This study investigates the seasonal deformation behaviour of the Noordtunnel, an immersed tunnel near Rotterdam, Netherlands, based on 461 days of continuous deformation monitoring data collected across 22 structural joints between July 2024 and October 2025. While preliminary evidence of temperature-induced deformation in the Noordtunnel has been identified in prior work, its further analysis and safety implications have remained open. This thesis addresses the gap in characterising the Noordtunnel's seasonal deformation behaviour to identify the main external drivers, reconstruct the tunnel’s total deformation profile, quantify the lag and spatial sensitivity of the structural response, and assess the impact of seasonal deformation on joint watertightness and structural safety.

Data decomposition and frequency domain analysis show that joint deformation varies strongly with season, with clear annual and daily cycles that are related to temperature changes. Longitudinal joint deformation has a strong negative correlation with temperature, with an overall correlation of -0.93 and thermal sensitivities between −0.135 mm/°C and −0.229 mm/°C, with the roof opening being the most sensitive area. Tidal fluctuation has a negligible influence across all deformation directions. Temperature has a relatively weak influence on vertical deformation, while transverse deformation appears independent of any external drivers. At the local joint level, longitudinal thermal lag-response is nearly instantaneous, while at the system level, it has a 1-day lag.

Attempts to reconstruct the total deformation profiles using chain calculations that account for joint rotation still produce large closure errors, up to -2492 mm in the winter period. Correcting the pitch angle rotation contribution reduces the closure error by 83.5\% during extreme winter, with a mean reduction of 76\%, although the error remains. The impact of seasonal joint opening on the tunnel’s joint watertightness and rotation failure is found to be minimal. At the immersion joint, the GINA watertightness evaluation has the lowest Safety Factor of 11, while at the dilation joint, the joint opening is below the 15 mm threshold. The joint's pitch angle rotation is also below the tunnel's joint rotational capacity of 2 mrad. However, the large joint opening in Joint 13, with an amplitude of 7.9 mm, is related to the previous leakage at this location. It is suggested to further examine the structural condition of tunnel joints with a similar joint opening amplitude. ... Read more

Clinker production for concrete is one of the largest sources of anthropogenic CO2 emissions worldwide. Excessive carbon emissions drive global climate change, prompting widespread efforts to reduce industrial environmental impacts. This has driven the use of alternative binder materials, among which geopolymer concrete is a prominent candidate. Geopolymer concrete exhibits enhanced durability in aggressive environments, making marine jetty structures a potentially favourable application. This thesis assesses whether this potential translates into tangible structural, environmental, and financial benefits at the project level. As a reference case, an existing jetty in the Port of Rotterdam was redesigned into two geopolymer variants: a partial geopolymer design (in-situ topping layer only) and a full geopolymer design (all concrete elements). Both variants were verified structurally against identical requirements using a semi-probabilistic approach in SCIA Engineer, with environmental and cost data sourced from Witteveen+Bos and the Rotterdam Port Authority.

The study demonstrates that both geopolymer designs are structurally viable. Improved durability enables a reduction in concrete cover, decreasing the total concrete volume of the full geopolymer design by approximately 5%. In the partial design, however, differential shrinkage and creep between the concrete types creates a governing load case that offsets the durability benefit, requiring a slight material increase. At the whole-structure level, both designs reduce equivalent CO2 emissions by 2% and the Environmental Cost Indicator by 8% relative to the reference design. These modest reductions reflect the dominance of the steel foundation piles, which govern the footprint regardless of concrete choice; evaluated at the concrete element level alone, the savings are substantially higher. Both geopolymer designs increase total costs, by 3% for the partial and 8% for the full design, yielding reduction costs of €2 and €3 per kilogram of CO2 reduced, respectively. Sensitivity analyses show that seismic activity and rebar ratios have a negligible impact, whereas the financial competitiveness between variants hinges on the geopolymer price premium: below €25 per m3, the full design offers lower cost per unit of CO2 reduced, while above this threshold, the partial design becomes more favourable to justify. Overall cost parity requires roughly halving current geopolymer prices. Crucially, raw material supply (primarily blast furnace slag) is already constrained and projected to decline further as steelmaking shifts to hydrogen. Thus, while geopolymer concrete is a viable solution for specific, high-durability marine applications, its limited supply chain restricts its broader role in decarbonizing the construction sector. Future research should prioritize larger-scale, long-duration testing to validate these findings. Furthermore, practitioners pursuing real-world applications of geopolymer concrete for the sake of environmental improvements must critically evaluate the system-level availability of these precursor materials before committing to project-level adoption.
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This thesis investigates which quay wall configuration is geotechnically most suitable for Energiehaven IJmond, where adjacent spudcan penetration, heavy operational quay loads and controlled steel slag containment must be considered together. Energiehaven IJmond is planned as an offshore wind terminal for storing, handling and loading heavy wind turbine components. This function requires high operational quay loads and allows wind turbine installation vessels to operate close to the quay. During these operations, the vessel legs penetrate the harbour bed through spudcan footings, which can disturb the soil near the quay and change the load path acting on the quay wall. The project also creates a possible reuse route for steel slag from the nearby Tata Steel plant, provided that expansion, leaching and containment can be controlled.

A three-loop design process was used. The first loop reduced the initial longlist to a caisson wall, a standalone combined wall and a combined wall with relieving platform. The second loop used preliminary hand calculations to check the technical feasibility of these three concepts. The standalone combined wall was eliminated because the calculated bending moments and anchor forces did not lead to practical member sizes. The third loop used PLAXIS 2D to model the selected caisson concept under the governing operational load combination and adjacent spudcan loading. The caisson was selected for numerical modelling because it gives the clearest route for controlled steel slag containment and because its use for this terminal type is less established than a combined wall with relieving platform.

The PLAXIS 2D calculations show that the 20 m fully ballasted caisson derived from the preliminary design is not suitable as a final geometry under the adopted load situation. Increasing the caisson width to 25 m and reducing the water-side ballast bring the calculated response below the adopted displacement limit. Adjacent spudcan penetration does not govern the global caisson displacement in this model. The load-equivalent pressure and penetration-depth soil-removal representations add only about 4% to the displacement already mobilised by the operational load state. The spudcan effect remains relevant for local soil response, penetration depth, vessel selection, spudcan-to-wall distance and the local load path.

The PLAXIS model does not prove that steel slag can be reused safely. Expansion, leaching, drainage behaviour and material compatibility require separate material and environmental checks. A widened and rebalanced caisson is therefore preferred when controlled steel slag containment governs the design choice. A combined wall with relieving platform remains the more conventional alternative when steel slag reuse is secondary to reducing concept uncertainty under heavy operational quay loads.
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Deep excavations change the effective stress field in the retained ground, which may lead to horizontal deformations of the pile, a reduction in axial pile bearing capacity and an increase in settlement for foundation piles adjacent to the excavation. However, it is not yet well understood how and to what extent these mechanisms develop in practice. This thesis investigates how excavation-induced stress changes and soil movements affect the behaviour of a single displacement pile and how these effects can be incorporated into a simplified design method.
The main objective of this research is to create a simplified design method for piles adjacent to a deep excavation. First, a calibrated three-dimensional finite element model is developed in PLAXIS 3D, in which pile–soil interaction and installation effects are represented and matched to NEN/Koppejan capacity calculations. A parametric study investigates the influence of pile–wall distance, pile length, wall embedment depth, and wall stiffness. Additional cases consider a clay layer overlying sand, in which prior settlement is imposed to introduce an initial state with negative skin friction present on the pile. Simplified methods, including PLAXIS 2D and D-Pile Group, are evaluated against the 3D reference model.
The results show that capacity loss is governed primarily by a reduction in horizontal effective stress within an excavation influence zone, leading to a decrease in mobilizable shaft resistance. Base resistance is affected when the pile tip lies within this zone. In the presence of a compressible layer, which can lead to negative skin friction on the pile over time, excavation-induced settlements increase relative pile–soil displacement which results in additional negative skin friction at working load levels.
Based on these findings, a simplified design method is proposed, in which excavation effects are represented by a primary and secondary excavation influence zone based on the friction angle, horizontal extent of the excavation induced surface settlements and vertical extent of the change of effective stress. Within each zone, reduction factors are applied to the shaft resistance, and where relevant to the base resistance. These reduction factors account for the excavation-induced capacity loss. The study is limited to a single displacement pile, idealised soil profiles, and simplified installation effects.
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The City of Galveston, Texas, has faced repeated hurricane damage, notably from the 1900 Great Galveston Hurricane and Hurricane Ike in 2008. Existing protection, mainly the Galveston Seawall, is insufficient to prevent flooding from storm surge, especially under sea level rise. Along with their plan to raise barrier islands and close off inlets to prevent water coming into the Bay, the U.S. Army Corps of Engineers (USACE) proposed a Ring Barrier consisting of floodwalls and levees to protect Galveston specifically. However, its alignment through developed areas raises concerns over port access, required pump capacity, operational reliability of traffic gates, and future city expansion.
This design study develops three alternative surge protection strategies that seek alleviate the concerns raised for the USACE Ring Barrier, along with protecting the port of Galveston, which is located between Galveston Island and Pelican Island, from storm surge.

Strategy 1 keeps to Galveston Island, placing the road that roughly separates the port terminals from the commercial/residential areas, Harborside Drive, on a levee to avoid the need for traffic gates. Local resilience measures for port terminals, particularly cruise facilities, are proposed to minimize damage and recovery time.
Strategy 2 avoids the developed area on Galveston Island by including the port area inside the protection, reducing required pumping capacity. This would entail two large-scale storm surge barriers at both entrances to the port basin to ensure port accessibility, and a levee around the current development on Pelican Island.
Strategy 3 expands on strategy 2 by including a larger part of Pelican Island, undeveloped as of yet, in preparation for future developments.
The expected reduction in flood risk over structure lifetime and performance on criteria other than cost for strategies 2 and 3 is deemed insufficient when compared to strategy 1. The preferred strategy of the 3 developed is therefore strategy 1, keeping the main protection to Galveston Island, and protecting the port with local measures. ... Read more

This thesis presents a comprehensive investigation into excavation-induced swelling in soft clay soils, with a specific focus on the influence of embedded structural elements and pile installation effects. The motivation for this research stems from the conservative nature of
traditional analytical methods, which tend to overestimate swelling due to their simplifying assumptions—highlighting the need for a simple yet more advanced modeling approach that captures soil-structure interaction more realistically. The research integrates both analytical and numerical methods to assess vertical deformation and swelling pressure under varying geotechnical configurations. The analytical approach employs the Koppejan method, a classical consolidation-based method, to estimate heave resulting from dissipation of excess
pore water pressure during the last phase of consolidation. Implemented in Excel, the analytical model assumes idealized elastic soil behavior and uniform unloading. This method serves as a
baseline for identifying trends and quantifying the level of conservatism in traditional estimates.
The numerical simulations are carried out using PLAXIS 2D, applying the Hardening Soil model to realistically capture the nonlinear behavior of soft clay. Various scenarios are modelled, including the presence or absence of floor slabs, embedded piles, and volumetric
expansion resulting from pile installation. Volumetric expansion is introduced via prescribed initial strains, mimicking the stress redistribution caused by displacement-type pile installation.
Five structured cases are developed to isolate and analyse the effects of pile stiffness, spacing (centre-to-centre distances of 2 m and 2.5 m), floor rigidity, and interaction effects.
Results demonstrate that analytical methods consistently overestimate both swelling displacements and floor swelling pressures by up to 70% in some configurations due to their
inability to account for soil-structure interaction and stress redistribution. Numerical findings highlight that embedded piles, particularly when closely spaced and combined with stiff floor
systems, significantly reduce the magnitude of swelling and associated pressures. Additionally, pile installation effects play a vital role in stress buildup, altering pore pressure dissipation and
influencing upward soil movement.
This dual-framework approach offers critical insight into the mechanisms driving swelling in excavation contexts and provides practical guidance for improving predictive accuracy in
design. The outcomes underscore the necessity of incorporating installation effects and realistic structural modeling in modern geotechnical practice. ... Read more

The Netherlands are prone to flooding, with 30% of the country lying below sea level. To protect its densely populated and economically important coastal zone, Rijkswaterstaat (RWS) applies a maintenance strategy based on regular sand nourishments. These nourishments involve the placement of large volumes of sand, typically dredged from the North Sea seabed, to compensate for structural erosion. While this process is effective for maintaining coastal safety, it is resource-intensive and increasingly unsustainable in light of climate change, sea-level rise, and stricter environmental ambitions. With national coastal programmes such as Kustgenese 2.0 and the Dutch Coastline Challenge calling for more sustainable and adaptive maintenance strategies, complementary alternative concepts are under consideration. One such concept is sand recirculation: the artificial redistribution of sand within the coastal system, without the need for additional offshore extraction. Internationally, this principle is already applied through various forms such as sand bypass systems, which transport sediment along the natural littoral drift to counteract obstructions like jetties; sand backpass systems, which move sediment against the dominant transport direction to replenish eroding areas; and periodic dredging campaigns, where accumulated sediment is relocated within the same littoral cell. These systems respond to sediment imbalances caused by human interventions and offer a sustainable alternative in settings where offshore resources are limited or environmental impacts must be reduced. This thesis explores whether such a recirculation strategy can be a technically feasible addition to the nourishment policy at Maasvlakte 2. This protruding coastline, located on the western boundary of the port of Rotterdam, experiences a structural morphological imbalance: persistent erosion in the westfacing bend and visible accretion in the southern section (in the form of a spit), primarily due to strong gradients in alongshore sediment transport. Currently, large-scale nourishments from offshore sand sources are periodically used to reinforce the eroding zones. However, the simultaneous accumulation of sand in the south offers potential for a circular approach to sediment management. This study aims to evaluate whether this locally available sediment can be redistributed to erosion-prone areas through artificial means, thereby reducing the demand for traditional offshore sand sources. The research begins with a morphodynamic analysis of Maasvlakte 2, using various datasets including bathymetric surveys, coastal profile data, and shoreline extractions. Accretion and erosion patterns were quantified and compared to predictions made using the one-line ShorelineS model, which simulates coastal evolution based on alongshore transport driven by transformed offshore wave conditions. This comparison confirmed that the largest erosion hotspot coincides with the western bend of the coastline, while the southern section consistently accumulates sediment. An additional finding, which was not initially anticipated, is the identification of a secondary accretion hotspot that may serve as a viable source area for sand recirculation. This results in the presence of both a southern source (the spit) and a northern source, each subjected to distinctly different hydrodynamic conditions and therefore requiring a distinct approach to extract sediment from these respective hotspots. Annual redistribution volumes between 300,000 and 415,000 m³ were identified as potentially technically recoverable, equating to a reduction of approximately 42-59% in the need for offshore-originating sand nourishments. Several operational strategies were explored, including the use of trailing suction hopper dredgers (TSHDs), cutter suction dredgers (CSDs), and sand backpass systems, in which sediment is transported continuously through pipelines. For each strategy, design parameters such as dredging volume, frequency, location, and required vessel or system dimensions were assessed. A Multi-Criteria Analysis (MCA) was used to evaluate each option based on technical feasibility. The evaluation revealed that a TSHD is the most suitable option for the northern source, while a CSD is preferred for the southern source. This distinction arises from the deeper location and greater flexibility requirements in the north, which suit the mobile operation of a TSHD. In contrast, the southern site allows for more precise, ii iii stationary excavation nearshore, favouring a CSD in combination with barge transport. In a subsequent multi-criteria analysis that considered operational feasibility, costs, and other relevant factors, the TSHD and the sand backpass system emerged as the most favourable options for their respective locations. The greatest technical complexity lies in the redistribution of sediment within the western bend of Maasvlakte 2, where bi-directional sediment transport dominates. This area requires nourishments to be placed across a wide spatial range and over varying water depths, posing significant operational and morphological challenges for any recirculation strategy. Although the research is limited to a pre-feasibility level, the results indicate that artificial sand recirculation could reduce reliance on offshore resources while maintaining coastal safety at the Second Maasvlakte. However, legal and regulatory barriers remain, as current Dutch legislation restricts the reuse of dredged material in water depths smaller than 20 meters for nourishment purposes. Moreover, the influence of cross-shore processes and seasonal transport variability, especially under tidal forcing, remains uncertain and would require further investigation. This thesis concludes that sand recirculation at the Second Maasvlakte is potentially technically feasible under the studied conditions and has the potential to serve as a sustainable addition to the Dutch coastal maintenance strategy. Its implementation depends on careful system design, regulatory reform, and alignment with broader environmental goals. Further research is recommended to optimise operational parameters and develop integrated system concepts that satisfy the demands of both coastal managers and other stakeholders. ... Read more

The goal of this research is to understand the impact of the Delta21 construction on the hydrology and morphology of the current situation. Such understanding helps reveal how the system moves toward a dynamic equilibrium, which is crucial for developing a stable tidal lake. The study employs numerical modeling using Delft3D to simulate the hydrodynamics and sediment transport within the system. The effects of the inlet width and hydraulic forces on sediment transport and bed evolution are investigated to identify how these factors control erosion, sedimentation and long-term morphological changes.

The model focuses on three main hydraulic forces: tidal motion, river discharge, and operational flows from pumps and turbines. To simplify the system, wind and wave effects are excluded, as the Delta21 construction largely protects the tidal lake from incoming waves. A representative tide is imposed, neglecting spring–neap tidal variability, and river discharge is held constant at 1000 m³/s. Pumps and turbines are modeled using maximum discharges rather than realistic fluctuating operations. The sediment transport is limited to sand with a median grain size of 160 µm, with only a single hydrodynamic layer and one active sediment layer. These simplifications allow the study to capture general morphodynamic trends while recognizing that small-scale and those involving finer sediments or varying tides and river flows, are not resolved.

Results show that inlet dimensions critically control flow velocities and sediment dynamics. Narrow inlets accelerate flow, causing substantial erosion, while wider inlets reduce velocities and promote deposition. Because the inlet is a fixed hard structure, the width cannot adjust naturally; the only way for the system to increase the inlet cross-section is by eroding its bed. The equilibrium depth emerged as a key concept: it represents the depth at which erosion stops. Once this depth is reached, cumulative sediment transport patterns indicate that the system may begin importing sediment from outside, suggesting a potential shift toward flood-dominant behavior. In the simulations, only the 2000 m inlet without river discharge approached equilibrium and showed signs of flood-dominant sediment transport. The 1500 m inlet eroded toward equilibrium but had not yet shifted to flood dominance, while all scenarios with river discharge remained ebb-dominant, exporting sediment.

Future developments, such as sea level rise and increasing extreme river discharges, influence morphological stability. Sea level rise drives long-term sediment loss, whereas extreme discharges induce short-term sediment redistribution inside the tidal lake. These findings highlight the importance of designing inlet dimensions to maintain flow velocities near the critical threshold for sediment transport and of understanding equilibrium depth dynamics to guide the system toward long-term morphological stability.

In conclusion, the research demonstrates that inlet geometry and hydraulic forcing strongly influence the morphodynamic evolution of the tidal lake. Simplified numerical models, informed by natural system analogies, can effectively support the design of engineered tidal lakes and provide insight into the hydrodynamic and morphodynamic processes that control inlet evolution, sediment transport, and overall system stability. ... Read more

The growing demand for digital infrastructure presents the Netherlands with spatial and energy-related challenges. The objective of this study is to develop a functional and structural design of a support system for a floating hyperscale data center located on the Delta21 energy storage lake. The goal is to assess whether such a floating system can be realized as structurally safe, dynamically stable, and spatially compatible within specific boundary conditions. The study follows the methodology of the elementary design cycle, progressing from problem definition to verification. First, the functional design consisting of a rectangular pontoon anchored by rigid steel mooring arms was developed.

After verification of the boundary conditions, functional requirements, and evaluation criteria obtained from the system analysis and listened in the Basis of Design, the functional design is shown to be feasible at this design phase. The three main functional challenges were that the structure must continuously accommodate water level variations of up to 25 m, that it must provide a reliable support structure for the data center equipment, and that the structure is located within Natura2000 areas.

For the proposed functional design, a structural design was developed. Static and dynamic analyzes were performed to establish a preliminary understanding of feasibility and structural behavior. A first order static analysis of horizontal wind loads demonstrates that the structure remains within allowable limits for both mooring arm strength and pontoon stability. Regarding the dynamic stability of the pontoon under environmental loads, no definitive conclusions can be drawn because the analysis indicates sensitivity rather than the actual response of the system. The results suggest that the system is likely to be susceptible to resonance from wind gusts. Therefore, structural feasibility has been partly demonstrated, but structural reliability cannot yet be assessed.

Currently, there are no standard design guidelines or reference projects for floating data centers. Consequently, the model was developed on the basis of assumptions derived from related maritime and offshore engineering practices and guidelines. Therefore, a sensitivity analysis was performed to provide additional insight into possible design optimizations. This analysis also indicated that the system is sensitive to vertical instability. Further studies can therefore challenge the proposed design and could even undermine its performance. The results should therefore be regarded as an initial technical exploration rather than a fully validated design.

The study concludes that the proposed concept is structurally robust, functionally feasible within this design phase, and future-oriented. Integrating a floating hyperscale data center into the Delta21 project combines digital capacity, sustainability, and spatial efficiency. For subsequent design phases, it is recommended to make iterations on the proposed design and to investigate the economic feasibility, environmental impact, and energy integration to fully assess the overall feasibility of the project. ... Read more

Immersed tunnels are underwater structures consisting of prefabricated elements that are floated to the construction site and then immersed in place. These elements are typically composed of segments, with all structural connections between the segments and elements formed by shear joints or the shear keys. These shear connections are essential for restricting movement within the tunnel, ensuring both waterproofing and structural safety. However differential settlement, a common issue in such structures can introduce significant shear forces within these joints, posing a threat to the tunnel’s structural integrity. The performance of these shear joints is heavily influenced by the complex interactions between the tunnel and the foundation. The foundation and subsoil stiffness variability plays a critical role in differential settlement between adjacent tunnel elements, thereby directly impacting the performance of the shear keys.
The existing design methodology for the shear joint design used in Fehmarn Belt project, rely on techniques like Gaussian random field, Monte Carlo sampling, and joint statistics in the post processing
to model the influence of the spatial variability. While these methods provide detailed insights into the effects of spatial variability, their complexity, and the time intensive nature of their application could effect the timely delivery for large scale projects where efficiency is paramount. Thus, the main objective of this thesis is to develop a simplified approach to Soil-Structure Interaction (SSI) analysis that remains effective without the cumbersome detail of the existing design methodology. The purpose of this simplified approach is to offer a reliable alternative to the existing SSI methodology used in the Fehmarn Belt project.
The approach presented in this thesis simplifies the modelling of the combined stiffness variability of the subsoil and gravel bed beneath the tunnel. This approach utilizes a multi-linear Winkler Spring model. The soil stiffness parameters are derived from the CPT-NEN approach, and the combined stiffness variability of the subsoil and gravel bed is calculated using the spring-in-series equation. The soil
deformations, simulated in PLAXIS 2D, are translated into springs using the multi-linear Winkler Spring approach. This simplification forms the basis for the subsequent analysis performed in SCIA Engineer
software, where joint shear forces are calculated under various stiffness variability schemes and load levels.
The thesis concludes by comparing the shear response of the simplified approach with those obtained from the complex soil-structure interaction design in the Fehmarn Belt project, validating the reliability of the used approach in terms of safety. The comparison demonstrates that within acceptable tolerances, the simplified approach produces reliable results for the considered design conditions, taking into account the scope defined in the thesis.

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The Dutch system of waterways, of which the River Waal is the largest, allows for transport of cargo via inland navigation. Inland navigation as a transport mode contributes to the Dutch GDP and is indispensable for the Dutch strategic position in international world trade. Because inland navigation is river-based, it is dependent on natural conditions. Recent periods of drought, such as in 2018, have led to major financial impacts in the Netherlands and Germany. Due to climate change, periods of drought are expected to be more frequent, longer and more extreme in the future. Given the importance of inland navigation, measures are sought after to counteract these effects of climate change. Canalization of the River Waal is a last resort infrastructural measure to gain control over water levels on the river. To date, it is unclear whether climate change will eventually make it necessary to canalize the river for the benefit of inland navigation. In addition, it is unknown on the basis of what considerations such a decision should be made. This research attempts to answer these questions.

To investigate the necessity of canalization due to climate change, first the impact of climate change on inland shipping is determined on three different levels. First the hydrological development including occurrence of (low) discharges and corresponding water depths. Second the impact on individual vessel's loaded draught and loading rate, based on least available water depths on the River Waal in climate scenarios. Third the corridor cargo transport capacity, based on the occurrence of (low) discharges and the cargo transport performance of inland shipping in the past 10 years during similar discharge events. The development of these elements are the considerations in the debate on necessity of canalization of the River Waal from a shipping perspective. Whether these developments support the necessity of canalization is studied by means of limits which, if exceeded, may argue canalization. For the river's navigation function, requirements on navigability were identified based on prevailing international waterway management regulations (CCNR and TEN-T) as well as on previous Dutch canalization projects on the River Meuse and Lower-Rhine. The limits are projected on the analysed future development of the River Waal under climate change, to identify if and when they are met.

The hydrological development of the River Waal is assessed based on future discharge projections at Lobith under climate change. A range in scenario's is described, with a low emission and wet climate scenario 'Ln' on one side and a high emission and dry scenario 'Hd' on the other. In an Ln scenario, the future occurrence of days with low discharges (<1800 m3/s) on average per year is similar to that of the reference scenario (past 30 years, 1990 - 2020). In contrast, an Hd scenario shows a steady increase in the days of low discharges until 2100 after which the trend stabilizes. Extreme low discharges <600 m3/s appear. Furthermore, the lowest annual discharge (generally speaking during summer) lowers to 1000 m3/s by 2150, which is 750 m3/s lower than in the reference scenario.

At Rhine Kilometer 885 near Nijmegen the lowest water depths occur. In an Ln scenario the number of days with low water depth (<2.8 meter) is similar to the reference scenario with 40 days, independent of time. In the Hd scenario the number of days with low water depth increases where <2.8 meter occurs up to 3x more as in the reference scenario and outliers of <1.6 meters appear, up to 10 days. The long term average lowest discharge during the year drops from 3.5 meters in the reference scenario to 3 meters in 2050 and <2.5 meters after 2100.

The analysis of discharges and water depths is used to describe the development of the transport function of the River Waal. The location with the lowest water depth on a route of a vessel determines the loading rate. The combination of loading rate and active fleet determines the total amount of cargo carried on a corridor. In an Ln scenario, there is little deviation from the reference scenario, but nonetheless, a large vessel 135x17.4 meter CEMT Class VI+ has a restricted loading rate for 7 months per year with a minimum of 50% of the maximum vessel loading capacity. In an Hd scenario the loading rate of vessels decreases and the period lasts longer. For a most common vessel 110x11.4 meter CEMT Class Va, an annual average minimum is observed of 60% in 2050 to 40% in 2150. The duration of restricted loading doubles and the steepest decline is observed between 2050 and 2100.

Based on historical performance (2010-2020) of inland navigation, linked to the occurrence of discharges, a first-order indication of the development of transport performance over the River Waal corridor under climate change is made. No absolute numbers can be determined on this basis, but a sense of trends can be obtained.

Assuming no changes in the current fleet, the annual total weight that can be transported will decrease regardless of the climate scenario. The severity does depend on the climate scenario. Zooming in on cargo type does show a varying picture, where for dry bulk cargo there is an annual decrease of -3.0% cargo transport capacity in the most severe 2150 Hd scenario, while for liquid bulk cargo there is a steady decrease to -12.0% cargo transport capacity in 2150. This difference is explained by the number of trips made, where for dry cargo this theoretically rises to +25% in 2150 Hd, while for liquid cargo it can only increase +3%. Redundancy in the fleet can thus partially counteract the effects of climate change.

To reason the necessity of canalization, limits on navigability are identified, based on current navigational requirements and previous canalization practice. For the river's transport function, no clear limits where found, as a result of which no development could be identified that necessitates canalization. There are two regulations that apply to the navigability of the River Waal. TEN-T is a transport policy of the European Union and sets requirements for the quality of its network. On the River Waal, a guaranteed draught of 2.5 meters is required year-round. This is not met in the present (20 days undershoot in an average year) and will not improve in any climate scenario (up to 80 days in 2150 Hd). The CCNR is an association of five countries that is committed to the safety and interests of inland navigation on the Rhine. CCNR guidelines are leading for river management in the Netherlands. On the River Waal, 'OLR' (Agreed Low River Level) conditions require a water depth of 2.8 meters in the fairway, per definition a water depth that is undershot on average 20 days a year. This is not met in the present (40 days undershoot in an average year) and will not improve in any scenario in the future (>100 days in 2150 Hd).

Conditions on the River Meuse (1920) and Lower-Rhine (1960) before canalization were projected onto the present River Waal. If, as on the River Meuse, one want to accommodate a normative vessel CEMT VIc 6-barge push barge, there is at least 180 days of loading rate restrictions, now and in the future under all considered climate scenarios. The Lower-Rhine is canalized for the purpose of navigability of Lower-Rhine and River IJssel and to control freshwater distribution. Both Lower-Rhine and River IJssel did not meet the navigability requirements set at the time. The River Waal also does not meet its current stated navigability requirements (CCNR 2.8m: 40 days), but even in the extreme 2150 Hd scenario this is roughly only half (100) of the days as on the River IJssel and Lower-Rhine (2.7m: 190 and 225). The navigability requirements of that time did fit better with the draught of a most common vessel. The current most common vessel 110x11.4 meter CEMT Va experiences as many days (160) of insufficient water depth as on the River IJssel in all dry climate scenarios between 2033 and 2050. Compared to the Lower-Rhine, this is the case in an Hd scenario between 2050 and 2100 (180 days).

This research concludes is that from the inland shipping perspective there are two overarching considerations in the decision on canalization of the River Waal, the perspective of the navigability of the river and the perspective of its capacity to allow cargo transport. The navigability, described in (low) discharges and water depth, deteriorates due to climate change. Clear thresholds as TEN-T and CCNR requirements are not met and there is not sufficient water depth to accommodate the normative vessel CEMT VI+ year round. Taking action in the form of canalization would guarantee these requirements to be met now and in the future. Uncertainty in climate conditions causes that no clear predictions can be given on how severe the impact on the transport function is. Furthermore the transport function is more complex, since it describes a spread of individual vessels, different cargo types and a corridor. It is not inconceivable that adjustments within the 'transport function', like alterations in the logistical chain or improvement of the fleet, could (partially) counteract the negative impacts of climate change, which subvert the necessity of canalization. Apart from that, this research concluded that for the transport function there are no uniform quantified goals. Goals mentioned are the added value to Dutch GDP, the role in other sectors, the model shift and (military) strategic. Since these goals are broadly formulated, but not well quantified, it is difficult to identify limits in the performance of the system under climate change which could argue the necessity of canalization. To make a deliberate decision on canalization based on its capacity to allow cargo transport, it should first be defined and quantified what achievements should be made with the River Waal.
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The Netherlands faces major housing shortages. The total housing shortage is 390 thousand homes and this is expected to increase in the near future because fewer building permits have been issued in recent years. By 2030, the Netherlands will need to have almost a million new houses. To solve this problem, it is essential to build more residential buildings in the near future, but limited space is available. Therefore, the focus shifts to traditionally less conventional spots that potentially can be used to construct residential areas.

One of the proposed solutions is to create residential buildings near dikes, thereby using the dikes not only to combat flood risks but also to relieve pressure on the housing crisis in the Netherlands. To check if buildings can be built on or next to a dike, the assessment method of the Legal Assessment Instrumentation is currently used. However, only a basic assessment is prescribed for this, which is a very conservative approach. This conservative approach often leads to the building not being built or to overdesigning of the dike and thus higher expenses than necessary.

The objective of this thesis is to develop a level I reliability assessment method for multifunctional dikes containing a structure, leading to a less conservative approach than the basic assessment of the Legal Assessment Instrumentation (WBI2017).

First, the possibilities of construction near dikes were studied per water board. The possibilities for building near dikes are prescribed in the water board regulations, previously known as the by-law (Keur). Although the water board regulations vary for each water board, the rules regarding building near dikes are consistent, and almost nothing regarding construction can be done in the profile of free space. Interviews were also held with water boards. During these interviews, the regulations were discussed, including the non-technical obstacles with regards to building near dikes and solutions for them were proposed.

The biggest concern is regarding the management of the houses that would be part of the flood defence. One of the proposed solutions is to use people to regularly send photos to ensure the quality of the parts of the house that will function as flood defence or to use sensors which could measure deformations. This could save much time for the dike managers.

Next, it was determined what failure mechanisms can be affected by the presence of a building on or near a dike. The failure probabilities of macro-stability, piping and overtopping differ when a building is placed on or next to a dike and have been considered in the calculation of the failure probability of the dike. It has been argued by means of an event tree that the absence of a house has a 0.1% probability of occurring.

Subsequently, a case was analysed probabilistically using FORM analyses to demonstrate the difference in failure probability between the current and the proposed schematisation. This showed a 75% reduction in failure probability for the assumed cross-section compared to the current schematisation. The effect of new construction on a standard dike profile can both have positive and negative effects on the failure probability of the dike section depending on the situation. Compensatory measures can be taken to reduce the probability of failure.

Since it is time-consuming to perform probabilistic calculations for every situation, it was decided to create a Level I reliability assessment. Based on the probabilistic calculations, partial safety factors were derived that take the probability of the disappearance of a house into account. These partial factors were calculated per stochastic variable. This allows for a Level I reliability calculation to determine whether a dike cross-section with a house meets the required failure probability of the dike section.

It is concluded that incorporating the proposed level I calculation with adapted partial factors has a different impact for each situation but can, in some cases, have a 75% reduction in failure probability. This is based on the case study, which is elaborated extensively in the report. The developed level I reliability method ensures that existing buildings near houses are assessed more realistically compared to the current WBI assessment, which assumes a gap at the location of the dike. As a result, when this method is used, more dike cross-sections with buildings will meet stability requirements as it is less conservative than the current assessment, which only takes into account the negative aspects of the building. This means that fewer dike sections will be rejected, potentially saving both money and reducing inconveniences. For the design of new structures near a dike, this Level I reliability calculation can provide insight into possible locations for construction in the cross-section of the dike and the potential dimensions of the house. With this method it can quickly be demonstrated whether a multifunctional dike still meets the dike's failure probability requirement, which can also lead to an increase in building possibilities near dikes, as extensive customized assessments are no longer necessary. ... Read more

The research, "An Integrated Approach to Identify Sustainable Materials and Strategies to Achieve a Carbon-Neutral Breakwater Design," aims to design breakwaters that maintain structural integrity and functional performance while minimizing environmental impact. The research addresses the urgent need to reduce carbon emissions in coastal engineering, aligning with global climate change mitigation goals.
The primary objective is to develop a comprehensive framework for designing carbon-neutral breakwaters... ... Read more

Safety assessments are taken every five years to examine whether the coast is safe enough. After investigation, it was found that one of the weak spots is the Hondsbossche and Pettemer Sea defence (from hereafter referred to as HPZ) which required reinforcement at this location. Therefore, a mega nourishment was implemented in 2015 to ensure the safety of the hinterland. The implementation of this mega nourishment created the Hondsbossche Dunes (from hereafter referred to as HD). After the implementation of the mega nourishment, it was soon found that the width of the beach decreased. The beach width is defined as the horizontal distance between the waterline and the dune foot position which is defined at elevation NAP + 3.0 m. The decrease in beach width occurred mainly on the edges where there is a stronger curvature, so more change in shoreline orientation, compared to the other parts of the nourishment. As a result of the decrease in beach width, an additional nourishment was implemented in 2018 to meet the requirements. These are not the safety requirements but the beach width is important for recreation so the beach cannot be too narrow.

The aim of this research is to improve understanding of beach width reducing processes at curved coastlines to improve predictions of beach width on a scale of ~5 years after implementing a nourishment at the HD. The relationship between the curved coastline and long waves and its influence on the change in beach width was investigated. Special attention is given to the role of infragravity waves. Hereto the numerical model XBeach is used which can simulate morphodynamics with and without infragravity forcing. From the literature review, it follows that long waves, also called infragravity waves, are formed from small waves. A difference between infragravity waves and short waves is that the processes of the infragravity waves take place mainly in the surf zone and swash zone, while most of the short waves are dissipated in the surf zone and swash zone.

To determine the influence of coastline curvature and infragravity waves on beach width change, two types of models were run. The first model was a schematic model where an alongshore uniform coast is applied in the model to neglect the influence of alongshore variability in cross-shore profiles. In addition, multiple runs were performed varying the strength of the curvature and the mode (stationary mode, so without infragravity waves and groupiness, or surfbeat with infragravity waves) so that the results could be compared. This study showed that including infragravity waves results in a different predicted beach width change. In addition, stronger curvature leads to larger gradients in longshore sediment transport and thus the change in beach width.

The second model run was the HD’s complex model where the conditions as present in reality were applied, i.e., bathymetry and wave conditions. Based on the XBeach model of the HD, it can be concluded that the prediction is reasonably similar for the first year of the simulation. The first year of the simulation is the second year after the nourishment is implemented, i.e. 2016, so initial effects are not included in the result of the measurements. However, the predictions and measurements hardly match in the other years resulting in a very low correlation which follows from the validation. ... Read more

In the center of Amsterdam there are historic quay walls that are more than 100 years old. Over the years, the load-bearing capacity of the quay walls decreased, and it is currently an important topic on how to strengthen these quay walls, but it is important as well to know which quay walls should be given preference for rehabilitation.

The engineering department of the municipality of Amsterdam, in collaboration with other parties, has drawn up a document Toetskader Amsterdamse Kademuren (TAK 3.2), which includes various aspects that contribute to the assessment of historic quay walls. In TAK 3.2, attention has of course been paid to the geotechnical aspects, whereby material model parameters have been determined for the Hardening Soil small strain model and the Soft Soil model. This study examines how the current parameter set in TAK 3.2 can be improved by selection of material model parameters and taking the material models into consideration as well in which the anisotropic Sekiguchi-Ohta model and the anisotropic S-Clay1 model are examined additionally.

Material model parameter sets have been compiled (with expected values) for the most influencing Holocene soil layers, such as Geulopvulling, Hollandveen and Oude zeeklei. These parameter sets have been validated and further optimized with the use of Plaxis SoilTest. The available laboratory results come from isotropically consolidated triaxial tests on Geulopvulling and Oude zeeklei, Direct simple shear (DSS) tests on Hollandveen and oedometer tests. Validation of the anisotropic models has therefore not been entirely possible for Geulopvulling and Oude zeeklei, but in the case of Hollandveen the assumption is made on K0-consolidation in the DSS test simulations, where the anisotropic models yield promising results.

Furthermore, according to the approach of TAK 3.2 in the staged construction of historic quay walls, various simulations are conducted for the assessment of historical quay walls with the Hardening Soil small strain model, Soft Soil model and S-Clay1 model, with different parameter sets. From these simulations, some good prospects are noted, such as the improvement in output results with the optimized parameter set compared to the parameter sets gathered from all laboratory data and TAK 3.2. In simulations in which the S-Clay1 model is considered in combination with the Hardening Soil small strain model and Soft Soil model, a significant decrease was noticed as well in the output results compared to simulations with exclusively the Hardening Soil small strain and/or Soft Soil model.

This study shows that the Hardening Soil small strain model as an isotropic model gives better results and fewer/no difficulties in the finite element method calculations compared to the Soft Soil model. It is further confirmed that calculating the initial phase with the K0-procedure with horizontal soil layers and surface is the best method in the case of the assessment of historic quay walls.

By understanding which differences are observed with different material models and parameter sets, this study contributes to sharpening future research to adequately analyze and assess historic quay walls in the center of Amsterdam. ... Read more

In the Netherlands, there are hundreds of operational locks for both recreational and inland shipping. Due to the growing economy, inland shipping is expected to increase in the future. The growing economy causes an increased likelihood of ship collisions with infrastructure, currently estimated at approximately 50 cases per year in the Netherlands. It is necessary to determine the collision energy of a vessel to account for collisions, because this clarifies the potential load. In the context of determining the collision energy for ship collision, the guidelines of the Eurocode, PIANC, and AASHTO involve uncertainties and exhibit variability among them. Therefore, the thesis was initiated to provide more accuracy in the estimation of collision energy in the event of ship-lock collisions. The main objective of this thesis was to enhance the structural design process of lock gates regarding ship-lock collisions. This was done by improving the understanding of the effect of potential loads occurring at a ship-lock collision, and using basic mechanics to estimate the energy absorption capacity of the lock gate. ... Read more

The surge in demand for inland vessel goods transportation has necessitated the operation of larger vessels with increased drafts. These larger vessels generate significant induced loads from their more powerful bow thrusters during berthing and mooring. These loads can lead to scour, which ultimately results in instability of the quay wall. To counteract this, stone gradings are penetrated with colloidal concrete as bottom protection. However, prior studies indicate that the flow velocity profile perpendicular to a quay wall decreases more rapidly than guidelines suggest, implying a potential reduction in the extent of colloidal concrete application. This is relevant for the Netherlands, where a multitude of hydraulic structures, including an estimated 130 locks, are in need of renovation or replacement. \\

\noindent This study seeks to comprehend the impact of bow thruster-induced loads directly perpendicular to the quay wall, on stone displacement near a quay wall and this study compares the outcomes of this field measurement with existing guidelines and scale modelling. The research question is therefore: ''\textit{How can results from a full-scale test improve the design and performance of loose-rock bottom protection against bow thruster-induced loads for quay walls accommodating inland vessels?}''\\

\noindent In order to answer this question a full-scale field measurement is conducted with the largest inland vessel in Europe. During this field measurement, free flow tests were performed and bottom velocity, pressure fluctuations and stone displacement were determined. \\

\noindent The applied bow thruster power and under keel clearance are marked as two important parameters for stone displacement. For the impact of this applied bow thruster power and under keel clearance, a variety of scenarios is examined. After each scenario a survey is done to look at individual stone displacement. Velocity measurements are taken to get more information about the flow velocities. The velocities were measured relatively far away from the bottom, resulting in low velocities. The actual bottom velocity is determined by validating and using the findings of the scale modelling performed by \textcites{Deltares}.\\

\noindent Free flow tests are performed to directly measure the outflow velocity and compare it with existing guidelines. From these tests, it is concluded that the existing guidelines for outflow velocity result in an overestimation of the required $d_{n50}$, with a measured loss coefficient of 0.65 as opposed to the proposed 0.90. Even with the reduced loss factor for the outflow velocity, the bottom velocity calculated with the Dutch method guideline is higher compared to the actual bottom velocities, demonstrating again, as already indicated in prior studies, that the guidelines are too conservative. \\

\noindent The turbulence intensity values play a significant role in validating the findings derived from scale modelling conducted by Deltares. The measured turbulent intensity values show similarities with the earlier findings, indicating a turbulent environment and validation of the Deltares scale modelling. \\

\noindent Based on pressure measurements, it is estimated that at the onset of movement, the pressure differences of the turbulent eddies are in the order of 50 to 90\% of the critical force to cause stone movement. \\

\noindent The in this study developed parameter R = $\frac{V_0}{UKC} \cdot t \cdot \frac{1}{k_{sl}} \cdot C_R $ shows that an increase in applied bow thruster power, a decrease in under keel clearance, an increase in duration and in slope lead to a linear relation with the normalised cross-section area of the near-quay erosion hole. \\

\noindent In addition, the full-scale field measurement showed that the stone displacement predominantly occurs within the first two and a half meters of the bottom protection, suggesting a possible reduction in the width of the colloidal concrete application. For a fictive quay wall the suggested reduction is compared with the design following the original guidelines. The suggested reduction alternative could save 75\% of the amount of colloidal concrete and CO$_2$ emissions. ... Read more

This design report outlines a preliminary masterplan for developing a sustainable village in Patagonia, Argentina, addressing the unique challenges of remote living within a sensitive natural landscape. The project centres on creating a resilient, socially sustainable community that coexists harmoniously with its environment. A key objective is to assess multiple sustainable options for essential infrastructure, encompassing energy supply, accessibility, water and wastewater management, and other critical systems.
The report begins with an exploration of the site’s distinctive environmental conditions, informed by a two-week site visit, as well as an analysis of key stakeholders, including residents, tourists, and potential investors. This groundwork establishes both community needs and environmental constraints, forming the guiding principles for the design. The preliminary masterplan then proposes practical solutions to meet these requirements, including infrastructure development such as jetties for enhanced accessibility, a hybrid renewable energy system to support off-grid living, and water and waste management systems that minimise ecological impact.
The proposed design is evaluated for economic feasibility, ensuring the village can support sustainable eco-tourism and community growth over the long term. This project could be used as an example for future developments in rural areas by prioritising sustainability for all social, environmental and economic aspects. This preliminary masterplan aims to contribute to ongoing research on environmentally conscious and socially inclusive development in challenging environments. ... Read more

This report addresses the design of a quay wall on a steel slag subsoil. The reason for this study is the realisation of a wind turbine assembly port. Worldwide hydraulic structures are seldom made in these artificial soils. This steel slag material present in the project area complicates the construction of a quay. Is it possible to install foundation piles in this material? What environmental aspects need to be taken into consideration? Which quay wall type is most suitable for realising the port area?
The study starts by explaining the motivation behind the quay wall structure on this unconventional soil. The main reason for the need for wind assembly ports is to increase the wind turbine installation and maintenance capacity. The problem analysis explores the challenges associated with the steel slag materials, this leads to the problem statement and design objective. The problem can be summarised as follows: Despite the large experience in port developments and quay wall constructions, the ability to efficiently design a quay wall on a varying soil system like steel slag, is still considered complex. This leads to the goal of this thesis, which is to create a conceptual design of a quay wall on a steel slag subsoil at the location.
The design analysis aims to find the most efficient quay wall design, which is possible to construct and even take advantage of the presence of steel slag material to increase structural performance and stability. In the thesis approach, the steps taken to achieve the goals of the study are shown. The report proceeds with the development of a method in which the different characteristics of the steel slag material are examined.
The steel slag materials have some positive and negative effects compared to regular soils. The relatively high friction angle and high density can benefit the structure when applied at the right location.
One of the issues with using steel slag is the risk of environmental implications. When steel slags come in contact with air and water, heavy metals can leak out of the slag causing damage to the ecosystems and humans. The design solution aims to mitigate the environmental risks without exponentially increasing the costs.
A system analysis follows including an area, stakeholder and function analysis. This helped to illustrate the broader environment and requirements for the quay wall construction. The basis of design section outlines the starting points and boundary conditions whereafter the programme of requirements and evaluation criteria are defined. The report includes a functional and structural design.
After analysing potential alternatives for constructing a quay wall, the cofferdam variant was the most promising given the required bearing capacity, height and subsoil. The cofferdam design consists of two combi walls connected with tie rods at two levels. For stability, a grout anchor is connected to the backside of the combi wall. A low permeable environment was created because a clay layer is present between the two walls. The cofferdam dimensions were chosen so that most of the steel slag material would be enclosed between the combined walls. The residual volume of steel slag material is used as a fill material for the piles.
In the structural design, a detailed construction sequence and the design model were provided.
A PLAXIS 2D model based on Finite Element Method (FEM), was made for two cross-sections of the quay wall. Based on the outcome, the elements of the quay wall were verified and optimised. The installation method of the combi wall has a large impact on the cost. Results were analysed and risk-mitigation measures have been advised to provide a controlled construction. Various checks on stability, strength, stiffness and deformation were conducted to ensure this design meets the technical standards.
The validation of the design was then performed to check whether the design objective was adequately formulated and correctly translated into the requirements. As the client was Port of Amsterdam, the design was validated in correspondence with this company.
The report concludes with a discussion of design considerations and the implications of the design choices. Finally, the conclusions and recommendations section summarises the key outcomes of this report.
Based on the outcome of this report, it can be concluded that the construction of a safe and stable quay wall is possible with the right construction measures. It was recommended that further analysis of the environmental impact of the re-usage of steel slag material be conducted.

For further research, it was recommended to perform detailed calculations on the connection between the elements. In addition, a hydrological test could be performed to understand the flows of the rain and groundwater in this design. For the execution of the structure, it was recommended to perform an additional pile driving test with the driving shoes to prevent failure. The test results will show it this setup is suitable for the realisation of the quay wall. Additionally, it can provide extra certainty on the construction time, cost and knowledge. ... Read more