Properties of a Novel Local Scour Protective Equipment Around Pile of Marine Bridge Under Wave Action

Piles are widely used in practice to support marine bridge structures. However, scour around piles may reduce the stability of bridge structures. In the present paper, novel protective equipment is developed to reduce local scour around bridge piles under coastal environment. The equipment is composed by a collar on the top and a protective tube with rows and columns circle holes on the surface of tube. Series of wave flume model tests are performed on single pile to study the properties of the new equipment based on the principal of similarity. Wave flume experiments are carried out in a wave flume with a test section of 1.4 m wide, 1.0 m deep and 17.3 m long and a 4.8m long and 0.50m deep sand bed section is installed in the middle of the wave flume. The test system is comprised with wave monitors and an endoscope detector for scour depth. Regular waves are generated by the wave maker in wave flume. Properties of local scour around pile with or without the protective equipment are compared by means of experimental method. As a result, the maximum erosion depth around the pile is in direct proportion to the wave height, wave length, and pile diameter, but in inverse proportion to water depth and collar diameter. It is concluded that the protective equipment present here can reduce the depth of local scour around the pile effectively on basis of the experimental results. A moderate height of protective device is benefit for reduction of scour.