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.

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.

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.

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.

A submerged floating tunnel (SFT) can be a promising solution for crossing a deep or wide waterway. This tunnel concept will consist of an immersed tube, either attached with anchor cables to the seabed or attached to pontoons floating on the water surface. The reliability of the tether-stabilized SFT is assessed in this research. A suitable target reliability is determined in order to design a full probabilistic SFT. Subsequently, a calibration of partial factors from Eurocode is performed. The robustness of the structure is also analyzed and improvements are suggested. Important failure mechanisms are defined as yielding and slackening of the tethers, longitudinal failure and transverse shear failure of the tube. A first-order reliability method (FORM) and a Monte Carlo simulation (MC) are performed for the limit state functions of these mechanisms. Design parameters are determined so that a target reliability index of 3.8 is met, because of consistency with Eurocode. Consequently, the design points from FORM are used to calculate partial factors for different loading types. The calculated factors and the general partial factors from Eurocode are compared. Slackening of the tethers proved to be the governing failure mechanism in this analysis. The resistance against slackening depends on the force equilibrium, whereas the resistance of the other mechanisms depends on structural strength. The influence factors from the FORM analysis indicated that permanent loading parameters were dominant, i.e.\ concrete density, water density and tube diameter. It was found that for the strength (STR) mechanisms, the factors from Eurocode result in an overly safe design of the SFT. The calculated partial factors for unfavorable permanent load and variable load are significantly lower than the corresponding general factors from Eurocode. For the equilibrium (EQU) case, Eurocode is not safe to be applied. The general partial factor for the unfavorable permanent loading is insufficient. The robustness of the structure is assessed by considering important scenarios. Excessive leakage has large consequences and will result in global structural failure. However, it has a low probability of occurrence. Mitigating measures are available to prevent failure due to leakage. Furthermore, an SFT will be constructed at a specific location. Wave conditions and geolocation need to be taken into account to reach an optimal design. At a depth of 30 meters, the impact of waves becomes insignificant. Lastly, failure of a single tether should not result in failure of adjacent tethers (i.e. progressive failure). A redundant system can be created by installing more or higher quality tethers. Consequently, when all four tethers of one element fail at the same time, this does not result in longitudinal failure. Overall, it was demonstrated that the reliability requirements of the SFT can be met in the design. Moreover, the design can be optimized by a full probabilistic calibration of partial factors.

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.

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.

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.

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.

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.

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.