Numerical simulation of bow thruster induced near-bed flow next to quay wall

During berthing operations of ships, the horizontal thrusters cause a hydraulic load on the quay wall and bed. This could eventually lead to scour holes in the bed, which may affect the structural integrity of the quay wall. This thesis is about a numerical simulation of a bowthruster jet which is deflected by a quay wall and the focus of this...

Experimental study on wave-induced scour in front of sloping coastal structures and the influence of bed protection

The erosion of the seabed in front of coastal structures induced by waves can lead to multiple types of failure instability or function of the structure. On this topic most research has been done into erosion in front of vertical structures. For sloping structures a knowledge gap exists in the understanding of the processes that lead to erosion...

Impact of scour on lateral resistance of wind turbine monopiles: An experimental study

The majority of offshore wind structures are supported on large-diameter, rigid monopile foundations. These piles may be subjected to scour due to the waves and currents that causes a loss of soil support and consequently decreases the pile capacity and system stiffness. The results of numerical models suggest that the shape of the scour hole...

Near-bed flow behaviour in scour holes under laterally non-uniform flow conditions

Recent research identified a novel scour-enhancing flow mechanism related to 3-D flow behaviour. Under specific conditions, vertical flow separation at the upstream crest of a scour hole can be suppressed as a result of lateral nonuniformities in the main flow. This so-called vertically attached flow state is associated with increased scour...

Experimental study on the influence of bed protections on scour depth and scour development in front of sloped embankments

On the seabed in front of coastal structures sediment movement takes place due to incoming waves. The erosion of sediments creates a scour hole at the toe of structures such as embankments, breakwaters and dikes. This scour hole may lead to instabilities in the main structure due to material sliding into this hole. A common method of protecting...

Modelling of wall-bounded flows near a cylinder-bed junction in turbulent flow conditions using an IDDES turbulence model to asses initial particle entrainment

Due to the presence of a monopile in a turbulent flow swirling vortices, known as horseshoe vortices, can form upstream of the structure near the cylinder-bed junction. Those vortices then travel downstream of the cylinder as they are being dragged along with the current. The horseshoe vortices can scoop up bed material surrounding the cylinder,...

Centrifuge modeling of the impact of local and global scour erosion on the monotonic lateral response of a monopile in sand

The majority of offshore wind turbines are founded on large-diameter, open-ended steel monopiles. Monopiles must resist lateral loads and overturning moments because of environmental (wind and wave) actions, whereas vertical loads tend to be comparatively small. Recent developments in turbine sizes and increases in hub heights have resulted...

Influence of scour depth and type on p–y curves for monopiles in sand under monotonic lateral loading in a geotechnical centrifuge

The influence of scour on the lateral response of monopile foundations for offshore wind turbines is investigated in this paper. Application of lateral load-displacement (p-y) curves to predict the lateral pile behaviour is subject to uncertainty as many of the presently used design approaches have been derived for long, slender piles. These...

Assessment of a storm surge barrier: A probabilistic fragility-based framework for the assessment of complex hydraulic structures

This thesis introduces a fragility-based framework in order to perform a custom assessment of the complex Eastern Scheldt storm surge barrier. By applying a conditional approach to loading parameters, the statistical dependency between failure mechanisms and structure elements can be described separately for the strength and loading part of the...

Probabilistic examination of the change in eigenfrequencies of an offshore wind turbine under progressive scour incorporating soil spatial variability

The trend for development in the offshore wind sector is towards larger turbines in deeper water. This results in higher wind and wave loads on these dynamically sensitive structures. Monopiles are the preferred foundation solution for offshore wind structures and have a typical expected design life of 20 years. These foundations have strict...

Recent development and remaining challenges in determining unique bridge scour performance indicators

There have been significant developments in the area of vibration-based bridge scour monitoring in recent years. Traditional scour monitoring using either visual assessment or diving inspections are now recognised to be very unreliable and highly subjective. There has been a concerted effort to move towards reliable systems capable of either...

Structural health monitoring for performance assessment of bridges under flooding and seismic actions

Bridges can be subjected to damaging environmental actions due to flooding and seismic hazards. Flood actions that result in scour are a leading cause of bridge failure, while seismic actions that induce lateral forces may lead to high ductility demand that exceeds pier capacity. When combined, seismic actions and scour can lead to effects...

Isolating the location of scour-induced stiffness loss in bridges using local modal behaviour

Detecting scour by analysing bridge vibrations is receiving an increasing amount of attention in the literature. Others have considered changes in natural frequency to indicate the presence of scour damage; however, little work has been reported on identifying the location of a scour hole based on vibration measurements. In this paper, a...

Development of scour in non-cohesive sediment under a poorly erodible top layer

The rivers in the South-West of The Netherlands flow over an erosion-resistant bed, consisting of peat and clay, overlying non-cohesive sediments. As they are experiencing general incision, the erosion resistant layer becomes thinner and sometimes locally breaks, exposing the more easily eroded non-cohesive sediments. Consequently sudden scour...

Modelling of Scour Depth at Quay Walls due to Thrusters

Introduction Inland and seagoing vessels are equipped with (bow) thrusters. The use of these thrusters can cause scour of the bed alongside a quay wall. In order to assess the consequences of local scour due to bow thrusters on the design of the structure it is desirable to know the dimensions of the scour holes as a function of in time....