25/05/2018 11:00 - Amphi H
Pr. Weiming Wu, University of Clarkson
Noncohesive sediments (such as sand and gravel) move as individual particles, whereas cohesive sediments (clay and silt, <~0.01 mm in size) usually erode and transport in flocs that consist of particles irregularly bonded by interparticle electrostatic forces. When cohesive and noncohesive sediments are mixed, interactions between them add more complexity in the erosion and transport processes. The erosion characteristics of the mixed sediments highly depend on the relative composition and packing structure of fine and coarse particles, as well as the compaction of fine particles. This seminar presents recent studies on the critical shear stress and erosion rate coefficient of mixed sand and mud. The experiments were conducted in a SEDFlume, which has a conduit test section of 100 cm long, 10 cm wide, and 2 cm deep. It is found that the critical shear stress is a function of the critical shear stresses of pure sand and mud, mud content and sand diameter. The erosion rate and bed shear stress follow a nonlinear law. The erosion rate coefficient has a strong correlation with mud content and mud dry density.