Amsterdam and many other cities consist of a network of old quay walls, which sometimes have been constructed over a century ago. A large uncertainty exists concerning the current safety of these quay walls and their remaining service lifetime. In the current framework for the assessment of old urban quay walls, the influence of timber creep in the structure is being omitted. It had been expected that a part of the excessive deformations occurred are part of this timber creep as opposed to progressive failure. Hence, this research studied the influence of wood creep on the structural behaviour of old urban quay walls, using a case study based on the Herengracht. For the modelling of the quay walls, use has been made of the Embedded Beam Row (EBR) elements in Plaxis 2D. As this element type has no material model which takes into account creep, use has been made of pseudo-elasticity. The behaviour over time had been modelled by reducing the elastic stiffness of the EBR elements with increasing creep factors. To force Plaxis to perform calculations, this stiffness reduction has been introduced as a reduced strength in the form of a custom moment-curvature diagram. At the time of writing, the Embedded Beam Row had not yet been validated for cohesive soils. Hence, a verification has been executed of the EBR using a full-scale load test performed on a pile group in Salt Lake City. In this case, a 3x5 pile group driven in multi-layered cohesive and non-cohesive soils had been laterally loaded. The results included deformations, total horizontal load and bending moment distributions over depth. It has been found that the EBR provides reasonable results when modelling laterally loaded pile groups. The force-displacement curve from the field test was only slightly stiffer compared to those obtained using Plaxis 2D. Maximum bending moments obtained using the EBR had been found to be 20 to 30% compared to the experimental data. The group efficiency of the pile group was initially lower for small displacements, which was likely caused by the lack of installation effects of driven piles in the Plaxis model. It has been observed that the Interface Stiffness Factors (ISF) that are used to calibrate the EBR behaviour have a limited range. Increasing the ISF values beyond a certain limit will no longer affect results, as the interface connecting the EBR to the soil will have become practically rigid at this point. Nevertheless, it has been concluded the EBR can be used in this case to model laterally loaded pile groups. The influence of the timber creep on the structural behaviour of quay walls has been studied using a model based on the Herengracht in Amsterdam. A maximum creep factor has been applied of Φ=1.6. Two methods have been used to apply the final creep factor. With the "Direct" method, the maximum creep factor was applied in the same phase as the load. With the "Indirect" method, the creep factor has been applied incrementally in steps of 0.1. It has been observed that the results from these methods deviate significantly. With the Indirect method, larger creep displacements have been calculated, as well as lower maximum compressive stresses in the piles. The creep behaviour has been studied in more depth using the Indirect method. In this case study, creep displacements of 2.22 times the initial displacement have been calculated. When plotted against the increasing creep factors, it has been observed a power function could be fitted to the data. In addition, a stress reduction of 0.590 times the initial maximum compressive stress has been observed in the front two pile rows. This stress reduction was achieved at φ=0.4. In the most landinwards pile row, stresses continued to decrease, with a reduced rate beyond φ=0.4. A sensitivity analysis has been performed to study which parameters have significant influence on the creep behaviour. Conclusions were drawn based on the relative change in horizontal displacement and maximum compressive stress in the front pile row. It has been concluded that the shear strength parameters of the top layer, the elastic modulus of the timber, surface load and the geometry have the largest influence on the creep behaviour. Furthermore, it has been discovered that the size of the creep factor steps influences the final stress and displacement. With decreasing stepsize, convergence occurred in the results. From the results it has been concluded that the structural behaviour of old urban quay walls is significantly influenced by timber creep. The inclusion of timber creep resulted in large displacement increases, but also in stress reduction. The results suggest that excessive deformations of quay walls does not mean that an ultimate limit state has been reached. It is recommended to include the timber creep in the modelling and assessment of existing quay walls.

Crossing waterways is crucial to improve transport connections. In particular, new crossing methods are needed when the distance to be covered increases. Submerged Floating Tunnels (SFT) have been recently emerging as a cost-effective feasible crossing technique to connect fjords in Norway. However, only very little research has addressed the vehicle-structure interaction, with attention to the passengers, so far. In the current thesis, an algorithm was developed to study the Fluid-Structure-Vehicle-Interaction (FSVI), where the tunnel has been modelled as a Euler Bernoulli beam, the train car as a 6DOFs system, the supporting cables as linear springs, and the fluid by the Morison's hydrodynamic force expression. The Sperling ride quality and comfort indices were used to address human comfort while crossing the tunnel. It is found that, due to the low-frequency hydrodynamic environment, the influence of the FSVI on the Sperling's indices is limited, i.e. "just noticeable" from the classification table. Low-frequency flow field may cause motion sickness rather than cause comfort/discomfort during the ride. The illness rating, which is the indicator of the motion sickness, gave positive outcomes due to the small amplitude of the accelerations, and therefore no illness is expected to be felt by passengers. This study shows that displacement and acceleration can be controlled and kept inside the proposed boundaries under storm sea states, and the comfort while crossing can be guaranteed. The approach here used can be applied to other sea states with higher frequency content to address the comfort in a storm with smaller return period, which may also be important to address the fatigue resistance of the structure.

This study presents the results of small scale flume experiments on a submerged rectangular cylinder subjected to a current, regular wave and combined wave-current environment. The objective of the study is to gain more knowledge about the hydrodynamics around and the kinematics of a submerged structure, to give a contribute to the research field of the submerged floating tunnel. For this study a rectangular cylinder with an aspect ratio (breadth-depth) of 2.5 is used. Two relative submergence depths (flume depth/model submergence) of 2.75 and 1.63 are tested. For all tests a still water depth of 0.7 m is applied. Waves resulting in very low KC numbers of <1 for regular waves and KC[1+U_c/U_m ]<2 for combined waves-current are generated. To create a combined wave-current environment, a current is created in the flume, to which waves are added by the wave generator. The water velocity is measured in front of the model. To approximate the water velocity at the model, a time/phase shift is added to the velocity signal. Linear wave theory is applied to approximate the amplitudes of the orbital velocities at the depth of the model. For the first part of the study, on the hydrodynamic forces, the cylinder is rigidly fixed in the flume. Due to the inertia dominance for low KC numbers, the relationship between the wave parameters and the hydrodynamic forces is well described by the relationship between the wave parameters and the water particle accelerations. The vertical hydrodynamic forces are found to be larger than the horizontal hydrodynamic forces. The force coefficients from this study are compared to coefficient found in previous studies. The drag coefficients for the only current tests agree well with the results from (Courchesne & Laneville, 1979), (Bearman & Trueman, 1972), (Nakaguchi, 1968) and (Venugopal, 2006). For the regular wave and combined wave-current conditions comparable results are found to those by Venugopal for a rectangular cylinder towed through a wave field (Venugopal, 2008). The drag coefficients in the present study show a similar trend in magnitude as in the study by Venugopal. However, the magnitudes have an opposite sign due to the velocity phase shift method applied in the present study. Nevertheless, the effect of this difference on the total force prediction is insignificant, because of inertia dominance. In general, the Morison equation predicts the measured horizontal force well for regular waves. Adding a current component to the waves results in a larger error between the computed Morison forces and the measured force. However, an increase in the magnitude of the added velocity does not lead to a significant increase of this error. The second part of the study focuses on the same cylinder, only not fixed but held in place by 4 tethers. For these tests a buoyancy to weight ratio of 1.5 is applied. The used tested angles between the tethers and the flume bottom are 30˚ and 70 ̊. The water depth, the wave types and model submergence depths are remained equal to the first part of the study. By comparing the kinematics found in three different configurations, a 30˚ tether angle combined with the largest submergence depth of ds=035 m are found to gives the smallest displacements and accelerations. To reduce the kinematics more, it is recommended to add vertical tethers to limit the vertical movement. In general, dynamic features are seen in the tethered model, influencing the magnitude of the kinematics. To predict the magnitude of the tether forces it is recommended to integrated these features in a structural dynamic model.

Over time, degradation processes might cause damage to pattern-placed revetments. Examples of such damages are missing elements, deformation, and the loss of joint filling. However, little is known about the exact consequences of those damages. Therefore, when damage is observed during an inspection, it is estimated based upon experience what the possible consequences are. If the consequences are misjudged, this will lead to inefficient maintenance. Better insight into the exact consequences of damages will expand the possibilities of how risk-based maintenance can be used to maintain revetments. Consequentially, maintenance interventions can be planned more efficiently, reducing the societal costs incurred due to inefficient maintenance. This study contributes to this topic by investigating whether it is possible to estimate the impact of damages on the stability and reliability of a revetment using a model. Within the study, first, damages are analyzed based upon a literature review. Next, data of old flume experiments with Basalton and basalt revetments are analyzed to study and quantify damages. This analysis focuses on the uplift of elements, deformation around the wave impact zone (S-profile), and washed-out joint filling. Then, a finite element model (FE-model) is created to simulate the wave impact on pattern-placed revetments. The main focus of the FE-model is to study the uncertainty due to structural changes, which are the damages. The damages quantified during the analysis of the flume experiments are also included in order to be able to assess damaged revetments. Finally, the study uses the FE-model within a sensitivity analysis to study the most important uncertain parameters. Based on the samples used in the sensitivity analysis, response surfaces are fitted to obtain a model that can predict the damage for any set of parameters. Finally, these models are demonstrated in a case study of a coastal dike near Den Helder. An increase of 10 – 100 times of the failure probability has been observed for small deformations, while for medium to large deformations, the failure probability increased by 1000 – 10000 times. For no joint filling or a missing element, the failure probability increased by 10 - 100 times. This study showed that it is possible to create a finite element model that can estimate the impact damage has on the stability and reliability of a pattern-placed revetment. The obtained results can be used within the daily practise as part of risk-based maintenance as the study provides a way to obtain a first indication of the impact of missing elements, deformation, and washed-out joint filling. Additionally, the developed methodology can be used to obtain the impact of other types of damage. Although Basalton is the primarily investigated type of top layer, analysis of the flume experiments showed that basalt revetments are subject to identical types of damage. Therefore, it is expected that the findings within this study can be applied to a broader range of top layer elements with similar characteristics to Basalton (e.g. basalt, C-Star, and Hydroblocks).

The historic inner-cities in The Netherlands are largely known for their iconic channels and their accompanying quay walls, of which a significant number were constructed over 100 years ago. Due to the limited available space in the sub-surface of the urban environment, a high number of utility lines (i.e. potable water pipes and sewer systems) are situated in the vicinity of these quay walls. In recent years, a number of quay wall collapses have occured in the inner-city of Amsterdam, some of which have been attributed to utility line leakages. However, research into the interaction between inner-city quay walls and utility lines is lacking. Thus, the aim of this report is to answer the following question: "How does utility line leakage relate to deformation and failure of Amsterdam's inner-city quay walls and when does this interaction become significant?". The interaction between utility lines and inner-city quay walls works in both ways, thus the research is split up accordingly. The effects of utility line leakages on quay wall displacement and failure were qualitative studied using a literature study. The effects of quay wall displacement on utility line leakages were quantitatively studied using an analytical model. In this model, the interaction between utility line and surrounding soil was represented using a beam on a Winkler foundation, i.e. a beam supported by a distributed spring. The stiffness of the spring was represented as bi-linear, resulting from the equilibrium bearing capacity of the soil. Quay wall displacements ranging from 20 up to 100 mm were applied to the most common types and outer diameters of utility lines found in the vicinity of quay walls. Utility line leakage is deemed to occur if a predetermined threshold is passed of either maximum angular deflection, maximum allowable bending moment or maximum allowable shear force, each resulting from the utility line displacement. Although the scope of the study is the inner-city of Amsterdam, the study can be used in other cities with inner-city quay walls, given the circumstances are similar. The literature study showed that quay wall displacement and failure due to utility line leakage follows from internal erosion processes. Two requirements have to be met for instigation of internal erosion: a local head difference between the water level in the channel and the groundwater level in the soil body behind the quay wall, and an open connection in the quay wall structure in the vicinity of the aforementioned local head difference, enabling the flow of soil via water. The rise of the groundwater level can be the result of a potable water pipe leakage, but can also follow from external factors like heavy rainfall. Three forms of open connections were appointed. The first is scour protection screen leakage, which can result in erosion underneath the structure. The second is quay wall floor leakage, which can result in both erosion underneath structure and erosion in the soil body behind the quay wall. The third is sewer leakage, which can result in erosion in the soil body behind the quay wall. In the latter, the aforementioned head difference is not required. This is because the direction of groundwater flow is not towards the channel, but towards the sewer leakage, given that the sewer pipe is located below the groundwater level. Erosion underneath the quay wall floor can result in quay wall displacement towards the channel, while erosion in the soil body behind the structure can result in the formation of a subsidence pit. Both erosion underneath- as well as behind the structure can result in (further) deformations of utility lines. The former through quay wall displacement towards the channel, resulting in local soil displacement in which said utility line is embedded in. The latter trough local loss of soil, resulting in a local reduction of support. Both have the potential to result in relative utility line displacements, which can result in leakages. This process is can be denoted as a positive feedback loop. Actual failure of the quay wall due to utility line leakage can come in the form of collapse of the quay wall towards the channel or collapse of the road on top of the structure in the formed subsidence pit. Due to the dependence on external factors, quay wall failure resulting from utility line leakage can be described as a second order effect. It was found that exceedance of the maximum allowable angular deflection of the utility line joints is most likely to result in leakages. Leakage due to exceedance of maximum allowable bending moment is relatively less likely but still significant, while leakage due to exceedance of maximum allowable shear force is unlikely. In all utility lines, a higher bending stiffness resulted in a lower susceptibility to leakage. If utility lines are deemed susceptible to leakage, it is advised that these are monitored intensely.

Although the concept of a submerged floating tunnel (SFT) originates from the early 1900s, the cross-section is always assumed to be circular or rectangular. In this research, it is investigated whether this assumption is valid. In order to find the optimal cross-section, the optimization process is split into two targets. The first targets aims for an optimization of material use considering the large hydrostatic water pressure. The second target guarantees a tensile force in the tethers that support the SFT, while keeping the buoyancy weight ratio (BWR) as close to 1.0 as possible. This is beneficial for both the tunnel tube and the tether system. The optimal cross-section considering the optimization of material use is an 'egg-shape' or an oval which deviates slightly from a circle. This is modelled by the form-finding process as executed in the Grasshopper software. This is due to the relative pressure difference between SFT-top and SFT-bottom. The ovalization decreases for increasing depth. The second target results in an ellipsoidal shape, with a flat bottom and convexly shaped top (in case the SFT is anchored to the seabed). This shape reduces the drag and turbulence on the SFT, while a lift force is generated contributing to the tensile force in the tethers. An analogy with an aeroplane wing is made. The magnitude of the lift and drag force is evaluated by solving for the Panel Method in Python. A significant reduction in drag and turbulence becomes visible. Moreover, some significant lift forces are generated by the encountering flow. The wave load must be compensated by the BWR to assure a tensile force in the tethers. All together, two types of solutions are presented. The ideal solution would be an inner (concrete) tube which absorbs the water pressure with a steel exoskeleton to reduce the drag and generate a lift force. The exoskeleton has a flat bottom and a convexly shaped top (when anchored to the seabed) A compromise between the targets is also possible and presented within the research. This compromise also has a flatter bottom and a more convexly shaped top, but still has some appearances of a circle.

Due to often existing subsea infrastructure or challenging seabed conditions, engineers are forced to design newnearshore pipeline trajectories that are not always in a straight line. Since subsea tie-in operations are often complex and relatively expensive, alternative methods like pulling pipelines into a curve are worthwhile. By means of this research fundamental knowledge of pipe pull operations into curved trajectories is acquired. This thesis research focuses on the soil - structure interaction between the sliding pipeline and the seabed. A more thorough understanding is obtained of the geotechnical processes that create lateral resistance of the pipeline against the forces applied by the installation vessel. The main goal behind this thesis is to expand the capabilities of pipeline installation by exploring the feasibility of curved pipe pull projects. The research is based on three fundamental elements: 1. An extensive theoretical study 2. A validated numerical soil-structure interaction model 3. A successful physical test campaign of thirty-two experiments The theoretical study of the thesis focuses on the physical processes that play a role during curved pipe pull operations. Research is conducted to gather knowledge of the three main subjects of research, being: 1. Structural behaviour of a concrete covered pipeline 2. Geotechnical behaviour of soil under lateral pipeline displacement 3. Geotechnical behaviour of soil under axial pipeline displacement Since this was the first known research into curved pipe pull operations, influences of dynamic environmental loads are excluded from the scope of research. The second stage of the research focused on creating an engineering model that enabled to predict to what extend partially embedded pipelines can be pulled into a curved trajectory on sandy seabeds. After considering multiple simpler structural models, the final result was a non-linear spring supported tensioned bending beam model. Within this computational prediction model: the lateral soil resistance is modeled by means of a P(Y) spring model, while the pipeline is represented by the tensioned bending beam. The applied lateral soil resistance model is computed based on researches ofWang et al. (2018) and Verley and Sotberg (1994). After themodel was completed, a purpose made test facility was created to pull scaled pipelines into a curved trajectory. During the test-campaign, five different model pipelines were tested on a scale range of 1/11.8 to 1/5.3. The physical test campaign provided valuable experimental data of thirty-two successful drained curved pipe pull tests. By means of the acquired set of experimental data the model was able to be validated. Since the model pipelines differed in diameter, specific weight and bending stiffness, the influence of those parameters is examined. From the fact that the majority of the model pipelines was pulled into a radius that was 0-30% lower than the computed radius,we can state that the numerical model predictions gives awell defined upper limit of the controlled pull radius of pipelines. Along the classified critical curved pulls, the imposed lateral force during the experimentswas within 20% of the maximum predicted force in 86% of the physical tests. From this observation we can conclude that the numerical model captures the maximum lateral pull force with a high accuracy.

At the Shonai River around Nagoya, Japan, several flood related problems occur. These problems occur at different locations, each with its own problems or limitations. The desired safety level as requested by the government is that the river should be able to have a discharge which has a probability of failure of once in 200 years. At many locations, the current probability of failure is lower than once in 50 years. This has led to the following research question: How can the discharge capacity of the Shonai River be improved to modern standards? The report has been divided in four phases. The first phase is used to formulate the final research question. This phase focuses on which part of the Nagoya urban area is most prone to flooding. Three kinds of flooding were examined: by peak river discharge, impact by tsunamis and impact by storm surge. The area is already well protected against tsunamis due to the natural shape of the bay Nagoya is situated to. The coastline is well protected against storm surges in the second half of the 20th century. At the river banks however, flood safety is still below the desired level. In the area, risks are relatively high along the Shonai River. Therefore, it has been decided to focus on the threats around the Shonai River. As already described above, there are several locations along the river with safety risks. In phase 2, several locations and solutions are described to increase the capacity of the river. One major problem is the bottleneck around the Biwajima bridges, where four bridges are narrowing the river. At this location, the desired safety level of a flood discharge occurring once in 200 years is still far away. After discussion with officials of the Shonai River office, it was found that this problem was most urgent. Therefore, it had been chosen to elaborate further on this option in phase 3 and 4. In phase 3, several options are described to remove the bottleneck. The first option is to replace the bridges with more clearance and larger spans. The second option is to remove the bridges and replace them for tunnels. The third and last option is to construct a bypass along the river, with flow through a tunnel. The Shonai River office is already working on a plan to raise the bridges, thus the first option has been dropped. The second option required large amounts of space for the tunnels. Therefore, it had been decided to work out the third option of creating a bypass. To minimise the impact of such a bypass and its construction on the surrounding area, the decision is made to construct a bored tunnel. In the fourth and final phase the solution is verified. This is done concerning structural, hydraulic and construction method aspects. All the aspects are found to be possible. In hydraulic aspect, it is found that the required discharge capacity to reach a once in 200 year safety level equals 4250 m3/s. The current discharge capacity is found to be 2850 m3/s. Therefore, the bypass should have a minimal discharge capacity of 1400 m3/s. When using a bored tunnel, it is found that two tunnels with the maximal internal diameter of 16 m should be applied. On top of that, because the concrete surface is to rough in the best circumstances, it was decided to apply an epoxy layer on the surface. Using such a layer, it is found that the total discharge capacity becomes 1490m3/s. The construction of the tunnel would take 137 weeks to complete. The total costs are estimated to be in the order of ¥60,000,000,000, or 60 billion yen, equivalent to 463 million euro. In comparison, the plan of the river office to replace the bridges would cost ¥68,400,000,000. It can be concluded that this option is a reasonable alternative for the current plan.

Amsterdam faces the challenge of maintaining a domain of 200 km historic quay walls, which is a vital part of the city’s historical landscape. Many quays are currently in poor condition and require renovation or replacement in the near future, significantly impacting the city. The quay walls can be up to 300 years old and their structure consists of a masonry cantilever wall on top of a timber floor, which is supported by headstocks founded on multiple vertical timber pile rows. In recent years, quay walls have shown signs of damage, partial collapse, and early warnings of such events. The most recent and severe incident was the collapse of the Grimburgwal in 2020, where approximately 20 meters of quay wall suddenly collapsed, plunging into the canal within a matter of seconds. Consequently, it is important to be able to predict the resistance of these structures and understand their potential failure mechanisms. The most common and severe failure mechanism observed in Amsterdam’s city centre is the lateral failure of the pile foundation. Calculating the resistance against this mechanism with existing models, leads to estimates of insufficient strength and safety. It seems that these models are too conservative, because in reality, the majority of the existing structures that proof unsafe on paper is performing quite well in practice. The discrepancy between the models and reality arises from uncertainties in the working principles of historic quay walls, geometrical unknowns, as well as uncertainties in soil and structural properties. This thesis provides a comprehensive understanding of the lateral failure of the pile foundation by full-scale quay wall experiments and it proposes a computational model to predict the resistance against this failure mechanism. To gain a comprehensive understanding of the lateral failure mechanism, an unique and extensive experimental program has been conducted on an existing historic quay wall, founded on timber piles. The quay is located at Amsterdam Overamstel and dates back to 1905. Experiments have been conducted at three different system levels. At level 1, four-point bending experiments have been performed on individual piles to obtain the bending material properties. At level 2, lateral pile group experiments have been conducted on two 3x4 pile groups to study the pile-soil-pile interactions. At level 3, proof load experiments have been carried out on entire full scale quay wall sections, to study the overall behaviour of the quay. As part of the experimental program, an extensive geotechnical site investigation has been performed. The experimental approach chosen enables a stepwise validation and calibration for computational quay wall models. Through the experimental program, it is demonstrated that among all potential failure mechanisms, the lateral failure mechanism is most likely to occur when a quay wall is subjected to large surface loading at its backside. Examples of such loads in practice are parked or moving cars, heavy vehicles or goods. The mechanism is triggered by an increase in soil stresses at the backside of the quay, which pushes the foundation towards the water. This, in turn, results in the bending of the timber piles, accompanied by the development of bending stresses. State-of-the-art models (ABAQUS, PLAXIS and spring models) were used to predict the failure surface load of the Overamstel quay, with an estimated value of approximately 20kPa. However, in reality, the quay demonstrated significantly greater strength, as failure was not observed even for loads as high as 55kPa. While part of this underprediction can be attributed to experiment-specific effects not considered in the prediction analysis, the substantial underprediction of the failure load still emphasizes the conservatism in current modelling approaches. Clear indicators of the lateral failure mechanism include the inclined position of the top of the piles, broken piles, settlements at the backside of the quay, and lateral deflection of the foundation. These indicators can effectively be monitored, as demonstrated by the employed monitoring plan in the experiments. Elements of this plan, such as inclination sensors mounted on the pile caps, can be implemented in Amsterdam’s city centre to detect signs of lateral failure. The foundation piles experience fracture when they reach a state of full yielding, which occurs when the bending stresses in the timber surpass the modulus of rupture across the entire cross-section of the pile. Bending experiments conducted on timber piles indicate a substantial variance in both the modulus of rupture (variation coefficient of 0.26) and the modulus of elasticity (variation coefficient of 0.3). Consequently, the piles exhibit a wide range of flexural stiffnesses and bending moment capacities. These discrepancies stem from natural variability and biological degradation of the timber, which lead to the formation of a weakened outer layer or “soft shell” starting at the perimeter of the piles, going inward. The soft shell thickness is approximately 10% of the external pile diameter and it does not contribute to the structural strength of the piles. The substantial variations in load carrying capacities within a timber pile group can be primarily attributed to the variations in pile stiffness and bending capacity. Surprisingly, typical pile group effects such as in-line, side-by-side, pile free height, and pile diameters do not have a large contribution to the variations in individual lateral pile resistances found. When multiple piles are considered together, significant variations between individual piles compensate each other, leading to a group resistance that was almost identical in the two pile group experiments. This finding is advantageous from a computational modelling and risk assessment standpoint. Within the tested pile groups at the Overamstel site, with 200-300 mm diameter piles, partial yielding starts at approximately 100 mm of group deflection. The first pile breakages are expected to initiate at 140 mm of deformation; however, due to the redistribution of lateral loads among the piles, it does not directly result in group failure. Nevertheless, when deformations exceed 200 mm, a majority of the piles will break, leading to group failure. It is vital to emphasize that the transition from the initial onset of yielding to group failure requires merely a slight additional lateral load of 15%. An analytical quay wall model has been developed to predict the resistance against lateral failure of historic quay walls. This model comprises a framework of elastic beams embedded in an elastic foundation, which is externally loaded by a linear elastic soil model based on Flamant’s theory. The framework is made up of multiple Euler-Bernoulli beams, connected to each other by boundary and interface conditions. The stiffness of the connection between piles and headstock is described by a pile-headstock interface model. The elastic foundation is represented by a series of independent p-y springs, approximated with a bilinear elastic-perfect-plastic model. A method is developed to include the pile-soil-pile interaction and the influence of a sloping surface by adjusting the plastic branch of the p-y springs. This method has been validated through multiple experiments documented in literature in which steel piles were used, eliminating material property uncertainties. The analytical quay wall model has been validated and calibrated with the Overamstel quay wall experiments, employing the stepwise approach. In the first step, the bending properties of the timber piles were obtained from the level 1 bending experiments. Subsequently, in the second step, the model’s capability to describe laterally loaded pile groups was validated through the level 2 pile group experiments. Finally, the Flamant soil model and the model’s ability to describe a historic quay were validated using the level 3 quay experiments. As a final step, the model was compared with finite element computations, demonstrating a good agreement in displacements and forces. The analytical quay wall model accurately predicts lateral displacement, pile bending moments, and bending stresses at various depths, allowing for the assessment of pile fracture under specific surface loads. Its key advantages over state-of-the-art finite element modelling software include robustness, computational speed, feedback loops (e.g. force and displacement-dependent pile-headstock connection stiffnesses), minimal input requirements, and no numerical stability issues at large deformations. The model is highly suitable for trend analysis, sensitivity studies, and probabilistic analysis due to its short computational time in seconds, compared to complex three-dimensional FEM software that takes minutes to hours. The effectiveness and potential of the validated analytical quay wall model have been demonstrated in two “follow up” studies, described below. In the first study, the quay model has been employed to investigate the failure of the Grimburgwal. With the model it was demonstrated that bending stresses in the timber piles exceeded the modulus of rupture as a consequence of local deepening of the canal in front of the quay. It therefore provides valuable insights for Amsterdam’s historical centre. The analyses have served as an additional validation step for the analytical quay wall model developed in this thesis, specifically for applications to the quay walls of Amsterdam’s historical centre. In the second study the quay model has been used to effectively showcase the potential of Bayesian updating by incorporating evidence of survived loading situations and corresponding deformations. This approach enables refinement of the reliability predictions and parameter distribution uncertainties, leading to a more accurate prediction of the resistance against the lateral failure mechanism of quay wall foundation piles. Depending on the type of evidence, an a-priori reliability prediction for a quay wall that fails to meet safety standards can be updated to any of the three consequence classes (CC3, CC2, and CC1b) outlined in NEN8700. In a fictive case study, a quay wall with an a-priori reliability of β = 1.5 has been increased to β = 3.2 by including evidence of an extreme survived load of 10 kN/m2 that resulted in displacements of less than 4mm. This is a decrease in failure probability by two orders of magnitude, showing the potential impact of using observational information in combination with Bayesian updating The main practical implication of this thesis has been the improvement in modelling accuracy, as a result of the Overamstel experiments. The revised “gain” in modelling accuracy for bending moments and deflection was 43% and 37% respectively. This improvement can be attributed to advancements in modelling techniques, such as accurately simulating pile-soil-pile interaction and modelling the pile-headstock connection, as well as utilizing precise location-specific geotechnical and structural material properties as model input. The improved modelling accuracy results in a less conservative evaluation of the quay walls, leading to a reduction in the number of unnecessarily rejected quay walls for the Amsterdam quay wall domain. The most practical recommendations for Amsterdam are: a) to develop accurate techniques for mapping quay wall configurations, b) to implement comprehensive quay wall monitoring systems in the city centre, c) to utilize the analytical model in future studies and assessments, d) prioritize geotechnical site investigations before making model predictions, and e) perform non-destructive tests in the city centre and incorporate this information in the assessment. The methods and insights developed in this dissertation enhance the understanding of the lateral failure of historic quay walls and enable more precise predictions of their resistance against such failures. As such, the model can be effectively used to support decisions on their safe use, remaining service life, and the need for their replacement.@en

The submerged floating tunnel (SFT), also known as the Archimedes bridge or suspended tunnel, is a conceptual idea for a tunnel that floats in the water, supported by its buoyancy. The tunnel would be placed underwater, not too deep in order to avoid high water pressures, but deep enough for it not to be exposed to extreme weather conditions or obstruct shipping traffic. The tunnel is kept in position with tethers that are anchored to the sea bed or floating pontoons at the water surface. This thesis focuses on the tether supported SFT. The dynamic response of a tether supported SFT, in a hydrodynamic environment, is different from the tunnels that are widely used nowadays. The SFT is always in contact with open water in which it is moving due to the hydrodynamic environment. The dynamic response of the tether supported SFT is still a gap in our engineering knowledge and this contributes to the fact that world-wide no tether supported SFT has ever been constructed. Many research has been performed in the last years. A broad range of models has been used to study the dynamic behavior of the tether supported SFT. The key in all these models is to capture the fluid structure interaction. Waves and current exert forces on the tunnel body but at the same time, the presence and motion of the tunnel body affects the wave-current environment. To model the dynamic response of a tethered SFT incorporating fluid-structure interaction, a new model has been developed. The dynamic SFT model describes the cross sectional motion and tether forces of a rectangular tubular tunnel which is pinned down by two inclined tethers, excluding longitudinal effects. The tunnel is forced by waves and current only. When assuming the SFT system to be linear, the motion of the SFT can be seen as a superposition of the motion of the tunnel body in still water and the forces on the restrained tunnel body in waves and current. The tunnel motion in still water is modelled with a dynamic module while the hydrodynamic forces on a restrained tunnel body are computed with a wave force module. The two independent modules are combined in a coupling module which makes it possible to describe the dynamic response of a tether supported SFT in a wave-current environment. The advantages of this model choice are the fast computational time and the convenience of physical interpretation. The wave force module computes the wave-current forces on the restrained tunnel body with a modified Morison formulation. This formulation is capable of computing, besides vertical and horizontal wave-current forces, the rotational wave force. Rotational wave forces are essential in the determination of tunnel roll motion and cannot be determined with the classical Morison theory. Just like the classical Morison theory, the modified Morison formulation does not take into account wave field deformation due to the presence of the tunnel structure. Therefore, for waves that are short compared with the dimensions of the SFT, diffraction effects cannot be taken into account. The absence of the diffraction effect is corrected for by integrating the dynamic pressures, water accelerations and water velocities with respect to the tunnel height and width. It should be noted that the applicability for short waves is only valid in case of structures that are submerged at a depth of at least 1.5-2 times the structure height. For shallowed submergence depths, the diffraction effects in combination with wave deformation become too large which cause prediction errors in the force determination. The force on the restrained SFT due to a uniform current can be modelled with the drag force expression from the classical Morison equation. To correct for the wave current interaction, the hydrodynamic mass coefficients are adapted as function of the Keulegan-Carpenter number. The dynamic module describes the oscillation of the SFT, in still water, with a dynamic system. A free floating tunnel has three degrees of freedom which are roll, sway and heave. This dynamic system assumes the tunnel is connected with two in-extensible tethers. Adding two rigid constrains to the free floating tunnel reduces the SFT to a single degree of freedom system. This single degree of freedom system describes a coupled translational (sway) and rotational (roll) motion around an instantaneous rotational point which can be found at the intersections of the tether axes. When assuming small vibrations, the instantaneous rotational point remains fixed at the intersection of the tether axes when the tunnel is at rest. The moment of inertia of the SFT is obtained by using the Lagrangian approach which is based on energy conservation. Because the structure is submerged in water, added damping and mass terms are used in the equation of motion. The magnitude of these damping and mass terms is calibrated with physical model experiments. The coupling module combines the wave force module and the dynamic module, which makes it possible to formulate a full equation of motion, describing the oscillation of the SFT in a wave current environment. From the equation of motion the sway and roll motions, containing accelerations, velocities and displacements, can be obtained. Apart from the motions, the tether forces can be predicted. The dynamic SFT model is validated with physical model experiments. With this dynamic SFT model, a parametric study has been performed. The first part of the parametric study focuses on the motion of the SFT. The second part examines the tether forces. Furthermore, the slack-taut transition and the safety against fatigue have been investigated. The parametric study does not take into account current. The most important findings and implications are in summary: • Each SFT configuration has a different response to the wave environment. Hence, every configuration has a different critical wave length for which the dynamic response is maximum. This critical wave length is independent of the wave height. It should be noted that the dynamic response is a comprehensive term which consists of many variables. These are; tether forces, sway motions and roll motions of which both motions contain accelerations, velocities and displacements. The most dominant parameters to influence the dynamic response are the buoyance to weight ratio (BWR), tether angle and submergence depth. • The BWR increases the stiffness of the dynamic SFT system which causes a decrease in the roll motions and sway displacement. Due to the stiffness increase, sway accelerations and velocities become larger. The natural frequency of the SFT is increased by increasing the BWR, which makes it more sensitive to shorter waves. • Configurations with large tether angles have the character to be very flexible and sway dominant, while configurations with small tether angles are stiffer and roll dominant. Tether forces for configurations with large tether angles are more sensitive to long waves, while tether forces for configurations with small tether angles are more sensitive to short waves. • A decrease in submergence depth increases all tunnel motions and tether forces, as the tunnel becomes more exposed to the wave environment. The dynamic response of the SFT becomes more sensitive to short waves. • An increase in anchorage depth results in larger tunnel motions. The increase in tether forces is negligible. • Placing the tether connection sideways of the tunnel body results in smaller roll motions and larger sway motions. Lowering the tether connection with respect to the tunnel bottom is favourable for all tunnel motions. The manner of how the tether connection is orientated, with respect to the tunnel body, has small influence on the tether forces. • Increasing the BWR, submergence depth or both reduces the risk of snapping lines and tether fatigue. Configurations with small tether angles have a smaller risk of having line snapping and tether fatigue compared to configurations with large tether angles. This study gives a supplement to the classical Morison theory. Morison’s theory is modified which makes it possible to compute rotational moments due to wave loading. Also the applicability to short waves is enlarged. A new dynamic schematization is developed which makes it possible to describe the dynamic response of a SFT as a single degree of freedom (SDOF) system. The advantages of this dynamic schematization are the fast computational time and the convenience of physical interpretation. The results obtained from this research study can be used as a preliminary design tool. In an early design stage, motions and tether forces can be predicted. Also measures to reduce these motions and tether forces can be investigated using the dynamic SFT model. Design graphs to estimate the snap-taut transition and for safety against tether fatigue are provided. It should be noted that this dynamic SFT model should not be used for detailed computations in later design stages.

From the 3500 kilometers of primary flood defenses in the Netherlands, a third does not comply with the current standards. As a result, over 700 kilometers will be strengthened in the upcoming years. Traditional strengthening of dikes consists of strengthening with soil and requires space that is often not available. Further strengthening of dikes, therefore, requires smart solutions, which increase the strength, without changing the dikes cross-sectional area. One of these solutions is the use of sheet pile walls as stability screens. However, in contradiction to all commonly used design codes, including the Eurocode, the current design approach for stability screens in dikes does not allow for plastic calculation. Furthermore, a model factor of 1.1 is applied to the forces and moments, when the sheet pile is applied as a panel. These two aspects make the application of sheet piles as stability screens expensive to apply. A better understanding of the failure behavior is needed to clarify whether the current design approach is conservative. Within the scope of the Flood Protection Program, a cross-project exploration was formed between water boards and the national government at the end of 2014. This collaboration is called POV and the aim is to innovate dike reinforcement which will result in a better, faster and cheaper process. A separate branch of this organization, POVM, is focusing on macro-stability. Within this scope, the use of sheet pile walls as stability screens is investigated. In this context, the Eemdijk test has been performed. This consisted of two full-scale tests up to failure. Although the test was successful and led to many new insights, the reliability of strain measurement data is questionable. The strain distribution, however, is essential in understanding the failure behavior. That is why this thesis addresses the reliability of the measurement data. This is done by means of comparing measurements of different sensor types. Each sensor is then classified using four classes that indicate the reliability. Subsequently, reliable data is used to obtain a curvature distribution. In order to convert strains into moments, a moment-curvature diagram is required, which relates curvatures to moments in the sheet pile. This relationship is obtained by means of finite element calculation of a 4-point bending test. Subsequently, the chosen model is calibrated by means of reproducing the measurement results of three real documented 4-point bending tests. Finally, the model is applied to the sheet pile profiles used in the Eemdijk test. With the obtained moment distributions, conclusions are drawn with respect to the current design approach. Furthermore, recommendations are made with regards to the applied monitoring program and the influence of soil on local buckling.

The submerged floating tunnel (SFT) is a conceptual idea that originates from the 19th century. The idea consists of a tunnel tube floating underwater where it is kept at a fixed depth by its buoyancy and by tethers that are anchored to the seabed and or by floating pontoons at the water surface. The tunnel is placed deep enough to avoid extreme weather conditions and to not hinder marine traffic but also not too deep to avoid high hydrostatic water pressures. The dynamic behaviour of this structure differs largely from classic immersed tunnels as it is not embedded in the bed and also from that of (suspension) bridges due to the hydrodynamic environment. This makes the dynamic behaviour of the SFT largely complicated and to this day still raises a lot of questions. This limited understanding contributed to the fact that worldwide not a single SFT has been constructed yet. For this study, the dynamic response of a tether-supported SFT due to an earthquake will be analyzed. The main goal is to identify the main behaviour of an SFT due to these seismic events, to get an idea of how severe the damage could be and to know which measures in the design could be applied to reduce the impact. To do so, a case study is introduced where the main dimensions of the tunnel are described. Next, a cross-sectional analysis is performed. This is done both analytically and by the use of the finite element model (FEM). The purpose of these analyses is to verify the input of the FEM. For the analytical model, a singular tether is described as an Euler-Bernoulli beam. By applying the Fourier transform method of analysis, the dynamic behaviour of this tether due to a simplified input signal is obtained. Subsequently, the same tether is modeled as a FEM by the use of DIANA FEA. By performing a time-history analysis for the same simplified input signal, the same results as for the analytical analysis are obtained which verifies the input. After that, the simplified model is used to model the entire tunnel which is used to study the dynamic behaviour of the SFT. To perform the seismic analyses for the total tunnel, three different accelerograms of three different earthquakes are used. Before applying these signals to the model each of them is scaled to the spectra described by Eurocode to gain a more general input. The model is then used to perform two types of analysis. First, an eigenvalue analysis to gain the eigenperiods of the structure. Next, a time-history analysis to gain the seismic response of the structure. For the time-history analyses, the input is applied in the transverse and in the longitudinal direction, each as a separate analysis. From these analyses, the displacements and tension stresses in both the tunnel elements as in the tethers are obtained. The last part of the study is used to analyze the effect of different design aspects of the tunnel. By using the case study as a starting point, multiple configurations are tested in where the effect of the number of mooring lines, number of tethers, tunnel alignment, tether inclination and the appliance of base isolation systems are examined.

This thesis aims to gain insight into the global dynamic fluid-structure interaction response of a submerged floating tunnel (SFT) under the wave and current loading to enhance the design. To this end, the tunnel tube is modelled as a Euler-Bernoulli beam deformed in three directions (horizontal displacement, vertical displacement, rotational angle), the discrete anchoring system as a continuous elastic foundation considering geometrical nonlinearity. Then, the Morison equation is used to model the combined current and wave loading and the oblique wave loading. A simplified wake oscillator and a non-simplified wake oscillator are used to model the vortex-induced vibration (VIV) under current loading. Subsequently, the modal superposition method and Runge-Kutta method are applied to obtain the response of the SFT in the time domain. The Fourier transform and the wavelet transform are applied to the time domain signal to perform a frequency domain analysis. Finally, a test on a scaled SFT model is used for a case study. A parametric study is carried out based on the results to study the influence of the geometrical and structural design parameters. The results show that the motions in the horizontal direction and the rotational direction are significantly coupled together. Geometrical nonlinearity introduces the second-order effect to the system leading to a complicated vertical motion with a considerably larger displacement compared with the linear case. The amplitude of the VIV on the tunnel tube of the scaled model is very small based on the non-simplified wake oscillator. Moreover, it is found that, basically, increase of the BWR, increase of the stiffness in the cables, increase of the distribution of the net buoyancy in inclined cable, decrease of the tunnel length or decrease of the inclination of the inclined cables can reduce the maximum response of the SFT. Based on the above findings, it is concluded that a global dynamic analysis is suggested when a SFT is expected to be subjected to oblique wave loadings. Geometrical nonlinearity is necessary to be considered for an accurate analysis especially for the response in the vertical direction. It is also necessary to be considered when the influence of the BWR is of interest. The VIV on the tunnel tube is negligible base on the scaled model.

The influence of surface roughness and shape on the submerged floating tunnel is investigated in wave and current conditions. The hydraulic forces caused by varying tunnel shapes and roughness designs are measured and analyzed.

In the Netherlands a large variety exists in the used widths of inland port entrances. In addition, multiple entrance layouts are applied. Currently, guidelines are missing for the design of inland port entrances along flowing waters with flow velocities larger than 0.5 m/s. A more generic insight into the minimum required nautical safe entrance width and most efficient entrance layout can reduce the design costs and time. The objective of this research was to find the minimum required nautical safe entrance width for generic situations for inland ports along flowing waters in non-tidal areas. To find this minimum safe entrance width, the most efficient entrance layout was determined. The influence of different design parameters was studied to provide the most efficient situation. Moreover, an insight into the influence of these parameters was needed to determine the effect on the most efficient situation when changing these parameters. A fast-time simulation study was chosen to analyse the influence of different design parameters on the entrance width. A rectangular entrance layout and a mathematical ship model comparable with a loaded CEMT class Va ship were used. Flow velocities between 1.0 and 2.5 m/s were taken into account. Moreover, the influence of the waterway width, entrance width, length and angle were analysed with the simulation study. The fast-time simulation program SHIPMA was used to perform the simulation study. As a result of the simulation study, it was found that the most efficient entrance angle is 120 degrees. Note that this is an entrance orientation in downstream direction. Also from a viewpoint of minimising siltation, this angle is more favourable than an angle of 90 degrees or smaller. The required entrance widths for arrivals sailing upstream and manoeuvring forward into the port are circa 55 and 80 meters, for flow velocities of respectively 1.0 and 2.5 m/s. For the determined most efficient layout, the forward manoeuvres into the port when sailing downstream were replaced by backward manoeuvres. For these backward manoeuvres the required entrance widths are circa 70 and 90 meters, for flow velocities of respectively 1.0 and 2.0 m/s. A linear relation was observed between the flow velocity and the required entrance width. For the most efficient entrance layout, it was found that the sensitivity of the entrance length, width and angle was small. These results are only valid for an available waterway width larger than 90 meters. For smaller waterway widths additional research is required. Furthermore, it should be mentioned that the limitations of the SHIPMA model also apply for the acquired research results. The most important limitation is that human interference was not included in this research. Besides, only a limited amount of design parameters was included in the simulation study. Additional research is required to study the influence of other design parameters on the required entrance width.

Floating bridges are found at locations where deep water must be crossed for a long distance, such as in Norwegian fjords. The superstructure of the existing floating bridges is usually constructed from steel. In a marine environment these bridges are exposed to dynamic wave loads. As such, the current floating bridges suffer severe damage due to corrosion and fatigue. Using fiber reinforced polymer instead of steel could alleviate these phenomena and reduce maintenance costs. However, the lower stiffness could cause undesired vibrations in the floating bridge. Therefore a parametric model is developed to investigate the influence of design parameters on the dynamic response of a floating pontoon bridge. A literature study is performed to find suitable concepts and techniques to develop the floating bridge model. A floating pontoon bridge can be schematized with rigid bodies, Euler-Bernoulli beam elements and linear springs and dashpots. The fluid-structure interaction is taken into account by including the added mass, hydrodynamic damping, hydrostatic stiffness and wave force transfer functions of the pontoons. A frequency domain approach is used to compute the dynamic response. A parametric model of a floating pontoon bridge to predict the dynamic response is developed in Python. The hydrodynamic properties of the pontoons are computed by Diffrac and are used as input for the Python model. The Bergsøysund bridge is used as a reference case, because measurement data of this bridge’s dynamic response is available and can be used for validation. The geometrical and structural properties of the Bergsøsund bridge are used to model its dynamic response. Wave conditions with a peak frequency at 2 rad/s are used. The results show that the response of the pontoons is governing compared to the response of the superstructure and that the dominant degree of freedom is sway. The fourth sway mode is the main contributor to this dynamic response. A comparison with measurement data shows that the produced response spectra are in good agreement with the measurements in terms of the peak locations. In the parametric study the influence of single design parameters on the dynamic response of a floating bridge is investigated independently. The results show that the length of the superstructure has the biggest influence on the dynamic response of the floating bridge. In general, a reduction in stiffness in the superstructure leads to a lower overall frequency response function and thus to a lower dynamic response. Increasing the stiffness or reducing the mass of the bridge shifts the eigenfrequency of the fourth sway mode to a higher frequency and vice versa. Finally, when the damping is increased, the peaks in the frequency response function decrease and thereby the dynamic response in resonance reduces. In conclusion, the dynamic response of a floating end-supported pontoon bridge is mainly influenced by the stiffness of the superstructure. A fiber reinforced polymer superstructure should be designed sufficiently stiff, especially in lateral direction, to keep the overall frequency response function low enough.

The submerged floating crossing (SFC) considered in this study has demonstrated significant sustainability based on provided assumptions. the SFC has appeared to be a sheltered and sound idea appropriate to satisfy its expected capacities and to tackle given environmental conditions. The structure of the proposed SFC is intended to withstand all functional and environmental loads. The results of worst-case scenarios showed the base SFC design have a sufficient robustness to withstand the presumed significant loads. Some major uncertainties were faced throughout the study, which are manageable by means of modern technologies in civil engineering or some organizational arrangements.