ABSTRACT
A spur-dike is one of the measures used for protecting river banks against erosion. This structure deflects streamlines from river banks and leads them to the river center line. Rubble mound spur-dikes mainly designed for unsubmerged conditions but due to the flood conditions, submergence of this structure occurs thereby instabilities which needs to be studied. In this paper, the results of experiments on the effect of grain size on the progressive failure mechanism of a rubble mound spur-dike are introduced. For this purpose, nine experiments were carried out with three average diameters for grain size and three different flow velocities. Flow depth and spur-dike geometric parameters are kept constant and flume bed being rigid in this research. Experiments were conducted in a laboratory flume 6 m long, 0.45 m wide and 0.45 m deep. To understand the progressive failure of a rubble mound spur-dike, incipient motion of grains and mechanism of failure were recorded with camera in and relationship between the average grain diameter and the flow velocity, along with the mechanism of failure of a submerged rubble mound spur-dike are discussed.
