LOCAL SCOUR AROUND BRIDGE PIER

LOCAL SCOUR AROUND BRIDGE PIER

INTRODUCTION:

Scour is a natural phenomenon caused due to the erosiveaction of flowing stream on alluvial beds which removes the sediment around ornear structures located in flowing water. It means the lowering of the riverbedlevel by water erosions such that there is a tendency to expose the foundationsof a structure. It is the result of the erosive action of flowing water,excavating and carrying away material from the bed and banks of streams andfrom around the piers and abutments of bridges.

Scour has been the main foundations of failures of marine structures throughout the world. There are two types and from which are, contraction scours and local scour. However, we are local scour around pier in this research. Local scour is the removal of sediments from around bridge piers or abutment. Local scour around a bridgepier is one of the major possible cause of the hydraulic failure of a bridge.Local scour occurs because of the horseshoe current generated around the pierdue to abstraction to the flow.

LITRATURE REVIEW:

Several experimental techniques were applied to reduce the local scour around piers. These techniques are based either on strengthening the bed or altering the flow direction. Many researchers have conducted various studies to predict the maximum depth and diameter of scour hole. Vertical piles have been generally used in flumes to investigate the effects of scour. In a few studies, techniques to reduce the scour depth have been employed by making use of splitter plates and collars on the piles. Helical wires or cables wrapped spirally around the pile to resemble a threaded pile have also been used to reduce the scour. With the use of different special techniques, the scour depth has been reported to reduce by modifying the flow field near the piles. Prediction of scour depth is difficult as there are many uncertainties associated with it. Various methods of protecting the erodible soils around foundations of marine structures have also been adopted and such methods sometimes prove costly. It is therefore felt that more studies are still required to predict the scour depth effectively and also to find cost effective ways to reduce the scour.

PROBLEM STATEMENT:

Many bridges in our country faces sever local scour problems and about 80% of bridges fails due to scouring. Two approaches are applied to reduce local scour which are;

  • Altering the flow
  • Strengthening the bed

  We will apply altering flow techniques and will try to reduce scouring around bridge piers.

OBJECTIVES:

The main objective of LOCAL SCOUR AROUND BRIDGE PIER will be;

  • To compare local scour around square pier and diamond shape pier.
  • Experimental techniques to reduce local scouring.
  • To reduce local scour by altering the shape of pier.

METHODOLOGY:

Our research is experimental based, and we will adopt the following procedure;

  • The sediment bed throughout the entire depth will be leveled and compacted after the test file is installed.
  • The flume will be slowly filled with water and allowed to set for approximately 12 hours to allow air trapped in the sediment to escape. The flume is then drained, and the sediment compacted once again.
  • The velocity measurements from the two-electromagnetic flow meter will be checked periodically and minor valve adjustment made to maintain constant velocity. The reservoir elevation will be constant throughout the experiments.
  • The scour depth measurements from the transponders and video cameras will be plotted as a function of time to determine when near equilibrium scour depths are achieved.
  • When a near equilibrium scour depth condition is reached the flow will be slowly brought to rest.
  • The scour hole is then manually surveyed using a point gauge mounted to a traversing mechanism that allowed movements in the horizontal plane above the bed.

CONCLUSION:

Local Scour has been the major concern for bridge-pier safety of marine of sediments structures. pier due to numerous investigations by many researchers, the problem of scouring has not been effectively resolved yet. Though scour depth could be approximately predicted using various available ways, fool proof scour is yet to be achieved. Further studies are still required to correctly predict the scour depth and to find techniques to prevent or reduce the scouring a cost-effective manner to save the structures from the imminent danger of failure due to scour.

LOCAL SCOUR AROUND BRIDGE PIER,bridge scour scour depth 
LOCAL SCOUR AROUND BRIDGE PIER,bridge scour scour depth
LOCAL SCOUR AROUND BRIDGE PIER,bridge scour scour depth

Leave a Reply

Your email address will not be published. Required fields are marked *