To fight increasing traffic in city centres, tunnelling can be used to move traffic under the surface of the busy city. However, to prevent damage to the surrounding buildings, the settlements induced by the tunnelling should be kept to a minimum. This thesis researches the influence of the TBM tail void and its grouting process on the settlements. To do so, the monitoring and TBM data from the North/South line in Amsterdam is used. The data of the settlements, grout pressures and grout volumes is searched for locations with sudden changes. For these locations, the development of the settlements as a function of the TBM movement is compared to find out if the changes in settlements are caused by the tail void. This turns out to be the case for half of the researched locations. Furthermore, the changes of the grout pressuresmeasured in the tail void, and the volume injected grout volume are compared for these locations. An increase in injected grout volume shows to decrease the settlements induced by the tail void, while the pressure does not show a correlation with the settlements. Because only one sensor was used for the pressuremeasurements, the grout pressures are then compared for all sensors in the tail void. Again, no correlation is found between the grout pressures and the settlements. A side step in the research shows the development of the grout pressures in the tail void. During the boring process the grout pressures fluctuate. During the boring and forward movement of the TBM the tail void is injected with grout and the grout pressures in the tail void increase. During the ring building phase, this grouting stops and the grout pressures start to dissipate. The amount of dissipation is influenced by the permeability of the surrounding soil. With the help of DIANA FEM software, the influence of the tail void on the total settlements is investigated. The calculations show that a different grouting behaviour caused a change of only 4mmin total settlements. Concluding, as long as the pressures in the tail void stay above the soil pressure the tail void can be filled with grout. The injected grout volume will fill the tail void, preventing the soil from moving into the tail void and with that minimising the settlements at the surface.

This research has shed light on the capability of the HASP model in reproducing the dilatant behaviour of OC clays in drained and undrained conditions. The model is formulated by employing a combined hardening rule and uses the void ratio as a state variable while maintaining the simplicity of the MCC model. However, a sensitivity analysis has revealed that the model is sensitive to some input parameters which when varied slightly can largely affect the outcome of an analysis.

This has led to the formulation of the PLAXIS OC clay model while maintaining the framework of the HASP model but replacing the void ratio with volumetric strain as the state variable. Thus resulting in the use of the modified compression (λ*) and swelling (κ*) indexes which are used in obtaining the soil stiffness parameters used as model inputs. The PLAXIS OC clay model features the use of real soil stiffness parameters instead of soil indexes, the addition of small stain stiffness by T. Benz to improve model prediction in the small strain region and the elimination of the sensitivity issues noticed when using the HASP model.

The PLAXIS OC clay model is validated for boom clay (BC) at single stress points by simulating CU test and comparing with the available experimental data for the BC. Good agreement is found with experimental data as shown in the stress strain, pore water pressure and stress path plots obtained from the analysis.

Furthermore, the model is used to simulate boom clay in a trial excavation. Piezometers and extensometers are installed into the BC layer prior to the excavation to monitor the changes in porewater pressure and vertical displacement (heave) on the BC during the excavation. A comparison of the numerical and experimental data shows that good agreement is observed in porewater pressures and vertical displacement in the BC layer.

The widely used cone penetration test (CPT) allows in-situ measurements of soil behaviour during continuous penetration. The traditional sensors incorporated in a cone penetrometer are for measuring cone resistance, sleeve friction, pore pressure, and inclination. Many supplementary sensors have been studied and tried in research settings and in practice. Examples are sensors for natural gamma radiation, electrical resistivity and time domain reflectometry. None have made it to routine practice. As an introduction to the thermal cone penetration test, this thesis presents a review of CPT add-on sensors that (1) allow continuous penetration at 20 mm/s, (2) considered robust, i.e. have no external moving parts, (3) offer potential for broad geotechnical value, i.e. not limited to special applications only. The review considers recent advances in electronics, sensor technology, and data processing systems. The Thermal Cone Penetration test (T-CPT) was introduced by Akrouch (2016) using temperature decay test to determine the soil thermal conductivity. An improved interpretation model was proposed by Vardon (2018) and validated via an in-situ testing programme (Vardon et al., 2018). The T-CPT records temperature variations during continuous penetration depending on different factors such as soil type (grain size), soil strength, and thermal properties of soils. In this report, the potentials of the thermal cone penetration test prototype developed and used by Fugro are investigated during continuous penetration conditions in order to determine the possible dependencies between the soil engineering properties and the T-CPT measurements.

A series of finite element simulations via PLAXIS were carried out to investigate the effects of micro- tunnelling on nearby pile foundations. A numerical model concerning the large diameter tunnel boring machine was first established based on identical properties of the centrifuge experiment executed by Loganathan et al. (2000). Results from numerical simulation were validated by measured data from the centrifuge test. After the validation of the numerical modelling method, the model was adjusted to match the case of micro-tunnel and a new model regarding the micro-tunnelling procedure was generated based on geotechnical conditions of the North/South Metro Line Amsterdam. The Hardening Soil constitutive model was chosen for all soil layers. In the model, the condition of single bored pile with working load was activated in the greenfield condition before the simulation of micro- tunnel. Advancement procedure of the micro-tunnel was simulated, and pile responses were collected under the plane strain condition. Based on the study of the model, two load transfer mechanisms of piles during tunnel-pile interaction process were identified. Impact of tunnel advancement on adjacent piles was also interpreted. A set of parametric studies were implemented to study changes of pile settlement and bearing capacity with increasing volume loss. An influence zone around the micro- tunnel respecting the potential of pile critical movements was established. Although the lack of field data makes the validation of results hard, comparison with analytical prediction and measured data from the centrifuge test shows good agreements for soil movements and pile responses. The results of this research remain to be validated by field data but it can provide insights into the problem of the impact of micro-tunnelling on piles.

The subsurface is often modelled as multiple homogeneous soil layers. In reality, the soil properties of these layers are heterogeneous and spatially variable, making it difficult to properly deduct the engineering properties that are required in the design of geotechnical structures. This leads to uncertainty in the design. The probabilistic framework known as the random finite element method (RFEM) can take the spatial variability of soil properties into account in geotechnical designs in an effort to reduce the uncertainty. The spatial variability is represented by the mean, the standard deviation and the scale of fluctuation. The scale of fluctuation is defined as the distance in which a significant correlation is found within the soil properties and is related to the geological deposition of the soil layer. The calculated reliability of man-made structures, such as dykes, is the output of the RFEM and is influenced by the scales of fluctuation of the subsurface. Since many man-made structures in the Netherlands are constructed on soft soils, they cause deformations in the subsurface. These deformations change the geological layering of the soil. It is therefore expected that the deformations caused by man-made structures influence the scales of fluctuation and that the changed scales of fluctuation influence the calculated reliability of the man-made structures. The objective of this thesis is to research how the spatial variability of soft soils is influenced by man-made structures. To research this, a case study is undertaken at the Leendert de Boerspolder in the Netherlands. One-hundred cone penetration tests (CPTs) have been taken in an area of 15 by 50 meters in the polder as well as in the dyke as part of the research programme Reliable Dykes. From the cone resistance data of the CPTs the spatial variability of the area can be estimated. The case study is accompanied by two theoretical studies. The first study aims to estimate the effect of deformations on the spatial variability of generated random field data for different types of deformations. The second study of this thesis will provide the deformations that have occurred in the area of the case study from a plane-strain finite element analysis of the dyke and polder.
The first part of the research focussed on four deformations that are often encountered in the proximity of a dyke: vertical compression, horizontal compression, simple shear and rotation. The effect of these deformations on the spatial variability has been studied by applying the deformations to three resolutions of random fields and then estimating the change in scales of fluctuation. Since no soil properties were assigned to the random fields, the results can only be used qualitatively. The research is then continued with the estimation of the spatial variability of the Leendert de Boerspolder. It was necessary to identify the soil layers first. These are a top peat layer, a clay layer which shows a transition from organic at the top to silty at the bottom, and a bottom peat layer. For each of the CPT lines parallel to the dyke the outliers of the cone resistance data were removed for the different soil layers and the depth trends were removed. This resulted in normalised cone resistance data from which the spatial variability in different directions could be estimated. Finally, a two-dimensional plane strain analysis of the soil layers at the Leendert de Boerspolder was made. In the first step of the analysis the depths of the soil layers are at the level before construction of the dyke. Then the dyke was constructed step-wise. This allowed the initial soil layers to deform as close as possible to the actual deformations under influence of the dyke. Finally, the following conclusions are made by combining the resulting deformations with the results of the other research. At the Leendert de Boerspolder, the spatial variability of the polder next to the dyke is not influenced by the dyke and can be used as the baseline spatial variability to which to compare the spatial variability in the proximity of the dyke. Underneath the crest a significant vertical compression causes both the vertical and horizontal scales of fluctuation to decrease, while a smaller amount causes a change in just the vertical scale of fluctuation. Underneath the slope and toe of the dyke, rotation increases the larger vertical scale of fluctuation and decreases the larger horizontal scale of fluctuation. Horizontal extension of the soft soil underneath the slope results in a larger horizontal scale of fluctuation. Horizontal compression underneath the toe results in a smaller horizontal scale of fluctuation.

A new trend to found offshore wind turbines at larger depths or on harder soils is to apply gravity based foundations (GBFs). These foundations are caissons with a set of properties which are different with respect to other caisson types. The number of constructed caissons is large and the timeframe for construction and transportation from land into water is small when these foundations are applied on commercially scaled offshore windfarms. In general, an offshore wind farm is constructed within two years and all GBFs must be constructed and transported into the water in a tight time schedule.

To accomplish the construction and installation of a large number GBFs in a tight timeframe, a new design method is developed. A realistic case study is composed and the target is to construct and install 64 GBFs in front of the Belgium coast in a timeframe of 2 years.
Two designs are considered, a materialefficient design and a design which is optimized regarding the constructability.

When the GBF-design is known, the transportation method from land into water is considered. According to the decision matrix, developed in the literature study, the only feasible method is to apply a semi-submersible vessel. However this solution is quite expensive, whether the storage location is at the construction area or in the sea. Due to the large costs a new alternative method could be feasible. Several new ideas are created and the most promising solution is ‘The immersion structure’.

Because time is the most important factor, the construction planning and construction area layout are considered. Three options are considered and the most optimal construction planning is chosen. On four locations the construction activities are optimized and with the use of a production line it is possible to construct the 64 GBFs in time with minimal use of area and equipment. Because of the small area left, the storage location cannot be designed on the construction area.

The design of the immersion structure consists of a platform which consists of H-beams and two concrete hollow legs. The immersion structure is innovative because it is placed directly on sand and no foundation works are needed. Due to the large capacity the main part of the caisson types can be transported. Because the structure is able to float it can be easily transported.

At last the construction and operational costs of the immersion structure are compared with the cost of renting a semi-submersible vessel. The semi-submersible vessel seems to be the best solution but when the immersion structure is applied at multiple projects it could be a profitable solution. The depreciation and interest costs for the immersion structure are calculated and the immersion structure is profitable when a minimal utilization rate of 22% is achieved during a service lifetime of 20 years. Depending on the market development and the amount of applicable caisson construction projects the immersion structure could be profitable. Comparing with the case study the immersion structure is profitable if three comparable projects are executed in the service lifetime.

The introduction of the new 'Waterwet' led to the retesting of a lot of primary flood defences within the Netherlands, sequentially certifying a lot of levees as unsafe regarding inner slope stability. To test or design a levee an adequate amount of soil investigation is required to indicate the presence of different soil types, stratification and to estimate the relevant soil parameters. The spatial spreading and the fact that the number of cone penetration tests (CPT) and boreholes within a levee to determine geotechnical parameters and stratification are limited, means that the estimated parameters always contain uncertainties. Nevertheless current guidelines do not cover the minimum CPT interval size or the uncertainty in undrained shear strength in longitudinal direction. In this thesis it is analysed how the quantity of CPTs in longitudinal direction affect the estimated undrained shear strength, and how this influences the probability of failure regarding inner slope stability.

A 5 km long levee containing a continuous peat and clay layer along the Markermeer is specified as research area. In this area the CPT interval size in longitudinal direction is 100 m. The inner slope stability is analysed with D-Geo Stability (level I reliability approach) and the Probabilistic Toolkit (level II reliability approach). Although simplifications within the model ensure that only layer thickness and undrained shear strength vary in longitudinal direction, the calculated safety factors still show a lot of fluctuation. The probabilistic stability analysis show that in the considered research area, the undrained shear strength has a larger influence on the probability of failure in comparison to layer thickness, unit weight and outside water level.

As the CPT interval size increases in longitudinal direction, the minimum safety factor could be overseen, which can lead to optimistic reliability estimations. The theory of information entropy is used to analyse the effect of changing CPT interval sizes on the estimation of the undrained shear strength. Information entropy measures the amount of uncertainty/information in a dataset. A new partial factor (the ‘spatial factor’) is proposed based on the normalized entropy. The proposed spatial factor accounts for spatial uncertainty in the estimated undrained shear strength in longitudinal direction and assigns additional safety when the CPT interval size is larger than 100 m for the considered research area. This methodology promotes the collection of additional data, which is thought to be the basic starting point for any partial factor that is assigned to cover epistemic uncertainties.

In 2009 and 2010, two leakages through immersion joints occurred in the First Coen Tunnel near Amsterdam. From the study on t-he cause of these leakages, it followed that there was a potential problem for existing immersed tunnels: failure of the temporary Gina-seal combined with corrosion on the clamping structure of the definitive Omega-seal. It is unknown whether the immersion joints of existing immersed tunnels in the Netherlands will still function during the remaining design lifetime. There is lack of calculations on the governing watertight parts (Gina-seal and Omega-seal) in immersion joints. The main goal of this research is to become both qualitative and quantitative insight into the watertightness of existing Gina-seals and Omega-seals in immersed tunnels. It is applied to the Kil Tunnel (case study).

Leakage through immersion joints can only take place when both the Gina-seal and the Omega-seal fail. The Gina-seal consists of a rubber gasket (the Gina-gasket) and a clamping structure that connects the Gina-gasket with the tunnel element. It can fail due to widening of the joint (due to seasonal temperature changes) combined with relaxa-tion, increased soil pressure and differential movements of the tunnel elements. The Omega-seal consists of a rubber gasket (the Omega-gasket) and a structure that connects the flange of the Omega-gasket with both tunnel elements (the clamping structure). It can fail if the clamping structure is affected by differential movements, relaxation, corrosion and widening of the joint (due to seasonal temperature changes).

The Kil Tunnel (case study, finished in 1977, below Dordtsche Kil) consists of 3 tunnel elements, so it has 3 immersion joints (1A, 2E and 3A). Immersion joint 1A and 2E connect the tunnel to both abutments and are exactly the same. Immersion joint 3A connects two tunnel elements to each other. The Gina-seal and the Omega-seal are slightly different for 1A/2E and 3A.

The Gina-seal has to meet several requirements in order to be watertight. The result of the case study on the Gina-seal in the Kil Tunnel is the following:
- Joint 1A/2E may not meet Requirement G2 roof (Force equilibrium in the roof). This check requires attention. Therefore, it is recommended to do visual inspections in the roof of joint 1A/2E. All the other requirements are met with large margins.
- Joint 3A meets all requirements with large margins. It is expected that this Gina-seal fulfils its function over the entire lifetime.
- It is recommended to measure the value of maximum difference between winter and summer of the immersion joint in longitudinal direction (Δx) in all immersion joints.

The Omega-seal has to meet several requirements in order to be watertight. The result of the case study on the Omega-seal in the Kil Tunnel is the following:
- The compression of the flange of the Omega-gasket (cO) determines strongly whether the requirements on watertightness are met. When the compression of the flange of the Omega-gasket is smaller than 5 mm, the requirements are not met. This means that leakages through the immersion joint can occur. It is recommended to measure this value.
- The maximum allowed penetration depth of the corrosion is 2 mm of the core of the bolt. If this value is exceeded, the functioning of the bolt is not guaranteed anymore. It is recommended to remove a bolt at the “splash zone” in order to see how far the corrosion has penetrated the bolt. Besides, it must be checked whether the corrosion is an on-going process.
- When one bolt fails, the clamping plate will deform. As a result the forces on the adjacent bolts will be lower. It depends on the state of the bolt whether this is able to take the loads. This will determine whether the ‘zipper effect’ will occur.

This study has created a theoretical description of the state of existing Gina-seals and Omega-seals. However, visual inspections and measurements are also needed to judge whether the seals will function during the remaining lifetime.

PLAXIS study of a primary flood defence in the Netherlands. The influence of water level, precipitation, and wave overtopping on the position of the phreatic surface is being investigated. The hydraulic loads are applied to a clay dike with a cracked top layer and a sand dike with a cracked clay cover. The findings are related to the current deterministic methods to estimate the location of the phreatic surface.

The use of geotextile for slope strengthening was proven based on the investigation and report by Kuwano, Miyata, and Koseki (2014). Therefore, this research examines the impact of geotextile application on slope stability in newly-elevated area in Yuriage, Natori City, Japan. This project discussed the analysis of geotextile-reinforced slope by comparing the total displacement at the crest of slope between the compaction method as current design and the using of geotextile with further investigation by optimising the use of geotextile application.
A cross-section of slope with 0.435m height and 29 degrees slope angle were chosen for the geometry of analysis. Two loads acted on the slope such as the uniform load on top of the raised area and dynamic load from the earthquake were defined. Six layers that mostly consist of sandy soils were determined based on the SPT data in 16 locations. The average values of N-SPT were calculated for further parameter correlations based on these values. Furthermore, analyses based on the Limit Equilibrium method and Finite Element Method were selected to analyse the slope stability.
Limit Equilibrium Method using D-Geo stability software based on the Bishop method was taken to define safety factor of slope under uniform load (without earthquake load). The value of safety factor at 1.93 was obtained then compared to the result for the same problem based on the Finite Element Method using PLAXIS 2D with HS Small model that resulted at 2.07 safety factor. Further dynamic analysis was also completed using PLAXIS 2D with UBCSAND model to calculate the total displacement at slope crest without and with geotextile application. The strengthening method using geotextile (500 kN/m tensile strength, 5004 kN/m axial stiffness, 30m length in 5 layers) decreased the total displacement from 0.543m to 0.434m. However, the impact of geotextile is very limited in this case that only decrease 0.109m or about 20% from the total displacement without geotextile. Weak foundation, silty clayey sand layer (AC1) and liquefied layers (AC1 and fine sand AS22) below the slope were observed as the main reasons for this small impact of geotextile. Therefore, geotextile method is not recommended to use in this project given its very limited impact on the total displacement. Furthermore, the soil improvement methods were proposed to tackle these two reasons, such as replacing the soil material (AC1) with stronger soil for the foundation under the slope and/or construct sand pile to minimize the liquefied layer below the slope until AS21 depth, about 6 meters.
Further analysis based on combination of five values of geotextile strengths, four difference lengths, and three number of layers were made to get the optimum used of geotextile by comparing the total displacement at the crest. The first factor that has to be considered is the strength of geotextile because this factor gives more influence in the final total displacement. Secondly, with the high strength of geotextile, the length should be considered first rather than the number of layers based on the impact of both factor on the influence of strength to the total of displacement.

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.

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.

Due to increased traffic density, there is a tendency to construct larger immersed tunnels with larger tunnel elements both in transversal and longitudinal direction resulting in a more critical design of the joints. Especially for those tunnels with relatively soft foundation and high siltation, there is no mature experience for reference. This not only requires a more detailed analyze of the joint itself, but also of the total behavior of the tunnel and its interaction with the subsoil.
Conventional deterministic designing procedure is based on average soil characteristics with sensitivity analyses including upper and lower boundaries of soil stiffness. The mentioned above trend of larger structures requires a more sophisticated probabilistic approach with deeper understanding of uncertainties and insight in probability of exceedance of requirements in serviceability limit state.
In this paper, a probabilistic analysis approach has been implemented to understand the shear behavior of tunnel joints. The biggest contributor for tunnel joints shear behavior is differential settlement between adjacent parts of the tunnel structure. Two probabilistic methods, Point Estimate Method and Monte Carlo Simulation are performed on settlement determination. The former is more efficient and with a considerable accuracy while, the latter is extremely accurate with high computational costs. For simple cases, Monte Carlo Simulations are commonly used to solve soil structure interaction problems due to its straightforward process and easily understandable theory. While for large and complex soil-structure interaction problem, it is computationally intensive to complete even a single run. Such practical disadvantage can be solved by modifying the algorithm or by performing computationally efficient probabilistic methods.
The soil-structure interaction analysis is researched by models set up in PLAXIS 2D. Python scripts are programmed in cooperation with PLAXIS models to perform Monte-Carlo Simulation in determination of shear forces in tunnel joints. The function of Python scripts is helping PLAXIS to select properties automatically and to storing the output after every single run.
The reliability analysis is done for different conditions in 3 models. Comparison shows that reliability significantly influenced by the distribution and correlation length of soil parameters.

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.