Dredging evaluation

Dredging preparation and evaluation

In the preparation of dredging projects, the sediment layers, depths, thickness and characteristics are important to estimate the dredging effort and power.
Ton Dry Weight
An important aspect to be monitored during maintenance and capital dredging works is the dredging volume and dredging mass. The latter is expressed in ‘Ton Dry Weight’. The volume and weight of the layer to be dredged helps to estimate the work load based on the capacity of the dredger. Acoustic methods can be complementary to determine the volume but do not give insight in the total weight of the layers to be dredged. The DensX can provide a very high accurate density profile of the underwater sediment layer. Based on this profile the Ton Dry Weight of the layer is visualized by the software.
Bed erosion
With the dotOcean GraviProbe and DensX system it is possible to accurately determine the characteristics of the sediment layers above the hard bottom. Density and sediment consolidation are parameters that will ensure a correct picture of the soil erosion and erosion capabilities and allow to support sediment transport studies.
Soil classification
The GraviProbe gives a sediment layer strength and soil classification. It is easy to find the interface mud/sand or mud/clay or mud/rock. Based on these inputs the type of dredging equipment can be selected and planned.
Water injection dredging 
To estimate a water injection dredging process the density measurement indicates how much water needs to be injected to reach a liquefaction point. The soil strength measurements indicate how deep the water beam will inject into the soil.
For more information on the applications: technical papers

Dredging data acquisition

With the dotOcean Atlantis platform it is possible to collect all output data of sensors and measurement systems with an accurate timestamp. The systems enhances the usability of onboard data in a cost efficient way. Online and real time streaming to network and visualization equipment, data management and system management are synthesized in a fast and easy-to-use platform.
Acoustic measurement systems, position sensors (GPS, compass), GraviProbe and DensX, weather data, mechanical measurements, detection sensors are parameters that can be easily processed and visualized in an integrated way by Atlantis.

Determination of nautical depth

When ships enter a port the navigability needs to be guaranteed. Since there is a continuous inflow of sediment in every port, regular dredging is necessary. Theoretically, the nautical bottom is the level where physical characteristics of the bottom reach a critical limit beyond which the controllability and maneuverability of a ship is not guaranteed.
A ship can navigate through fluid mud when density levels or rheological levels stay below a certain threshold. To determine when and how much there needs to be dredged to reach these levels, the underwater sediment and mud layers must be monitored and analyzed. The GraviProbe and DensX system are the perfect tools to accurately measure the density or rheological levels.

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