A Smoothed Particle Hydrodynamics Study of an Experimental Debris Flow

A comparison between a physical model debris flow of a monodispersed sand and a numerical model is presented. The physical experiment consisted of the instantaneous release of a saturated sand mass via a lock gate in a 220 x 160 mm rectangular channel of length 1.75 m. The sand mass had a 20 % moisture content and was placed in the same position behind the lock gate before each experimental run. Additional water was added to the mass to keep the sand particles in suspension. The inclination of the flume was 31 degrees which meant that the sand reached runout velocities of 1 m/s, approximately. The free surface of the flow was monitored in order to compare the readings to a Smoothed Particle Hydrodynamics (SPH) numerical model where a frictional Mohr-Coulomb model was implemented. This model was that of Voellmy, including the turbulent Voellmy coefficient. The free surface of the experimental flow was predicted well by the numerical model, showing the ability of the SPH model to predict the run out behaviour of small scale debris flow experiments with physically viable rheological parameters. This validation of the model is essential for its use in predicting landslide behaviour in the field. The prediction of the behaviour of landslides in areas that are susceptible to them is a key step in reducing the damage that they cause.