Abstract: As a common measure of preventing debris flows, window-frame dam has functions of intercepting sediment and protecting riverbed and slopes. Through indoor simulation, the characteristics of debris flows passing through window dam was researched by controlling different variables. Results reveal that the variation of particle composition of debris flows before and after passing through the dam is largely correlated with the density of debris flow. When the density of debris flow is 1 650 kg/m³, the window dam’s sediment interception capacity is the largest. The density of debris flow decreases remarkably after passing through the window dam, and the decrease is affected by the type of window dam blocking; the regularity of decrease is similar despite different blocking types; when the density is around 1 800 kg/m³, its decrease is the largest. By regression analysis the relation between sediment interception ratio L and debris flow density γ_c was also obtained.

Key words: debris flow, simulation test, particle composition, rate of density decrease, sediment interception ratio