Fluctuating uplift acting on rock blocks at the bottom of river bed and estimation of the limiting scour depth

Abstract

The hydrodynamic pressures and its propagation within rock cracks must be taken into account to study the development of scour pool due to jet impact downstream of high dams. In this paper, the transmission mechanism of fluctuating pressure in cracks of bedrocks is investigated by using the model of transient flow. A formula for calculating the maximum fluctuating uplift is deduced. The result is verified by the model test. Based on the analysis of forces acting on a rock block, a formula for estimating the limiting scour depth is established. And the formula is applied to the scour depth prediction at the well-known Three-Gorges Dam