Laboratory studies of subaqueous debris flows by measurements of pore-fluid pressure and total stress

A set of laboratory experiments on subaqueous debris flows is reported where total stress as well as pore pressure transducers were mounted in the bed. Sediment texture ranging from clayey (viscoplastic) to sandy (granular) were used in the experiments, in order to investigate changes in pressure evolution. The pressure readings confirm earlier studies suggesting that the front of the subaqueous clayey debris flow is hydroplaning on a thin layer of water, which causes low bed friction. Fronts of sandy debris flows show a fluidized head where bed friction is minimal.