Debris flows are geohazards consisting of an irreversible deformation of sediment-water mixtures. They have a high destructive potentiality and, therefore, geotechnical engineers have to find effective countermeasures to reduce the risk. The understanding of their behaviour is fundamental to be able to predict the flow and find the best solutions. However, relevant data are difficult to be obtained from natural debris flows: physical modelling is an effective tool to study these mass movements in detail. Laboratory tests are performed within this thesis. The following issues are analysed:- Influence of release volume and sediment concentration on the flow behaviour.- Representativeness of small-scale experiments compared to natural debris flows.- Numerical simulation of some tests and influence of sediment concentration on the rheological parameters.Several debris flows are tested on a 5 m long runout channel, sloped 17°, and a 4 m long deposition zone, sloped 2°, aiming at representing 1/20 scale.