The flow field and impact force on a debris dam

To study the mechanism involved in an impact process of debris flows we conduct flume tests with natural sand grains. A color coded particle tracking technique is used to measure the velocity field, phase velocity and the density distribution. Bi-directional load cells are used to measure pressure and stress at three different locations. To understand the effect of different mechanisms the constitutive law proposed by Julien and Lan is used in the momentum equation. The effect of gravity bottom stress, dynamic pressure and shock are all evaluated according to formula derived with experimental data. The total force calculated is very close to measured.