SCOUR AROUND DIFFERENT SHAPES OF PIERS AT DIFFERENT ORIENTATION WITH FLOW

Abstract

Scour is the process of local lowering of stream bed elevation which takes place in the vicinity or around a structure constructed in flowing water. Scour takes place around bridge piers, abutments, around spurs, jetties and breakwaters due to modification of flow pattern in such a way as to cause increase in local shear stress. Due to improper knowledge of scour around bridge pier, there were lots of bridges failure cases faces by our country which leads to economic loss and life loss. To understand the phenomenon of local scour around piers an attempt is done by experiment on different shape of bridge piers at different angle of attack of flow. A series of experiments were performed to study the phenomenon of local scour that takes place beside a bridge pier of different shape on straight channel at different angle of attack, and to investigate the relation between the dimensions of the scour hole and between non-dimensional parameters describing the flow ratio, and angle of flow attack. All tests were held under clear-water condition, using a horizontal bed consisted of non-uniform sandy soil. The experiments were conducted under different condition of flow parameters which helps to better understanding of local scour around different shapes of piers, and piers along the channel flow, across the channel flow and inclined to channel flow. The shape of scour hole, depth of scour, length of scour hole upstream and length of scour hole downstream helps in understanding geometry of scour hole and rate of scour in different cases of piers shape and orientation. Under the different condition of flow, its helps to understanding the scour depth variation with time, with parts run of flow and with continuous flow run in a certain time. The others parameters like length of scour hole upstream and downstream to study the variation of geometry of scour hole. With the different shape of piers, the pier having minimum scour is best for the design consideration for scour point of view, it also helps in designing of foundation as the increasing depth of foundation increase the cost of project with proper knowledge about scour phenomenon helps in designing cost effective piers.