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.

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.

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.

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...

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.

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.

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.

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.

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.

The Noordtunnel is an immersed tunnel open to roadway service since 1990 in The Netherlands. Over the past thirty years of its operation time, a significant differential settlement behaviour has been observed, and this ongoing settlement potentially imposes safety concerns to the tunnel, such as joint leakage. However, the underlying factor triggering this differential settlement behavior remains unknown. To ensure the tunnel's serviceability, this thesis aims to investigate the underlying causes of the occurring excessive settlement, predict future settlements, and assess its impact on tunnel structural safety within its designed lifetime.

The analysis starts by reconstructing the settlement time history of the Noordtunnel. The process involves determining the most reliable reference point and performing back analysis to estimate the settlement magnitude during the unmeasured period. Further, the settlement history is reconstructed by combining all the settlement data of all the periods. It is found that the settlement history at all immersion joints show a logarithmic trendline, with a maximum estimated settlement of about 94.36 mm occurring at immersion joint 2. Subsequently, the soil profile and geotechnical parameters were determined for the simulation. The provided Cone Penetration Test (CPT)s data and borehole ensure the soil profile depicted in the given situation map. Additionally, in the absence of laboratory data, the Hardening Soil Model (HS Model) and Soft Soil Creep Model (SSC) parameters are estimated based on CPT - NEN Table 2b correlations.

Afterward, the Two Dimensions (2D) Finite Element Method (FEM) simulations were carried out in PLAXIS (a commercial simulation software), while considering the variations of load acting on top of the subsoil. Two types of soil constitutive law were chosen to simulate the settlement in the Noordtunnel: HS Model and SSC Model. The optimum model, which can simulate the settlement behaviour in the field, was selected by aligning the simulation outcomes to the reconstructed historical settlement. The simulation results show that only settlement at immersion joint 2 has the same tendency as the SSC Model, while the other immersion joints tend to have a similar tendency to the HS Model. The simulation outcomes also indicate that excessive settlement at immersion joint 2 occurs due to the soft soil underneath the tunnel and the natural sedimentation on top of it. The soft soil is responsible for at least 20 mm of settlement, while the sedimentation contributes to a minimum of 8 mm of settlement during 30 years of tunnel operation. Subsequently, the sensitivity analysis is conducted to examine how much the simulation outcomes may deviate when accounting for soil variability in the field. Due to the narrow distribution of the reference values, adjusting the most sensitive parameter will only deviate the results by a maximum of 5.48% at immersion joint 2 and 4% at the other immersion joints. These results indicate that the model is robust enough and expected to generate reasonable future settlement predictions. An additional settlement of 15.13 mm of settlement is predicted to occur at immersion joint 2, while 4 to 5 mm of additional settlement is anticipated at the other immersion joints over the tunnel's remaining lifespan.

The differential settlement at the tunnel longitudinal direction has triggered element tilting and further induced compression and decompression to the GINA gasket at immersion joints. It has been observed that while uneven settlement contributes to joint decompression, the external forces acting on the GINA gasket remain considerably lower in magnitude compared to the overall friction force. Therefore, the impact of uneven settlement on the water tightness is generally minimal. Additionally, considering the limitations of the current monitoring procedure, an optimized monitoring plan based on the Distributed Optical Fiber Sensor (DOFS) system is proposed. Finally, future recommendations to improve the current thesis are also put forward.

The Dutch Rhine-Meuse delta is expected to require many dike reinforcements on a short and long term, due to (accelerated) sea level rise. Average damage in unembanked areas will increase too, and a costly replacement of the Maeslantkering is expected after 2070. Delta21 is a project that aims to address these challenges related to flood protection, while also providing hydraulic energy storage and opportunities for valuable nature development.
Delta21 consists primarily of a large (salt)water storage lake attached to the Tweede Maasvlakte. It is connected to the North Sea with a pump-turbine station. On the southern side, a closable storm surge barrier spans the remaining gap to the island of Goeree Overflakkee. Under normal circumstances the lake functions as a hydraulic battery, using the pumps and turbines to store or generate electricity as needed. However, when water levels threaten to exceed NAP + 2.5 m at Dordrecht, the barrier closes and an upstream spillway into the lake is opened. To determine the viability of the project in the context of flood protection, the question arises: “To what extent is Delta21 capable of providing a cost-effective alternative to the current flood protection policy in the Rhine-Meuse delta?”
To answer this question, a one-dimensional hydraulic model is constructed with a detailed and accurate schemati-zation of Delta21. Results are processed into exceedance frequencies for a system with and without Delta21, to obtain reductions in water levels at normative frequencies. Furthermore, a sensitivity analysis is performed to de-scribe how various designs and configurations affect the magnitude of these reductions. Other than Delta21, no system-changing interventions are included in the scope of study.
Three strategies are formulated in which Delta21 potentially reduces costs, and evaluated using the model’s results:
1 Extending the lifetime of the Europoortkering before it needs to be replaced.
2 Obviate dike reinforcements.
3 Reduce the average yearly damage of unembanked areas.
Approach 1 is shown to be ineffective. Delta21 does not achieve changes in the Europoortkering’s closure frequency or failure probability per closure. Neither does Delta21 effectively mitigate a failure in the region where water level exceedance frequencies are dominated by the Europoortkering’s failure probability.
Approach 2 is far more successful, accounting for 96% of the total cost reductions. Reductions in water levels at normative frequencies are translated to reduced failure probabilities of dike segments using fragility curves, which potentially yields a positive reassessment. Delta21 achieves this and obviates dike reinforcement for 41 km by 2050, and 150 km more by 2100. These lengths comprise respectively 33% and 60% of the total considered dike lengths that would need reinforcement. The net present value of obviated reinforcement costs is €752 million, with a 90% confidence interval of [€220 million, €2,821 million]. This large interval is due to large uncertainties in reinforcement cost estimations. Delta21 most effectively obviates reinforcements in trajectories with stricter norms and closer proximity to the storage dominated region. Water levels at normative frequencies are very sensitive to the opera-tional control (i.e. closure criterion) of Delta21. An additional nominal cost reduction of ca. €278 million can be achieved when a criterion of NAP + 2.5 m at Dordrecht is maintained in the future. The sensitivity is far weaker to varying dimensions or capacities of Delta21, which are generally unnecessarily large during illustrative conditions.
Approach 3 provides the additional 4% contribution to total cost reductions. The only considered area is Dordrecht, due to its unique high economic value in low lying unembanked locations. Damage profiles are integrated with changes exceedance frequency curves to obtain the average yearly damage. This is reduced by approximately €53,000 per year now, and grows to €1.36 million per year in the future climate scenario (2100). The decrease in relation to the current system is about 42%, but the absolute value rises greatly with sea level rise. Implementation of lower closure criteria variations can yield an additional +20% now, and +10% in the future scenario.
The total net present value of cost-reductions by Delta21 is €783 million, with a 90% confidence interval of [€251 million, €2,852 million]. This covers about 20% of the total construction costs of €3.7 billion, and is insufficient to make Delta21 viable alone. However, not all costs are related to flood protection exclusively. If the components required for energy storage are viable on their own, merely the additional costs of the spillway and storm surge barrier have to be included in the cost-benefit analysis. Operational costs, which heavily depend on the operational control, must also be added. Smaller design dimensions or pump capacity of Delta21 has been shown to be just as effective, and would further cut costs. Additional savings beyond 2100 are plausible, but outside of this research’s scope. Furthermore, less people displacement or flooding of unembanked areas may achieve additional societal value, but is difficult to quantify. More research will have to indicate whether attributing only specific costs, including additional value sources, and estimating reinforcement cost more accurately ultimately lead to Delta21 being fea-sible in the context of flood protection.

If sea level rises faster than anticipated in the initial design of rubble mound breakwaters, a serious threat is posed to their functionality. To limit wave overtopping, breakwaters must be adapted to the rising sea level and subsequent increase in wave loading due to reduced depth-induced wave breaking. However, the projections of sea level rise are highly uncertain. To deal with this uncertainty and avoid unnecessary costs, the method of adaptation pathways can be applied.

The thesis aims to incorporate changes in depth-induced breaking uncertainty of sea level rise in the creation and selection of adaptation pathways for rubble mound breakwaters.

As a first step to reach the objective, methods are proposed based on existing concepts from literature, modified to be applicable to adaptation pathways for breakwaters.
To consider changes in depth-induced breaking when determining wave loading on breakwaters, two empirical estimates are proposed. The maximum significant wave height at the toe of the breakwater is assumed equal to half the water depth at the toe. The spectral period at the toe is assumed to be equal to the deep-water spectral period for shallow foreshores.
To account for sea level rise uncertainty in the selection of pathways based on cost, methods for model uncertainty and for scenario uncertainty are proposed. The first method uses an approximated probability based on model uncertainty to estimate the expected cost of the adaptation pathway. The second method deals with scenario uncertainty by computing the weighted average of the cost of pathways for all considered scenarios.

The applicability of the proposed methods is tested on a case study for the location of IJmuiden (the Netherlands). For the case study, five adaptation measures are considered: placing a low-crested structure, adding a berm, raising the foreshore bed, adding a crest wall, and raising the armour crest level. The last three mainly form the optimal pathways in the case study.

Lastly, the empirical estimates and formulae used to create adaptation pathways are validated with an XBeach model and an OpenFOAM model. The estimates of the significant wave height and spectral period have a maximum deviation of 21% and 15%, respectively, compared to the numerical results. Moreover, the comparison with the numerical model indicates that the overtopping expressions of Van Gent et al. (2022) can predict overtopping results with reasonable accuracy, even for conditions which fall outside the range of validity.

Based on the case study it is concluded that the method to incorporate sea level rise uncertainty in the selection of optimal pathways gives insight into the preferred measures and the likelihood of measures being applied in the lifetime of the structure. The results of the case study also indicate that the preferred pathways do not vary between different sea level rise scenarios. Based on the numerical validation it is concluded that the method to incorporate depth-induced breaking in adaptation pathways can be used as a first estimate but more detailed calculation methods such as numerical models are necessary to accurately create adaptation pathways.