A Preliminary Design of Apparatus for Scour Resistance Test in Riverbed Sediments

Scour is a natural phenomenon caused by erosion or removal of riverbed or riverbank materials around bridge foundations by stream power. Under a given flood condition, the scour resistance of soil is one of the key factors that influence the scour process and the maximum scour depth. Scour does not occur when the flow velocity is lower than the critical scour velocity of the soil, or when the scour resistance in the soil is higher than the erosive load by streamflow. A preliminary design of apparatus to evaluate the scour behavior of soil sample is proposed in this study. The test can be carried out on soils samples both in laboratory and field conditions. A slender central blender near the soil surface is used to produce the erosive flow field. The rotation speed of the blade can be adjusted to reach the balance between flow structure and sediments. The plot of erosion rate and rotation speed provides the result of a scour resistance test. This device and testing method provide an easy way to measure the soil erosion resistance that can be used to predict the scour rate and depth around bridge foundation.