Author(s)

R. Kaitna, D. Rickenmann & S. Schneiderbauer

Abstract

Debris flows present a serious hazard in mountainous regions. Though considerable research has been carried out to explain the movement of such heterogeneous mixtures of sediment, water, and air on a physical basis, rheologic models are still useful tools in engineering application. In order to study the flow behaviour of debris flow-like material, a vertically rotating flume as well as a conveyor belt-flume have been built. Both facilities allow to establish quasi-stationary conditions for an extended time period and to measure relevant flow parameters. Different mixtures of the synthetic polymer Carbopol Ultrez10 have been tested in the rotating flume as well as in the conveyor belt apparatus. Rheologic parameters of the Bingham model have been determined from drum data and from conveyor belt data for all mixtures following three different approaches. Independent measurements carried out in a conventional co-axial cylinder rheometer (Bohlin Visco 88) shows good agreement with the indirect determination of the rheologic parameters using the two experimental devices. Keywords: Bingham model, rotating drum, conveyor belt flume, Carbopol. 1 Introduction Debris flows are inherently complex and rare phenomena in mountain regions. Peak discharge and flow depth can be higher by an order of magnitude compared to flood events resulting from similar meteorological and hydrological conditions in the same catchment. High velocities and bulk densities ranging from 1.4 to 2.6 t/m³ [1], [2] are the reason of the very destructive nature of such mass flows. Depending on water content and the composition of sediments, various forms of flows have been observed [3]. Strong efforts have been made to explain the

Keywords

Bingham model, rotating drum, conveyor belt flume, Carbopol.