Experimental Study on Impact Load on a Dam Due to Debris Flow

Abstract

We have measured the imdact load on a dam when debris flow clash into it and simultaneously observed the behavior of head part of the flow in experiments, that have been performed with glass beads of 5mm in diameter, in an open channel of 7m in length and 150mm in width.
When the velocity or debris flow is relatively low, the measured load can be explained as static load due to sediment of debris. When the velocity is relatively high, the measured load is greater than one of dynamic pressure of steady jet flow in same profile. In the case of latter, the measured load agree at each time with the load caused by the flow's momentum variation assessed from the observation. Then, a model has been proposed to evaluate the deformation of the flow and, in the result, load on the dam. In this model, the initial conditions (flow depth, bulk density) are expressed in functional relationships determined from the experiments, and the load can be estimated quantitatively. The profile of flow, the load on the dam, and their variation with time calculated by this model have proven to agree well with those observed or measured in experiments.