EXPERIMENTAL STUDY ON THE PERFORMANCE OF COARSE GRAIN MATERIALS AS SCOUR PROTECTION

Alexander Schendel, Nils Goseberg, Torsten Schlurmann

Abstract


Large scale hydraulic model tests were carried out to investigate the erosive potentials, bed stability and the performance as scour protection of wide-graded quarry-stone material with fractions ranging from 0.063 – 200 mm. Within the two phase test program the material was exposed to several wave spectra during hydraulic model tests in the Large Wave Flume of the Forschungszentrum Küste and additionally to an incrementally increased current in a closed-circuit flume at the Franzius-Institute. As result of the wave load, a maximum scour depth of S/D = 0.161 was observed after 9000 waves with a simulated storm duration of 20 h in model scale. Furthermore, fractional critical shear stresses were determined based on velocity measurements, which indicate highly selective incipient motion of individual fractions under steady current conditions. The selective mobility of this wide-graded material could not be expressed by the Shields approach.

Keywords


scour protection; hydraulic model test; wide-graded grain material; erosion stability; incipient motion; critical shear stress

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References


Andrews, E. D. (1983). Entrainment of gravel from naturally sorted riverbed material. Geological Society of America Bulletin, Vol. 94, 1225-1231.

Biron, P. M. et al. (2004). Comparing different methods of bed shear stress estimates in simple and complex flow fields. Earth Surf. Process. Landforms, Vol. 29, 1403-1415.

Carling, P. A. (1983). Threshold of coarse sediment transport in broad and narrow natural streams. Earth Surf. Process. Landforms, Vol. 8, 1-18.

CERC, Coastal Engineering Research Center. (2006). Coastal Engineering Manual. De Vos, L., et al. (2011). Empirical design of scour protections around monopile foundations. Part 1: Static approach. Coastal Engineering, 58, 540-553.

Det Norske Veritas, DNV. (2010). DNV-OS-J101 Design of Offshore Wind Turbine Structures.

Germanischer Lloyd, GL. (2005). Rules and Guidelines, IV Industrial Services, 2 Guideline for the Certification of Offshore Wind Turbines. Hamburg : Germanischer LLoyd, 2005.

Jain, S. C. (1990). Armor or Pavement. Journal of Hydraulic Engineering, Vol. 116, 436-440.

Kuhnle, R. A. (1993). Incipient motion of sand-gravel sediment mixtures. Journal of Hydraulic Engineering, 119.

Marion, A. and Fraccarollo, L. (1997). Experimental investigation of mobile armoring development. Water Resources Research, Vol 33, 1447-1453.

Melville, B und Coleman, S. (2000). Bridge Scour. Water Resources Publications, 2000.

Parker, G. and Sutherland, A. J. (1990). Fluvial armor. Journal of Hydraulic Research, Vol 28, 529-544.

Petrie, J. et al. (2010). Local boundary shear stress estimates from velocity profiles measured with an ADCP. River Flow 2010, 1749-1755.

Shields, A. (1936). Anwendung der Ähnlichkeitsmechanik und der Turbulenzforschung auf die Geschiebebewegung. Berlin : Eigenverlag der Preußischen Versuchsanstalt für Wasserbau und Schiffbau, 1936.

Shvidchenko, A. B. et al. (2001). Critical shear stress for incipient motion of sand/gravel streambeds. Water Resources Research, Vol. 37, 2273-2283.

Soulsby, R. (1997). Dynamics of marine sands - A manual for practical applications. Thomas Telford, 1997.

Sumer, B. M., Fredsøe, J., Christiansen, N. (1992). Scour around vertical piles in waves. Journal of Waterway, Port, Coastal and Ocean Engineering., 118, 15-31.

Sumer, B. M., Fredsøe, J. (2001). Wave scour around a large vertical circular cylinder. Journal of Waterway, Port, Coastal and Ocean Engineering, 127, 125-134.

Sumer, B. M., Fredsøe, J. (2002). The mechanics of scour in the marine enviroment. Advanced Series on Ocean Engineering . 2002, Volume 17.

Whitehouse, R. (1998). Scour at marine structures: a manual for practical application. HR Wallingford.

Wilcock, P. R. (1988). Methods for Estimating the Critical Shear Stress of Individual Fractions in Mixed-Size Sediment. Water Resources Research, Vol. 24, 1127-1135.

Wilcock, P. R. and Crowe, J. C. (2003). Surface-based Transport Model for Mixed-Size Sediment. Journal of Hydraulic Engineering, Vol. 129, 120-128.

Zanke, Ulrich C.E., et al. (2011). Equilibrium scour depth around piles in noncohesive sediments under currents and waves. Coastal Engineering, 58.




DOI: https://doi.org/10.9753/icce.v34.structures.58