CHARACTERISTICS OF SCOUR AROUND REPELLING SPUR-DIKES

摘要

Analysis of scouring process around repelling (60? submerged spur-dikes are presented based on experiments under movable bed scour. Study objectives included highlights on the movement of bed materials and local scour around spur-dikes at constant bed shear stress with uniform flow condition. The effects on scour depth of spur-dike length (b); spur-dike height (d) and flow depth (h) have been investigated with the help of experimental data. Final state of scour holes and deposit locations along the longitudinal direction are discussed herein. The longitudinal bed and water surface profiles are presented to find out the effect of bed degradation on the water surface level. Comparison between repelling and deflecting (90? spur-dikes has also been discussed from the local scour point of view. It was found that the scour process around repelling and deflecting spur-dikes had little difference only in the shape of scour area, which depends on the inclination angle of the spur-dike in the flow direction. Both local scour and maximum scour depth observed at final state have found to be affected by the height (d) and the length (b) of the spur-dike. In case of small spur-dike length (b), local scour area was limited and no bank erosion can occur in downstream area. The data collected for both repelling and deflecting spur-dikes will be useful for the development of numerical models of scour around submerged spur-dikes.