, and only water included in the debris flow flowed down. On the other hand, the mud flow flowed down just as it was after a collision and continued giving a house model a momentum. As a result, it was revealed that impact force of mud flow was stronger than impact force of debris flow. From this phenomenon, it is guessed that not only the momentary impact force but also reaction time is important factor in thinking about disaster of structure. After debris flow collided with bridge model, the debris flow occluded because it could not pass under the bridge. Sedimentation occurred from the occluding point and it overflowed the bridge. Subsequently, the riverbed under the bridge was scoured locally. The occurrence of debris flow followed by riverbed change. On the other hand, in the case of the mud flow, occluded and overflowed like the debris flow. However, water included in the mud flow percolated through riverbed and the riverbed that was getting mud flow flowed down.
Year: 2018