The Effect of Geotextile Layer in Decreasing Local Scour of Cylindrical Bridge Pier

Flood currents are considered threatening factors by creating local scour along bridge piers. One method for decreasing local scour is to strengthen the bed against imposed tensions. Among methods which can directly be appropriate in decreasing and controlling local scour of bridge piers is to employ geotextile around bridge piers. In the present study, the effect of geotextile layer in decreasing local scour of cylindrical single-pier was investigated with the purpose of proposing the best effective method of covering bridge pier. So, layers with circular and oval shapes were put around the pier, in proportion with pier diameter, and the performance of each was compared with the unprotected pier. Test results showed that with installing the oval geotextile layer, final scour depth around the pier reached to 1.25D. Also, comparing geotextile and collar with 2D diameter, the delay of scour process around geotextile was 40 times higher than the collar, but the collar decreased the ultimate scour depth further than geotextile.