Debris flow stops and deposits when it reaches an alluvial fan. There are often many houses on the fan, and they seem to influence the debris flow flooding and deposition process. In this study, we conducted model experiments and numerical simulations with a debris flow simulator Kanako2D, in order to confirm the influence of houses. The model experiments results show that when there are houses, debris flow spreads widely in the cross direction just upstream of the houses, especially when the flow discharge is large or the grain size is small. The houses influence is shown in the simulation, too. We also considered houses destruction in the simulation with simplified method using fluid force. When some houses are destroyed by debris flow, the deposition conditions change from that when the houses are not destroyed. Debris flow grain size and peak discharge have an effect on houses destruction.

Key wordsFdebris flow, alluvial fan, house, model experiment, numerical simulation