Tests on new maintenance concept in the port of Rotterdam driven by mud rheology insights
CEDA Dredging Days 2015 - Innovative Dredging Solutions for Ports, Rotterdam
Geirnaert K, Staelens P and Deprez S - DotOcean, Belgium; Noordijk AC, Van Hassent A, Schot C and Rutgers R - Port of Rotterdam, the Netherlands
Abstract: Sedimentation is driving the maintenance process in a port. A guaranteed navigation depth is crucial for the proper functioning of the port and the safety of ships and their crews, and that in good relationship with the environment. Dredging is also often a dominant factor of expenditure in a port, regardless of its size. Faced with the economic and environmental constraints, the choice of dredging technique is essential. Finding a balance between cost, efficiency, and environmental impact drives ports to look for new maintenance concepts. In this paper we explain the path to implement a new way to measure and characterize the rheological characteristics of underwater sediment layers and support with this information an alternative dredging technique. The process consists of different steps.
The first action is to characterize the layers of mud throughout the access channel. With these data, a map is built with rheological and geotechnical properties of the mud. Based on the properties the volume of mud that can be fluidized and mobilized by a water injection technique is determined. The cutting depth of the low-pressure water jet can be calculated as well as the total impact zone that will be fluidized with a single water injection action. Secondly the seabed must be shaped and under the right conditions the sediment can then flow over the ground and be moved from one place to another.
The combination of the geotechnical and rheological characteristics of the sediment, the operation conditions of the WID dredger and the seabed shape allow to install a new maintenance concept in the Port of Rotterdam.
Key words: Water Injection Dredging, Sediment density flow, sediment rheology