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Innovative free fall sediment profiler for preparing and evaluating dredging works and determining the nautical depth
Geirnaert, K.; Staelens, P.; Deprez, S.; Noordijk, A.; Van Hassent, A. (2013). Innovative free fall sediment profiler for preparing and evaluating dredging works and determining the nautical depth, in: CEDA 20th World Dredging Congress and Exhibition 2013 (WODCON XX). The Art of Dredging. Brussels, Belgium, 3-7 June 2013. pp. 11 pp
In: CEDA (2013). 20th World Dredging Congress and Exhibition 2013 (WODCON XX). The Art of Dredging. Brussels, Belgium, 3-7 June 2013. CEDA: Delft. ISBN 978-1-63266-266-8. 1043 (2 Vols) pp., more

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Keywords
    Density; Rheology; Shear strength; Marine
Author keywords
    Free Fall Penetrometer; Nautical Depth; Maintenance Dredging; Cone Penetration Resistance

Authors  Top 
  • Geirnaert, K.
  • Staelens, P., more
  • Deprez, S.
  • Noordijk, A.
  • Van Hassent, A.

Abstract
    There is a continuous inflow of sediments in ports and access channels and therefore maintenance dredging is necessary. To determine when and how much there needs to be dredged the underwater sediment and mud layers must be monitored and analyzed. This paper presents an innovative vertical profiling techniquemeasuring in a single free fall trajectory the depth, thickness, density and strength of underwater sediment layer. The instrument operates in free fall and impacts underwater sediment layers. During impact it measures penetration resistance and pressures.The technique can be used in several aspects of the dredging process. In combination with acoustic methods like multibeam echo sounders it is used to visualize the sediment layers under a multibeam surface. Another important aspect of soft sediment is the navigability. Ships can navigate through loose mud layers if the physical characteristics of the mud stay below a critical limit. Today the measured physical characteristic in many ports is density. Density was historically chosen as a substitute for strength. The proposed measurement technique allows visualization of a density and a strength profile and enables ports to evaluate alternative nautical depth criteria.

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