Dimensionless critical shear stress evaluation from flume experiments using different gravel beds

✍ Scribed by F. Petit

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 896 KB
• Volume: 19
• Category: Article
• ISSN: 0360-1269
• DOI: 10.1002/esp.3290190608

✦ Synopsis

Flume experiments were conducted using four different gravel beds (Dso = 12-39 mm) and a range of marked particles (1 0-65 mm). The shear stresses were evaluated from friction velocities, when initial movement of marked particles occurred. Two kinds of equations were produced: first for the threshold of initial movement, and second for generalized movement. Equations of the type 6, = u ( D ~/ & ) ~, as proposed by Andrews (1983) are applicable even if the material is relatively well sorted. However, the values of a and b are lower (respectively 0.050 and -0.70) for initial movement. Generalized movement requires a higher shear stress (a = 0.068 and b = -0.80).

D9o of the bed material and yo (the bed roughness parameter) were also used as reference values in place of Dso. They produced lower values than in natural streams, mainly owing to the fact that the material used in the flume is better sorted: clusters are less well developed and the bed roughness is lower.