The energy market is growing and noise regulations for offshore foundation pile installation grow stricter. New initiatives arise to comply with the ongoing developments in the field, such as the BLUE Piling Technology under development by IQIP. Its features are presented as reduced underwater noise levels during installation, which is attibuted to the lower pile wall vibrations caused during driving. In this thesis, the design and execution of a field test is described, identifying the most important differences in geotechnical aspects between a prototype Blue Piling hammer and a conventional impact hammer, the IQIP Hydrohammer S-30. The results show that the Blue Piling hammer creates a response between pile and soil that is very different from a conventional impact hammer. The fundamentally different soil response led to pile plugging during the field test, affecting the stresses around the pile tip. This phenomenon is unlikely to occur during monopile installation, but scaling the test results requires further research.

For the first time in the Netherlands, the construction method top-down cut-and-cover with compressed air will be applied as primary construction method for the construction of two tunnels in deltaic soil conditions. Nowadays a low degree and a short period of disturbance is more and highly valued when it comes to construction methods. Cut-and-cover with compressed air differs from traditional construction methods in that during excavation and construction of the tunnel floor, compressed air is used to maintain horizontal and vertical equilibrium. Instead of working completely top-down, the tunnel is constructed beneath the tunnel roof in a train like motion, called the construction cycle consisting of (1) Groundwater control, (2) Excavation and (3) Construction tunnel floor. The feasibility of the cut-and-cover with compressed air construction method depends on the construction schedule, a faster construction schedule will increase the feasibility. Wet excavation with this construction method is not desirable. To achieve a fast construction schedule, dry excavation is vital. This research focuses on the groundwater control methods that are feasible to apply for the construction of cut-and-cover tunnels with compressed air to ensure dry excavation. The feasibility of a groundwater control method depends on the period necessary for groundwater control and the deformations induced by the groundwater control method itself. Important soil parameters influencing the result of groundwater control are the resistance of the soil and the corresponding Soil-Water Characteristic Curve. The application of compressed air will lead to an increase in the water volume released from the soil, due to a shift in the Soil-Water Characteristic Curve. Compressed air as an exclusion method is not a feasible groundwater control method in low permeable soils. The groundwater control period with compressed air is higher than the resistance of the soil deposits. The resistance value of low permeable soils are often significantly higher than the construction cycle schedule. Suitable groundwater control methods studied in this research are compressed air with vertical drains, vertical dewatering, horizontal dewatering and combinations of dewatering with compressed air. For the case study groundwater control methods are analyzed. The groundwater flow calculations are performed with a coupled SEEP/W and AIR/W calculation to determine the groundwater control period. The deformation analysis is performed with Plaxis 2D. Groundwater control with compressed air with vertical drains has the most effect on the volume of water discharged during the 12 days groundwater control period. With the study is determined that in between 33% and 43% of the required volume for dry excavation is removed in 12 days. The resistance value becomes less important with a decrease in center-to-center distance of the vertical drains. Deformations that occur during the groundwater control period do not have an influence on the total deformation during the final stage of construction. It is recommended to perform a field test to generate data that can lead can lead to more knowledge and therefore a more feasible construction method.

Bridges are a crucial part of the dense Dutch highway network. Almost 50% of the current bridges are built between 1960 and 1980 for an intended service life of 50 years and thus they might reach the end of their lifetime in the near future. This strongly indicates that a large challenge can be expected regarding infrastructural replacement. In current practice, the replacement of bridges within the highway network often leads to substantial traffic hindrance, which has a large negative impact on the Dutch economy. Therefore reduction of traffic hindrance – together with sustainability – is generally an important quality criteria in MEAT-procedures (Most Economic Advantageous Tender) for tender assignments. In order to prepare for the upcoming replacement challenge, there is a need for contractors, the government and product suppliers to invest in the development of a sustainable tender strategy now. The main objective of this thesis was to propose a tender strategy that incorporates sustainability and in particular the reduction of traffic hindrance into a technically feasible design. An extensive literature review has led to a quick bridge replacement strategy consisting of three time-reducing actions, listed according to their potential profit in construction time: 1. Select the Accelerated Bridge Construction (ABC) approach: By means of lateral sliding or transportation by SPMTs (Self-Propelled Modular Transporters) entire superstructures can be constructed off-site and transported to their final location in a matter of hours. 2. Retain the existing foundations: In terms of on-site construction time it would be beneficial to retain the existing foundations. Additionally, theory suggests that a profit in bearing capacity can be obtained compared to the current design codes, which might lead to the total elimination of additional foundation elements required. 3. Avoid intermediate supports: Less elements are required if intermediate supports are avoided in the new bridge design. This does however lead to longer spans, and to prevent additional groundwork activities from an increase in deck height a higher slenderness must be obtained. Furthermore, the new superstructure design must be as light as possible, not only to allow for foundation retainment, but also to facilitate transportation and speed of erection. In particular, the technical feasibility of these actions - both separately and combined - required more research. A case study considering a two-span plate bridge was used to investigate these strategy actions. Research was done into the obtainable profit in retained pile foundations and the application of UHPC in a slender and lightweight bridge concept. It was concluded that the proposed tender strategy has a high potential. Not only is the on-site reduction time diminished but the retainment of the existing foundations and the application of UHPC in a slender and lightweight superstructure may also lead to a highly sustainable design.

In March 2016, an addendum to the Dutch design guideline for micropiles, CUR 236, was published. This addendum elaborated on the ‘axial stiffness of micropiles’. The softening behaviour was here first mentioned as an aspect relevant for the axial stiffness of the micropiles. Due to the slender geometry of the micropiles, this further translates into axial capacity. Up to this moment very little research was done into this phenomenon and to be conservative a ‘best guess’ of 50% of the peak shear stress was made. The goal of this thesis is to have a more profound understanding about this (strain) softening behaviour, leading to the main research question: “How does strain softening manifest for micropiles under tensile loading?”. This strain softening behaviour can be further subdivided into the mobilisation from peak to residual shear stress and the reduction of the residual shear stress relative to the peak. Furthermore, the installation effects play a big role in the bearing capacity. Also, some thought is given to the large scale measurements of the behaviour. Three different paths are chosen to research the strain softening behaviour. Numerical modelling, small scale tests on sand and large scale pile tests are performed. In case of the numerical modelling, the large scale situation is simulated in the numerical software Plaxis, using an axisymmetric model and the hypoplastic constitutive model. Direct shear tests are assumed to represent a small part of the micropile, simulating the local softening behaviour. Numerous tests are performed varying relative density and top pressure to assess the local strain softening behaviour. Last, a method is developed to quantify the occurring ratio between peak and residual shear stress in-situ, extending on the current prescribed testing procedure (CUR 236, 2011). The only constitutive model available that describes the critical state soil behaviour for sand is the hypoplastic sand model. However, the combination of the tensile loading, softening implementation into the hypoplastic sand model in Plaxis and the deformations, induce considerable inaccuracies and physically impossible behaviour. This rejects further elaboration with this approach. The direct shear tests are performed on only sand, based on the results of Uesugi & Kishida (1987), assuming a rough surface. In summary, a clear dependency on relative density and average confining pressure is observed. Varying from a reduction of approximately 30% for samples with the maximum possible density to 0% for a sand with a medium dense packing. Furthermore, the displacements necessary to mobilise from peak to residual shear stress show a uniform trend, independent of relative density or pressure. Quantitatively, the displacement ranges between 2 and 3 mm. In the large scale tests, due to unexpected, structural failure, the majority of the test results, unfortunately, were unusable. The pile test that did produce workable results, behaved as expected. It could be deduced that the used methodology works. The use of the hypoplastic constitutive model in Plaxis, does not give the expected results. It can thus be concluded that a fully coupled stress – strain analysis of the problem is unfortunately impossible. Concluding on the direct shear tests performed, the implementation in the CUR 236 addendum is too simplistic. In terms of ratio between peak and residual shear stress, a dependency based on relative density and average confining pressure should be included. In terms of displacement, the found displacement is larger. It should however be noted that the direct shear tests are only a simplification, approximating the actual situation. The performed large scale tests do show results in line with expectations and could be used in the future to assess the softening behaviour in-situ.

Deployment of renewable energy is essential to reach a carbon neutral economy. Offshore wind farms have caught the interest of many developed countries since they are an essential source of green energy. The interest of this thesis lays in the design of the foundation used for offshore wind farms, in particular the interaction between the monopiles and the scour protection layer. An optimised one-stage installation process for the scour protection is investigated, which consists of first placing the rock armour and then driving the monopile through the entire scour protection layer. This is an efficient method to reduce the installation time and the operational cost. The purpose of this research is to identify the limitations which are related to the penetration of the monopile through the stone armour. The scour protection material is composed of large diameter rocks, which can hinder the penetration of the pile, or even damage the tip of the pile. A restricting ratio of the mean size of the rock (d50) to the thickness of the monopile wall (w) is explored, as well as an investigation of the effect of penetration resistance on different material and geometry characteristics. The first research method employed is a literature study, which proves that the analytical formulation of the axial capacity provided by the available standards is inappropriate for the application of this thesis. Thus, two other research methods are identified, which include designing an experimental small-scale test and a Discrete Element Model (DEM) of a penetration test.

The low lying areas in the Netherlands often consist of soft and low permeable soils like clay and peat on top of a sand layer. Due to high water pressures at the interface between the permeable sand layer and the low permeable top layers, the effective stresses decrease, which can cause lifting of the low permeable top layers. As a consequence a deep seated long slip surface of the inward dike face can occur. Classical solutions to improve inner slope stability, like decreasing the inner slope or creating a stabilisation berm, are space consuming. Stabilisation columns are expected to improve the inner slope stability within the actual footprint. Various effects of stabilisation columns on inner slope stability are studied. The effects are studied by means of PLAXIS calculations using various modelling techniques.

Cities are growing and more land is reclaimed. Reclamation is the process of creating new land from ocean, riverbeds or lake beds. New land is created by hydraulic placement of sand. The hydraulically placed fills are characterized by low densities and show a high variety in packing throughout the field. The relative density of the fills depend on placement method and whether the placement takes place aqueous or subaqueous. After the placement Vibro-densification techniques are used to densify the soil. Conventional vibro-densification techniques have difficulties penetrating hard soil layers to reach the loosely packed layers. This makes that land reclamation is not always financially feasible. The Sonic drilling technique might be used to improve the penetration in hard layers. Reducing the process time make the use of land reclamation more accessible. However, the sonic drill technology is not well understood at the moment. There are no reliable guidelines that make it able to estimate the driveability of a certain profile in to the ground with the help of sonic vibrations. This research focusses on better understanding of the sonic drill technology and the contribution of a sonic drill to a new compaction technique. On a reclaimed land site in Amsterdam an innovative method for installing elements in dense and hard sand layers was tested. The method focuses on sonic drilling/installation with vibrations up to 180Hz to reduce soil resistance whilst pushing the elements into the ground. This method has shown to generate less disturbances to the surroundings whilst achieving a higher penetration rate in comparison to conventional installation methods. The sonic vibrator generates pressure waves at the top of the element. The elasticity together with the inertial properties of the element allow the waves to propagate through the element. The pressure waves travel through the element and become partially transmitted to the surrounding soil. At the sides the mainly shear waves occur while at the tip both pressure and shear waves are present. During the wave propagation energy is lost due to scattering, radial damping and proper damping. The sonic drill technology uses high frequency vibrations to strongly reduce soil resistance. The resistance of the element against penetration is reduced by liquefaction, inertia effects and a temporary reduction of porosity of the soil. The observations from the tests form the basis for the establishment of model which simulates vibratory pile driving. The model is able to describe the installation process for different type of elements. The model might be used in the future to predict the penetration time using only the CPT data. It can be concluded from the tests that the sonic vibration method is an effective solution for installing elements in a short amount of time in challenging ground conditions and with minimal vibration and settlement disturbance. Finally, in terms of further study, it must be noted that several major simplifications and assumptions underlie the model, which may be improved upon with more rigorous constitutive modelling and numerical analysis.

Loose, sandy slopes situated or deposited under water may be susceptible to liquefaction-induced failure. In contrast to 'regular' localised slope failures, flow slides are diffuse, large-scale and potentially disastrous. Earthquake-induced ground vibrations currently dominate the liquefaction engineering scene. In reality, however, many liquefaction failures may be attributed to non-seismic sources of cyclic shear loading, albeit often in less dramatic context. Pile or sheet pile installation form an example. The construction of a new sea lock in IJmuiden brings this issue to the forefront and initiates a series of pile installation tests, conducted in several sandy deposits. The results of these tests are analysed and reveal (1) some key differences with seismic sources of vibration; (2) the importance of the duration and frequency of driving in residual excess pore water pressure (EPP) generation; and (3) the magnitude of spatial and temporal scales on which vibrations and EPPs generally act. The observations from the tests also form the basis for the establishment of a cyclic liquefaction model which simulates vibratory pile driving-induced EPP development. The model is validated using data from the IJmuiden pile installation tests. The cyclic liquefaction model is combined with a constitutive modelling approach for flow, or static, liquefaction behaviour. This enables the creation of a comprehensive strength framework, which allows representative strength parameters, based on the onset of flow liquefaction, to be derived for use in slope stability analyses. This strength framework is rooted in critical state soil mechanics and the related state parameter. A slope stability analysis procedure is advocated in which priority is given to pre-pile installation liquefaction analysis. Given a satisfactorily stable slope, pile installation effects are incorporated, where EPP generation and migration of pore water are considered the dominant contributors to failure. The procedure is applied to a fictional reference slope, where results show significant reduction in safety against global failure during driving. Considering three-dimensional drainage effects, however, suggests that pile installation may only have a minor effect on slope stability, depending on the failure mechanism and volume under examination. From the example stability analysis, some recommendations are made with regard to prevention and mitigation of piling-induced slope failures. Finally, in terms of further study, it must be noted that several major simplifications and assumptions underlie the cyclic liquefaction model and the corresponding method for slope stability analysis, which may be improved upon with more rigorous constitutive modelling and numerical analysis.

The development in harvesting trend of wind energy is evidenced as a result of the Paris convention. Therefore, future wind turbines tend to move towards deeper water, which sets a requirement of larger capacity support structure. The design guidelines of Gravity Based Foundation (GBF) which is capable of supporting deeper water wind turbines lack attention on the cyclic response of the foundation. The undrained capacity of GBF in terms of failure envelope under combined loading is investigated numerically, in order to shed light on the effect of cyclic loads on the capacity of the foundation. A GBF supporting a 5 MW wind turbine on sandy soil domain is designed based on the static conditions. A critical state model called Hypoplastic sand model with intergranular strain concept is adopted to represent the soil domain in 2D. The influence of factors such as relative density (Dr), load characteristics (¿c yc & ¿avg ) and the wave frequency on the pore pressure behaviour are analysed in the event of concluding a critical case. Moreover, it should be noted that the number of cycle is restricted to 50 cycles as a result of limitations in the implicit method. An undrained failure envelope is developed for the critical case, which in comparison with original envelope reveals the expansion in undrained capacity with respect to the number of cycles. It is inferred that the expansion in the capacity is because of the process known as densification which overcomes the effect of pore pressure on the failure envelope. It is also worth noting that the consolidation phase which is used to model the loads has a significant influence on the expansion of the failure envelope.

In the past decade, suction caissons have emerged as a preferred offshore foundation solution for wind turbines due to their silent installation process and potential for recyclability. However, there has been growing speculation regarding the necessity of under base filling, which involves filling the gap between the top plate of the suction caisson and the seabed. Some experts have suggested that under certain conditions, this under base filling may not be required at all. Furthermore, concerns have been raised about the efficacy of under base filling in achieving full contact between the top plate and the seabed, as it has been observed that gaps may persist even after the filling is applied. Consequently, doubts have been cast on the overall need for under base filling. However, there is limited research focused on understanding the behavior of water plugs in the absence of under base filling, at different loading conditions ( Compression , tension , cyclic etc.). This knowledge gap motivates this thesis study, which aims to investigate the behavior of water plugs specifically in dense sand samples, as sand is considered more critical compared to clay in terms of its variability in drainage conditions that can influence the foundation’s performance. To achieve this, a series of centrifuge tests were conducted on suction caissons that were partially installed and some fully installed. The results of the experiments shed light on the role of under base filling in different loading scenarios. Under monotonic compressive loading at higher rates, it was observed that under base filling played no significant role in the load transfer . Both the caissons with and without under base filling exhibited similar load transfer mechanisms, indicating that filling the gap may not be necessary in such loading conditions. Additionally, under tension loading, it was found that under base filling had little to no effect on the development of tensile capacity. By expanding our understanding of the necessity and effectiveness of under base filling, this study contributes to the ongoing discussion surrounding suction caisson design and installation practices for offshore wind turbine foundations.

Monopiles with large diameter (larger than 6 m) and low aspect ratio (less than 6) are increasingly used in offshore wind farms. These foundations demonstrate a rigid response under lateral loading. The validity of the existing design methods, that are based on small diameter flexible piles, has been questioned by both the industry and researchers. In addition, the monopiles are subjected to both lateral and vertical loads. The influence of vertical load on the lateral design of short rigid monopiles in clay soil is not clear. This study aims to perform a comprehensive study on the influence of vertical load on the lateral response of monopile foundations in clay soil. All analysis in this study was performed using 3D finite element modeling in PLAXIS 3D software. The NGI-ADP constitutive model was adopted to simulate the nonlinear mechanical behaviour of clay. Considered in the analysis is a short rigid pile with a diameter of 10 m (L/D = 3) and a long flexible pile with a diameter of 2 m (L/D = 15). The analyzed clay soil profiles consist of a normally consolidated clay soil and an overconsolidated clay soil with a constant undrained shear strength profile equal to 30 kPa. For each pile in each type of clay soil, a pure lateral loading scenario is performed first to assess the validity of current design methods. Subsequently, a combined loading scenario is performed to assess the influence of vertical loading on the lateral behaviour of rigid monopile in clay soil. Results of the pure lateral loading scenario suggest that current design methods heavily underestimate the lateral capacity of rigid monopile foundations in both clay soil profiles analyzed. According to the findings of this study, it can be concluded that current design methods are not fit to provide an accurate assessment regarding the lateral load response of rigid monopile in clay soil. In order to correctly assess the lateral load response of rigid monopile in clay soil, a method consisting of a 3D finite element model akin to the model used in the research or a PISA design model is advised. A potential third design method, the 1D rotational spring model, is also proposed. Results of the combined loading scenario suggest that the presence of vertical loading causes a decrease in lateral and moment capacity of the rigid pile in both clay soil profiles analyzed. However, the influence is negligible when the vertical load magnitude is smaller than 50% of its bearing capacity. To quantify the influence of vertical load on a monopile foundation, a series of load analysis were performed on a real offshore wind turbine with a 5MW power capacity. It was found that the vertical load on a typical monopile foundation in clay is around 27% of its bearing capacity. According to the findings of this study, it can be concluded that the influence of vertical load on the lateral response of rigid monopiles in clay soil is limited and can be ignored in foundation design.

Quay structures play an important role in society. How much load these structures can withstand however is not certain. This MSc thesis contains insight into the load capacity of the old Amazonehaven and the current SIF quay structures. Both are quay structures which use a combined sheet pile wall, a reinforced concrete relieving platform, M.V.-piles, and two rows of bearing piles. The objective of this MSc thesis was to determine the load capacity of the structures, the models should therefore be as close to the actual conditions as possible. For that reason no safety and/or material factors have been applied throughout this MSc thesis. The approach is shown below. A literature study was performed to gain insight into the areas of interest that needed to be studied. This theory in combination with a review of the structures led to the critical cross sections of the respective structures. These cross sections were then modelled with conventional design methods (Blum and D-Sheet Piling). The Blum method determined the individual contributions of several aspects (loads, water, soil) to the horizontal stress distribution along the combined sheet pile wall and calculated the reaction forces using a set of boundary conditions. Within D-Sheet Piling the relieving platform was modelled by removing it, the loads that acted on it, and the soil that rested on it. The last method that was applied was a FEM software (Plaxis 2D). The FEM models were validated in three steps: First, by comparing their results to that of the conventional methods, it was found that the results of the conventional methods were within ca. 30% of the FEM results. Second, by comparing the results to actual field data, here the results showed both deviation and similarities, these deviations could however be explained. Lastly, by critically assessing the models to ensure that certain aspects were incorporated into the models correctly, this resulted in uncertainty about drained or undrained soil conditions for the thicker clay layers. The main function of both quay structures was the storage of certain goods, for that reason the only aspect that was not constant in the test loading set up was the magnitude of the primary surcharge. Both geotechnical and structural failure were taken into consideration for the quay structures. The results of the FEM models showed that neither of the structures had failed at their design loading conditions. For the Amazonehaven it was found that the magnitude of the primary surcharge at the first failure of the model was relatively close to that of the design loading conditions, it was incited by the exceedance of the geotechnical bearing capacity of the M.V.-piles. The first failure of the SIF model occurred at a surcharge that was more than 4 times the magnitude of the design loading conditions, it was incited by the exceedance of the normal stress capacity of the M.V.-piles.

As a result of population growth and economical prosperity, energy consumption has been on the rise for decades. Present-day projections predict the continuation of this trend with the rapid industrialization of former second world countries. Together with the rise of energy demand, incentives fo the scientific community to quantify the environmental impact of the ever increasing need for energy have gained momentum. It now is clear that continued use of carbon-based energy sources will have a catastrophic, irreversible impact on the global climate. The urgency of this message, which is supported by nearly the entire scientific community, was finally heard in 2012 when the Paris Agreement was drafted. Nearly collectively, the world’s countries are committing themselves to start the transition to durable sources of energy. One of the most promising sources of energy to facilitate the aforementioned transition, is the wind. Europe specifically is home to large patches of sea, which are ideally suited for the construction of offshore wind farms. Due to high construction costs, these endeavors out at sea were, until recently, heavily dependent of governmental support. However, due to advances in technology, wind frams have become profitable enough to be realized without governmental grands. Of the current offshore wind farms, the majority of the budget is allocated to the foundation design, construction and ultimately installation. Monopiles are convincingly the most common foundation type found. Although alternatives under development, it is unlikely for the popularity of this simplistic foundation will diminish in the near future. Especially, as the hollow, large diameter, hollow, steel profiles are finding their way into other foundations types, in example tripods. The installation of the monopiles offshore is mostly done through costly operations involving large hydraulic hammers. Prior to installation, drivability analyses are commissioned which determine the required hammer capacity. The rather simplistic software (in terms of soil representation) used to conduct these calculations, offers limited room for the optimization of the installation process. On the other hand, several full scale experiments have demonstrated that clever manipulation of driving parameters, specifically: (I) hammer weight; (II) driving frequency; (III) falling height/impact velocity; can significantly benefit installation times. This leaves a huge potential for cost savings (several millions EUR) per farm and forms a prime opportunity to stimulate the transition of offshore wind energy towards the mainstream. However, no consensus has been reached on the dynamic processes which positively contribute to the drivability of monopiles, let alone how these processes can be consciously induced in the subsoil. This research sets out to, by means of a parametric experimental study in the centrifuge, evaluate the effects of changes in driving parameters on driving time. Three hypothesis has have been drafted in an attempt to explain the higher efficiency piling operations employing HiLO (high frequency, low falling height) techniques instead of conventional driving, namely: (I) aggravated friction fatigue along the shaft due to an increased number of load cycles as a result of frequency increase; (II) Less dynamic soil resistance following from lower impact velocities, yielding the more efficient usage of available piling energy; (III) accumulation of excess pore water pressures, which reduce the effective stress regime surrounding the pile and thereby benefit piling rates. Through 24 centrifuge experiments, the aforementioned hypotheses are evaluated. During the experiments the effect of changes in driving parameters in monitored. Moreover, water pressure sensors mounted both on the pile shaft and inside the surrounding soil body record the soil response during driving. Results indicate that the dynamic installation of open-ended tubular piles in sandy soil, characterized by a high Rd (¼80%), is associated with the development of excess pore water pressures at larger radial distances from the pile due propagation of seismic waves. However, unlike similar experiments of samples with a lower Rd , the generated excess pore fluid pressures are limited in their magnitude as the soil exhibits no contraction to aid further generation. Moreover, closer to the pile, a transition towards a dilative soil regime is observed, where the increase of driving frequency is arguably related to the accumulation of tensile pore fluid pressures along the shaft, which negatively affects pile drivability. Results indicate the aforementioned adverse effect is partially compensated through the use of a heavy hammer due to subtle difference in soil-structure interaction related to the different geometry of the hammer. Consequently, it seems that HiLo driving is not a technique which guarantees better drivability under all circumstances. Hence, in the quest for optimum drivability, the prevailing soil conditions should play a decisive role in the selection of the best suited pile-hammer combination and driving technique.

Significant development of Jakarta infrastructure is necessary to keep up with the economic growth. For the new Jakarta underground rail network, imminent extension of the North-South Line Phase 1 (NSL-P1) tunnel heads towards the northern part of city. One of the engineering challenges that exist in the area is the substantial amount of reported surface settlement over the years, which is indicated by the continuous sea wall improvement project and the increase of flooded area. The recent GPS survey reported an average subsidence rate of 5 centimeters per year and could reach a maximum of 15 centimeters per year on several hotspots in North Jakarta. Being an underground structure, the rail tunnel would be affected by the settling environment and the reciprocity can be expected. Operational interruptions of the tunnel could occur in the future as a product of differential structural displacement. On the other hand, alterations in settlement rate or pattern must also be anticipated. The aforementioned reciprocity underlines the importance of structural and geotechnical assessments in the area. The assessment then can be used as a reference to determine and improve the safety level of the tunnel as well as the surrounding infrastructures. The study was commenced with the investigation of prevalent driving factors of Jakarta land subsidence from the preceding researches. The initial stage of the study elaborated the concepts used in the analysis, including geotechnical data interpretation, soil consolidation and creep, numerical model formulation, and past studies regarding the loads on bored tunnels. A segment of proposed North-South Line Phase 2 (NSL-P2) tunnel was selected for this study. The selection was motivated by the the amount of available geotechnical information and the severity of differential land subsidence in the respective area. Longitudinal and cross-sectional two-dimensional numerical model of the selected segment were developed in Plaxis 2D, based on the combination of in-situ soil tests and the outcome of earlier studies about Jakarta geotechnical characteristics. Into the model, four time-dependent groundwater level scenarios were assigned to simulate the surface settlement. As the research emphasizes on the long-term settlement, a 100-year study period was chosen and started in the year 2000. Given that the NSL-P2 tunnel design has not been confirmed at the time of writing, the numerical study adopted an identical design to the NSL-P1 tunnel. A 6.65-m diameter concrete tunnel was added into the model at an average depth of 15-m. From the longitudinal numerical analysis, total structural displacement in time and additional longitudinal forces were obtained. Subsequently, further analysis was performed on the cross-section, in the transverse direction, which displayed most settlement at the end of the analysis period. At the cross-sectional perspective, the development of forces as well as soil stress around the tunnel ring due to settlement and structural deformation were acquired. Finally, this study reached a general conclusion which explains that the land subsidence in Jakarta posed non-governing additional loads to the future NSL-P2 tunnel. A majority of the total surface settlement was caused by the consolidation and compression of the upper soil layers. However, special attention must be paid to the station-tunnel interface as substantial differential settlement could take place. To minimize further issues, several design recommendations are provided at the end of the research.

During construction in urban areas often noise and vibrations are not tolerated. For the installation of the foundation piles in these cases there is often chosen for screwed displacement piles. These piles can be installed without nuisance for the vicinity, but do induce large soil displacements during installation. The soil displacements can cause increased soil pressure on adjacent structures. Because urban areas are getting more densely built, these problems will occur more often in the future. The effects can be minimilized when they are known in advanced. This research looks into the possibility of predicting the installation effects of screwed displacements piles on adjacent structures. This is divided in the prediction of the soil displacement in a finite element analysis and in the effect of the soil displacement on adjacent piles. This is done with two case studies. First data from tests in Shanghai is used to create a finite element model. After this measurements are done in Rotterdam to verify this model for Dutch cases. Combining all the analysis of the measured and modelled displacements showed that the displacement is depended on the stiffness of the soil layers, the initial displacement at the edge of the pile and the distance from the pile. The soil parameters influence the initial displacements in each soil layers. When the initial displacements are correctly determined with tests, it is possible to predict the soil displacement due to the installation of a screw pile with a finite element model. No conclusion could be made on the effect of the soil displacements on adjacent structures.

TheNetherlands is a densely populated country and is located in an areawhere the shallowsubsurfacemainly consists ofHolocene and Pleistocene soils. To build permanent structures, enough bearing capacity is needed to provide sufficient support for these structures. However, Holocene (soft) soils typically do not provide sufficient support. In the western part of the country, the soft soils from the Holocene overlay the stiffer Pleistocene soils. To still be able to construct at locations where soft soils are found, pile foundations are needed to transfer the loads through the soft soil onto the stiff soil in order to provide for sufficient bearing capacity. The normativemethod for determining pile bearing capacity in the Netherlands uses a relatively straightforward semi-empirical approach known as the 4D/8D or the Dutch method. This method was based on the work of [vanMierlo and Koppejan, 1952] who introduce the logarithmic spiral theory. Apart from small modifications and elaborations, the method has been used ever since. To get to a reasoned solution on how to calculate and design pile foundations the Eurocode [Normcommissie 351 006 ’Geotechniek’, 2017a] was introduced. One of the (original) aims of the Eurocode was to harmonise rules and regulations regarding, amongst others, pile foundations. To prepare this harmonisation, Belgium, France and the Netherlands took a closer look into their calculation methods. For the Netherlands this research was performed by a committee who presented their findings in CUR 229 - “Axiaal belaste palen” [CUR B&I, 2010]. From CUR 229 it was found the pile tip capacity was overestimated. In other words, the calculated pile tip capacity was higher than the measured pile tip capacity. This overestimation led to a reduction of ®p of 30% starting on the 1st of January 2017. (®p is the factor which reduces the pile tip resistance for different pile types, see Appendix A.) A point of interest is the overestimation of the pile tip capacity, which seems to become more prominent when the pile goes deeper into a non-cohesive soil. It was even found, a lower ®p is not required for piles installed less than 8D into the bearing layer. The reduction of ®p seems to contradict with practice, because no cases of damage are known regarding the bearing capacity of pile foundations. Several explanations for this might be valid. For example, hidden safeties may prevent overall safety issues to arise. In addition, errors may occur in the determination of the pile capacity from pile load tests or in the Dutch method for calculating pile tip capacity. This leads to the two main subjects for this thesis. On the one hand, the hidden mechanism of residual loads is considered and on the other hand, the zone of influence at the pile tip during failure is analysed. To analyse the above-named subjects, the 4D/8D method was put under scrutiny. First, it was compared to other (international) analytical methods, which determine the bearing capacity directly from CPT data. Furthermore, the zone of influence around the pile tip is considered inmore detail by analysing the analytical approach and comparing this to the results of numerical models. This led to the conclusion that the observed overestimation can partly be explained by the inaccuracy of the assumed zone of influence around the pile tip, especially regarding the extent of this zone above the pile tip (8D). As this extent is too large, the 4D/8D method results in a too low average cone resistance in the 8D zone (for piles installed less than 8D into the bearing soil layer). In combination with the ‘old’ ®p , this leads to a reasonably accurate estimation of the pile tip capacity compared to the measured tip capacity. However, the observed extent of the zone of influence above the pile tip, in the FEMmodels, is in the order of 1 to 1.5D. The average cone resistance in this zone will in most cases be higher than in a zone extending 8D above the pile tip. The hidden mechanism of residual loads is implemented in a numerical model, with the use of a static load on top of the pile. The residual loads are caused by the installation of the pile and so, they are considered to be installation effects. No analytical or numerical models or procedures were found in literature to quantify the xiii xiv 0. Abstract residual load. Residual loads were implemented using a procedure defined in this thesis, taking into account the maximum pile tip capacity as indicator for the order of magnitude for the residual load. This is done, because a drawback of FEM models is; they are not able to calculate large strains, which occur during installation of a pile. Therefore the installations effects (like residual loads) have to be implemented indirectly. The horizontal compression due to installation is modelled as an installation effect according to the procedure of [Broere and van Tol, 2006]. Both installation effects are validated using data from CUR 229 and they are subjected to a sensitivity analysis. Furthermore, the softening or peak behaviour of soils might have a significant influence on the zone of influence around the pile and on the residual loads, as for both cases, the soil is loaded up to failure. Most regular constitutive models do not take into account this behaviour. Due to the fact the Hypo Plasticity (HP) model takes into account this peak behaviour, it was used to performthe FEM analysis. During the final stages of this thesis, scaled pile load tests were performed. The results of these tests were analysed to find the presence and order of magnitude of the residual load in a pile. However, as the test results were incomplete, only first assumptions were made that indicated the presence of residual loads. No substantiated conclusion could be drawn regarding the magnitude. Due to the observed importance of residual loads in this thesis, the residual loads should be measured during load tests more extensively using Osterberg cells or fibre optics. The installation effects are modelled in the Hypo Plasticity model with reasonable confidence, but future research is needed on models that can model the installation process (for example theMaterial PointMethod). Furthermore, the small strain parameters of the HP model should be taken into account. This thesis questions the 4D/8D method and shows some of its inaccuracies. However, more extensive research should be done considering the extent of the zone of influence and the limiting value defined by in the Dutchmethod. Also, the interaction between the shaft and the pile tip resistance has to be evaluated, as this thesis indicates they interfere with each other if the Dutch method is considered. Besides the zone of influence and the residual loads, the failure criterion stated by NEN 9997-1 is questioned. Failure of a pile happens when the pile tip has moved 10%D [Normcommissie 351 006 ’Geotechniek’, 2017a], but the FEM models show more displacements at failure, where failure is defined by themoment the models cannot stabilise anymore and therefore fail to calculate for a certain load step.

Almost 4000 MV piles are used as anchorage of quay walls in the port of Rotterdam. The current design method of MV piles in Dutch practice is a CPT-based method that correlates the cone resistance to the shaft friction by a factor α_t. In the port of Rotterdam, the cone resistance is restricted under the assumption that no shaft resistance higher than 250 kPa is mobilised. Consequently, α_t is used in combination with a limiting value for the cone resistance of 18 MPa. Moreover, the value of α_t that is currently used in the port of Rotterdam (1.4%) is derived after limiting the cone resistance at 18 MPa. Since this design method was developed in the 1980s', many more MV piles were tested in the port of Rotterdam. The maximum test load was generally at least two times the characteristic value of the required anchor force. None of these full-scale tests were loaded up to failure and no significant creep effects were observed. Consequently, the design standard was never updated as ultimate bearing capacity remained undetermined. Recently, the Port of Rotterdam has executed failure load tests in the Maasvlakte area. The tests allowed detailed strain readings along the full length of the test piles and offer the possibility to accurately determine the local mobilisation of shaft friction in addition to the ultimate failure load. Apart from describing the successful instrumentation with BOTDA fiber optical sensors (Brillouin Optical Time Domain Analysis), this study addresses the assessment of the obtained data in detail. Multiple relations are considered in this thesis. Analysis of CPT's indicates an increase in cone resistance due to pile installation. Investigation of pile driving data shows that installation energy correlates well with the cone resistance. Soil-structure interaction is analysed and a mobilisation curve is composed. This curve illustrates that mobilisation of shaft friction as a function of displacement of MV (tension) piles is similar to the Dutch standard for small and non-displacement compression piles. This thesis presents proof that limiting the cone resistance based on a maximum shaft friction of 250 kPa is not correct. The derivation of α_t without limiting the cone resistance results in a value of 1.2%. Installation energy proves to be a good indicator of the soil conditions. The piles that give good predictions for the bearing capacity with α_t = 1.2% present similar ratio's between the installation energy and the cone resistance. Future research may establish a consistent relation between CPT-based bearing capacity and pile driving energy to reduce uncertainty. This thesis will contribute to an update on the design method for MV-piles in dense sand layers of the Maasvlakte area.

Offshore wind turbines are commonly supported by monopile foundations. Impact hammering is the conventional method for installing offshore monopiles but has several disadvantages. Time-consuming installation procedures, high noise emissions and steel fatigue due to the high impact are problems resulting from this installation procedure. GBM Works is a start-up that is currently developing the Vibro-drill: a new method for installing monopiles, aiming to solve the stated problems associated with the hammering method. The Vibro-drill is mounted at the bottom of monopile and uses vibrating elements that simultaneously jet water, aiming to reduce the soil resistance. As a result, the monopile can penetrate the soil to target depth under its own weight. The monopile foundation is designed to support an offshore wind turbine throughout its lifetime of about 25 years. As the wind turbine is primarily subjected to lateral loads, one of the major design requirements is the stability of the pile in terms of lateral bearing capacity. Hammered piles have shown to provide sufficient lateral bearing capacity and this method has been used world-wide to install monopile foundations. Because the Vibro-drill machine is a unique and new concept, there is insufficient knowledge about the installation effects. Therefore, the lateral bearing capacity of a Vibro-drill installed pile is yet unknown. Before this new method can enter the offshore wind market, it needs to be researched and demonstrated that this new method provides sufficient bearing capacity for an offshore wind turbine. To that end, this thesis contains a study regarding the possible soil effects and resulting bearing capacity of Vibro-drill installed monopiles. Predictions of the monopile response were done with a finite element model in Plaxis 3D. The numerical model was verified based on data from monopile tests in Cuxhaven from 2014. During these full-scale field tests, three pile pairs were installed in dense sand by vibro-driving and hammering. The effect of the methods was quantified by lateral load tests on both piles. The input parameters for the Plaxis model were derived from CPT measurements using empirical relations based on relative density recommended for monopile design. The FEM predictions show a fit with the field-measurements during initial loading where after the curves start to deviate. The differences between the FEM prediction and the field measurements are discussed, expected is that they are caused by creep effects that occur in the field. As no soil effects as result from Vibro-drill installation have yet been measured, a worst-case approach was taken to identify the risks concerning the lateral bearing capacity. A hypothetic soil disturbance as result of Vibro-drill installation was generated based on studies regarding soil effect due to existing vibrating and jetting methods. Different worst-case scenarios of possible soil effects were sketched to study the resulting pile reaction due to a horizontal applied load. This was done by comparing the monopile response of a hammered and vibro-drill installed pile and increasing the pile size of the Vibro-drilled pile iteratively until a similar reaction to the hammered pile was obtained. In this way, the effect of a Vibro-drill installation was quantified in terms of additional pile material. For the studied scenarios, an additional proportion ranging from 17% to 29% of the embedded pile material was required to compensate for the softer pile reaction. Also, a study on the effect of pile size has shown that for larger piles, a lower proportion of additional pile material is required to compensate for a possible softer pile response resulting from Vibro-drill installation.

This thesis investigates the behavior of single and group micro piles under axial tensile loading. Micro piles are small diameter piles consist of grout and steel rebar and they are capable of absorbing tensile loads. By constructing a group of piles the bearing capacity of each pile within a group is less compared to the single pile. The reason is due to the existence of group effect in the pile group which influences the bearing capacity. During the production of the piles for Amsterdam car parking project, load tests are performed to check whether the piles behave according as expected which can be considered as acceptance tests. However in this test, only individual piles are tested and not a pile group. CUR 236 design procedure states that the bearing capacity of a pile in a pile group is less than the bearing capacity of that pile when it is loaded not in a group. To take this effect into account for the acceptance test, an additional load is added to the test load. It turned out at the Amsterdam car parking project that piles failed the acceptance tests due to this additional load which is required to apply according to CUR 236 design guide. However this procedure is questionable because the pile is loaded into a much higher level than it will actually experience during its lifetime. Therefore an evaluation of the standards and the influence of group effects on micro pile behavior is needed. The initial plan of approach was to investigate the standards of other countries and compare them to Dutch standards to find the eventual existing gap and propose an improvement method which did not succeed. The reason was that the standards of other countries were all written in their national language and therefore it was not possible to study them. Seeking for the research on tension pile group behavior did not help so much because many researchers believe that including a realistic group effect in the design is not an easy task and there was no clear conclusion on micro pile group influence. The direction of approach is then changed towards the numerical modelling and based on it the influence of group effects on micro pile behavior is presented. First a single micro pile is modelled with Finite Element Method in Plaxis. The single pile is finally modelled in plane strain by using Embedded Beam Row element. Model parameters and properties are defined based on Amsterdam case study. The load-displacement behavior of the single pile model was comparable with the one from Amsterdam field failure test and is therefore validated based on field failure test data. After development of single pile model, the model for pile groups is made. This group model is made to represent the practical situation in a building pit for Amsterdam case study. Three models for the pile group have been made which differ in pile spacing and the impact of this parameter on the capacity per micro pile is investigated. The different used pile spacings are 5D, 10D and 15D which are equal to 1 meter, 2 meters and 3 meters. Also for each pile spacing, the dominant failure mechanism is determined. According to the results it was concluded that for 5D and 10D pile spacing, the failure mechanism is based on soil plug pull-out while for 15D, it is according to slip failure. By validation of the pile group model, an improvement for the space between the piles within a pile group can be proposed as 10D where the soil plug pull-out is dominant failure mechanism. It is recommended to validate the pile group model based on full-scale failure test on pile groups or by small-scale test using Geo-centrifuge models. Also by monitoring, a real data base of the group behavior can be obtained. Comparing the monitoring data to the design values based on CUR 236 could give an idea how well the design guide is formulated.

Quay walls are often designed with Finite Element models (FE models) to take into account the complex soil-structure interaction and highly non-linear soil behaviour. These are complex models that rely on many input parameters that have uncertainties. Nowadays, new quay walls are often equipped with sensors that collect information about the behaviour of the quay wall. These quay walls are known as extbf{smart} quay walls. The measurement data of smart quay walls could be used to validate FE models and reduce parameter uncertainties. This could lead to an optimisation of the functionality of the quay walls. By means of a case study this thesis determines if measurement data obtained during the construction process has the potential to optimise the functionality of smart quay walls. The case used is the HES Hartel Tank Terminal (HHTT-quay), which is a smart quay wall in the port of Rotterdam. The HHTT-quay consists of sections with and without a relieving platform, both are considered in this thesis. In this thesis the functionality of a quay wall refers to the retaining or bearing functionality. Therefore, an optimisation of the functionality could consist of an optimisation in the retaining height or the surface loads. The case study used in this thesis shows that measurement data obtained during the construction process already provides important information that can be used to optimise the functionality of the quay wall. This indicates that for smart quay walls the construction process can act as a load test and this could reduce the necessity to perform a load test during the service life.