Flow-altering countermeasures against scour at bridge piers: a review

Abstract

During the past decades, several investigations were conducted to assess the adequacy of countermeasures against local scour at bridge piers. The countermeasures can be broadly classified into two categories: (1) flow-altering and (2) bed-armouring countermeasures. Flow-altering countermeasures, as treated herein, can be classified into four main groups based on their shapes and performances. A comprehensive review of the up-to-date studies on various types of flow-altering countermeasures is presented, placing special emphasis on recently proposed methods while also revisiting studies of former methods. Experimental conditions of different studies under which the tests were performed are critically examined. A preliminary evaluation of the previously conducted experiments indicates that the results of several tests were influenced by side-wall, sediment size, flow shallowness and temporal effects. Experimental results on the combinations of different countermeasures, including their limitations and difficulties in field applications, are also discussed. Finally, suggestions are presented for further research on selected countermeasures.