Quantifying volume loss from rock penetration in sand during subsea rock installation, using a fallpipe vessel

In the field of offshore engineering, subsea rock installation has emerged as a pivotal technique. As offshore operations extend to greater water depths, the deployment of a versatile fallpipe has become a cornerstone for precise rock particle placement. A comprehensive determination of the overall rock material volume required for installation...

Cohesive Sediment Erosion Induced By Coandă-Effect-Based Polymetallic-Nodule Collector: Small-scale experiments

The increasing demand for rare minerals, such as lithium, cobalt, and copper, driven by the growth of the world population and the transition towards sustainable energy technologies, has become a pressing concern. These minerals are crucial for electrifying the transportation sector through electric vehicle production and are in high demand for...

Rock behavior in and below an inclined fall pipe

Subsea rock installation is an offshore engineering process where rocks are placed on the seabed as protection of cables and pipelines and as scour protection. The inclined fallpipebis a new piece of equipment specifically designed to install rocks close to submerged structures. This thesis investigates the processes of the rock flow in and...

Density wave amplification during long horizontal slurry transport: Experimental studies exploring mechanisms

This study is the first to experimentally show two wave mechanisms regarding density wave amplification with long horizontal slurry transport. There is bed-driven and suspended-driven density wave amplification, in which the grain size determines which mechanism is dominant.<br/><br/>Density wave amplification in hydraulic pipeline transport...

Stability Analysis of a Rapid Mechanical Lifting System for the Vertical Transportation of Polymetallic Nodules

Due to urbanization, improved living standards and electrification, approximately five times more raw minerals are necessary in 2050 compared to 2018. In deep oceans, the seafloor contains these minerals in the form of polymetallic nodules. Nodules are about the size of golf balls that grow throughout the ocean at depths between 3500 m and 6000...

Pile Dredging in Cohesive Soils: Experimental research on the influence of different dredging configurations

After decades of exploitation of hydrocarbons, the offshore facilities constructed for this purpose are nearing the end of their design life and/or economic operation. According to international law, these offshore structures need to be completely removed. Decommissioning of the substructures often requires for soil to be removed in piles to...

Subsea Tracked Trencher Mobility: The development of a model to gain insight of the moility of a subsea tracked trencher in granular and cohesive soils

The deployability, regarding mobility, of Boskalis trenchers, is currently determined by practical knowledge. The lack of theoretical knowledge means that risk assessments in the tender phase are less accurate. This reduced accuracy has two negative consequences. First, the trencher may fail. Secondly, the safety margins can be too large. Both...

Transient Slurry Flow Phenomena after Bends in the Vertical Plane: An experimental study and analysis into the origin and development of density waves within pipeline systems using a sedimentation and erosion unbalance model

Density waves inhibit the stability of (long) pipelines, which cannot be predicted using current day design tools. Density waves are formed due to an inverse relationship between sand eroding and settling in a pipeline. By designing and building a dedicated flow loop, an experimental study on how the erosion and sedimentation of sand in a pipe...

Plume dispersion of low-density clayey suspension turbidity currents created by deep-sea mining

Due to the increased demand for materials like cobalt and nickel, there is an interest to mine polymetallic nodules from the deep-sea. These nodules are abundantly distributed along the abyssal plains, e.g., the Clarion Clipperton Zone (CCZ) in the North East Pacific. These nodules lay spread on top of a seabed consisting of very fine clayey...

Dimpled channel flows: An experimental investigation into the drag performance of dimpled surfaces in turbulent channel flows

Drag in pipelines is composed almost solely of skin friction drag. The most common technique to achieve drag reduction (DR) is by adding drag-reducing agents. However, in the aerospace industry, various impressive passive drag-reducing techniques have been suggested to reduce skin friction drag in the past decades. Among these techniques,...

Adhesion factor and reduction methods for subsea cable ploughing in clay: An experimental study

Context: The shift to green energy offers a need for offshore wind farms. The transition from a relatively cheap energy production from carbohydrates, to a young offshore wind energy industry needs innovations to lower the cost. Increasing the efficiency of wind turbines and lowering the installation cost of a wind farm, will eventually make...

Subsea cable trencher performance on sand dunes: Numerical modelling of the waterjet trenching process and vehicle traction on sand dunes

Numerous offshore wind farms have been constructed recently in the southern part of the North Sea. Their infield and export cables are buried for protection against dropped or dragged objects. In sandy soils, it is common to use tracked remotely operated vehicles, equipped with two water jetting swords. These swords fluidise the seabed and...

Reduction of the outflow velocity of a closed fallpipe system: The concept selection and analysis of an outflow velocity reduction mechanism

Subsea rock installation is widely applied in the offshore industry and utilized for a wide range of purposes including but not limited to: pipeline protection, scour protection, insulation of pipelines, upheaval buckling prevention and seabed preparation. Tideway Offshore Solutions is specialized in subsea rock installation and currently...

Replacing the fibre optic cable between Vlieland and Terschelling

The cable between Vlieland and Terschelling needs to be replaced. The thesis focusses on the replacement of this cable. Because of the sensitive environmental situation some additional hurdles will need to be taken in order to come up with a decent placement plan.

A follow-up feasibility study to an amphibious spray pontoon

Beach nourishments or sand replenishments are applied by the use of pipelines or the rainbow method. Replenished sand is then moved and levelled by bulldozers. This is a passive approach to process the outflow of material. The land based equipment is dependent from tides and water levels, and significant effort is required to install and...