UNCONFINED SUBAQUEOUS DEBRIS FLOW

Provided by Gary Parker, St. Anthony Falls Hydraulic Laboratory, University of Minnesota.

Total Time: 1:30 (7.5 MB)

These experiments build a amalgamated debris flow deposit without interaction with tank walls. The tank size is 395 cm long x 213 cm wide x 57.2 cm deep. The slurry enters the tank down a duct at 9.2°, when it enters the tank the slope drops to 6.4°. Cameras are located at various positions over and inside the tank.

The mixture used in the flows shown consists of 30% water, 25% kaolinite clay and 45% silica (abbreviated on in the movie as 30w25k). Various flows were fed into the tank, only flows 2_2 and 2_4 are shown in this movie.

Flow 2_2 shows a flow coimng into the basin over a previous deposit. At the toe of the underlying deposit the new flow captures water below it and begins to hydroplane. The head of the flow accelerates and detaches from the body of the flow. A plug-like block skittles towards the camera.

The second flow shown (Unc2_4), shows loading and deformation of the water saturated underlying deposit. This produces what seems to be a wake as the debris moves down the deposit.

Starting around 47 seconds the flow gets diverted to the right, as its own deposits impede its motion.

At 1:09, the debris flow stops, but its secondary turbidity current keeps moving down the basin towards the camera.

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