Experimental Study of Debris Flows

A steady uniform flow of high concentration sand‐water mixture was recirculated in a flume using a progressing cavity pump. The flume was set on a slope of 28.6%. A specially designed volumetric flow sampler was used to measure the vertical velocity and concentration profiles at the center of the channel. Velocity and concentration distributions are presented for flows with almost uniform sand particles of sizes 0.430, 0.335, and 0.215 mm. Similar distributions are also presented for flows having a mixture of these three sand sizes with a mean diameter of 0.33 mm. Mean volumetric concentrations for these flows ranged from approximately 2.5% to 43.5%. These measurements are compared with the predictions of dilatant fluid as well as laminar and turbulent Newtonian fluid models. The difficulties associated with laboratory handling and measurements of high concentration fluid flow in an open channel have been discussed.