This study will augment the research conducted on scour in cohesive soils. The study will address influence of large-scale turbulence on the erosion process of cohesive soils. Large-scale turbulence structures play an important role in the bridge pier scour process. The special erosion apparatus will be constructed to simulate the turbulent hydraulic loading on cohesive soil samples.
Scour development is especially complicated by the presence of large-scale turbulence structures. The roles that these turbulence structures play in pier scour have been only partially appreciated. Turbulence structures, together with local flow convergence/contractions, around the broad fronts and flanks of piers, or between piles of complex pier configurations, are erosive flow mechanisms of primary importance. This research study will apply various turbulent/dynamic hydraulic loading conditions to a range of different cohesive soils and will measure the soil erosion response. The oscillating hydraulic loading will be generated using a dual drive wave-making tube where soil samples can then be exposed to oscillating hydraulic loads . The soil samples in the test section are mounted on a sensor that simultaneously measures shear stresses and vertical forces. The erosion rate is determined through the loss of vertical force on the sample. The turbulent hydraulic loading is characterized by fluctuating/oscillating shear and normal forces. The proposed study is supported by HIBS-20 and the National Hydraulics Team. This research need was also identified by National Cooperative Highway Research Program (NCHRP) 24-27(1) as "Evaluation of Bridge Scour Research."