bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction and Back-Analysis of Centrifuge Lateral Pile Load Tests in Fine-Grained Soil
Authors: Zhang Y , Gaunt P , Gundersen A S , Sivasithamparam N , Engin H K
Published: June 2024

The performance of offshore pile foundations under lateral loading is an important topic in offshore geotechnics. In connection with the 3rd International Symposium on Frontiers in Offshore Geotechnics, an international prediction event on laterally loaded pile foundation in fine grained soil was organized by the University of Western Australia. The soil characterization results and test set-up for four centrifuge pile load tests were provided to participants who were asked to predict the pile responses. The testing program included one monotonic pushover test, two displacement-controlled cyclic tests and one load-controlled cyclic test. The authors participated in this prediction event using both p-y based approaches and finite element analyses. The purpose of this paper is to present the methodologies and review the selection of parameters used for the original predictions and back-analysis of the centrifuge tests. The performance of the prediction models is assessed based on the test results. The reconciliation between the model predictions and the measured results, and implications for practical design are discussed.
Automation of Slope Stability and Rockberm Support Design
Authors: Kay D , Panayides S
Published: June 2024

Field developments for energy generation may require infrastructure to cross continental shelf escarpments and/or channel features and canyons of variable soil conditions. This aspect frequently entails large seabed interventions to reduce spans and mitigate against product fatigue. The typical design process relies on thorough and accurate assessment of geophysical and geotechnical data to evaluate slope stability and potential hazardous areas along the seabed. This design engineering is multidisciplinary and is typically an iterative process requiring several analyses to be conducted in a short space of time. The final aim being to ensure cost effective and timely offshore seabed preparatory operations are safely completed prior to arrival of the installation vessel which is typically on the critical path for project completion. Process and design automation in engineering tasks has received a great amount of attention in recent years. With close engineering control and robust design workflows, this results in increased productivity to meet demanding project schedules whilst lowering cost. This paper describes the automated processes and geotechnical design for slope stability assessments with the full array of seabed intervention works of seabed excavation and subsea rock installation. The paper also highlights the efficiency of the new tool in comparison to previous analyses.
Numerical Model of a Large-Scale Monopile Test in Non-Cohesive Soil
Authors: Spill S , Lillie C , Collmann M
Published: June 2024

Accurate modelling of the pile-soil interaction for offshore support structures is a great challenge for the industry. A main influencing parameter is the installation technique and the effects to the surrounding soil. As the numerical modelling of a pile installation process is time consuming, piles are usually modelled numerically as wished-in-place structures. When using this modelling strategy, the initial soil parameters should be adapted, depending on the installation technique. Especially for offshore piles, there are currently no general approaches to consider these installation effects. In this contribution a brief summary regarding impact and vibratory driven installation and their influence on the lateral load-bearing behavior is given. Furthermore, experimental results as well as a hypoplastic numerical prediction of a large-scale impact driven monopile test are presented and their results are evaluated. Finally, conclusions about the consideration of installation effects when modeling the pile load bearing behavior are drawn.
Climate Change Effects on the Design of Spar Floating Offshore Wind Turbines
Authors: James M , Haldar S , Bhattacharya S
Published: June 2024

Global warming and climate change are the most alarming issues the world faces today. To confront these consequences, wind turbines are being constructed worldwide. However, the impact of climate change on the design of wind turbines has not been studied comprehensively. This study examines the performance-based design of spar-type floating offshore wind turbines supporting 5 MW, 10 MW, and 15 MW wind turbines by considering the future climate of the North Sea. A 5% reduction in the annual average wind speed is predicted. But the yearly average wind speed is still observed to be 9.1 m/sec, close to the rated wind speed, providing security for wind turbine investors. Compared to the historical period (1981 to 2010), significant wave height and wave period are forecasted to decrease by 11% and 8% during the design period. Consequently, after incorporating the future climate into the analysis, an overall reduction in the responses including acceleration, tower rotation, mooring tension, and bending moment at the tower base is observed. This paper provides a simplified methodology to consider the climate change effect in the design of floating wind turbine.
Time-History Effective-Stress Analyses of OWT Suction Bucket Foundation in Sand Under Sustained Tension Typhoon Loading
Authors: Tasiopoulou P , Limniaiou T , Chaloulos Y , Giannakou A , Chacko J
Published: June 2024

Suction buckets supporting a tripod jacket structure can be subjected to sustained tension loading during storm loading. The long-period content of the storm loading combined with its cyclic nature, can lead to partial drainage conditions where generation of excess pore pressure competes with dissipation during loading, resulting in complex response mechanisms. These mechanisms, associated with sand-like behavior, are rarely considered in design which are typically based on binary assumptions regarding drainage, fully undrained or fully drained, and unity checks comparing an estimated degraded capacity to peak storm loads. In this paper, numerical time-history, effective-stress, coupled-flow analyses of a single suction bucket under storm loading were performed in the finite-difference code FLAC3D. The irregular load time history applied corresponds to a 600-second window where the highest tension loads are observed. The Ta-Ger constitutive model was used for the cohesionless soils, calibrated against undrained CDSS tests. Sensitivity analyses on drainage conditions and model calibration parameters affecting the drained response showed that drainage effects are important for design optimisation. Moreover, it was shown that the sequence of the pulses within a time-history can have a significant impact on system deformations.
Geohazard or Geo-Engineering Constraint?
Authors: Dimmock P S , Riera R , Tam T A , Boylan N
Published: June 2024

There is varied interpretation of what constitutes a geohazard. This paper first explores use of the term, then proposes a more selective use of the term for the benefit of geo-engineering and geo-risk management activities on development projects. It is proposed to restrict the term 'geohazard' to dynamic processes that impact the development. Another term 'geo-engineering constraint' is proposed to cover pre-existing features, static in nature, that require engineering consideration. The benefit of creating this distinction is in the different project treatment of a dynamic process compared to engineering for an existing static feature. By this convention geohazards are characterised by risk frameworks (likelihood and consequence), such that the risk can be managed and mitigated. Geo-engineering constraints, on the other hand, can be directed towards, and addressed by, routine geo-engineering design processes. Examples are provided in the paper to demonstrate how this terminology is applied, and how geohazards are characterised in comparison to geo-engineering constraints.
Effect of Installation Parameters and Initial Soil Density on the Lateral Response of Vibratory-Driven Monopiles: A Laboratory Study
Authors: Peccin da Silva A , Post M , Elkadi A S K , Kementzetzidis E , Pisanò F
Published: June 2024

The vibratory installation of monopiles as foundation for offshore wind turbines is considered a plausible solution next to the conventional installation method (impact-hammering). One of the main advantages is the lower noise emissions, reducing harm to the marine life. However, knowledge on the effects of the vibratory installation parameters on the lateral response of monopiles - and how these effects differ from those caused by impact-driving - is limited. This paper presents the results from an ongoing Joint Industry Project (SIMOX) with focus on 1g laboratory tests carried out in a 9.0m x 5.5m x 2.5m tank with saturated sand at Deltares, the Netherlands. The tests involve the installation (impact and vibratory) of scaled piles with 32 cm diameter, embedment length of 1.5 m and two wall thicknesses. The lateral loading regime consisted of monotonic and cyclic lateral loading. The results show the effect of soil density and different installation parameters of vibratory installation on the lateral response of the piles compared to a conventional impact installation.
Improving Driveability Predictions for Offshore Piles Using Bayesian Optimisation
Authors: Buckley R , Chen Y M , Sheil B B , Suryasentana S K , Randolph M F , Doherty J P
Published: June 2024

Pile driveability predictions require information on the pile geometry, impact hammer and the soil resistance to driving (SRD). Current methods to predict SRD are based on databases of long slender piles and have been shown to provide poor predictions when applied to geometries outside of their original calibration spaces. New, robust and adaptable methods are required to predict SRD for current offshore pile geometries. An optimisation framework to update uncertain model parameters in existing axial static design methods to calibrate SRD is described. The optimisation is undertaken using a robust Bayesian approach to dynamically update uncertain variables during driving. The framework is demonstrated using a case study from a German offshore wind site. The static method is shown to perform well for piles with geometries that reflect the underlying database such that only minimal optimisation is required. For larger diameter piles, relative to the prior best estimate, optimised results are shown to provide significant improvements in the mean calculations, and associated variance, of pile driveability as more data is acquired. When compared with results determined using the conventional design approach used by industry, the optimised parameters provided notable improvements in the agreement between measured and calculated values. The optimised parameters can be used to predict SRD in similar profiles where large datasets are available, the demonstrated framework may be used to develop new SRD methods.
Foundation Response of a Jacked-Up Vessel Upon Earthquake-Induced Subsoil Liquefaction
Authors: Bertalot D , Ottonello L , Brinkman S , Soler D
Published: June 2024

This paper presents the outcomes of a parametric study commissioned by Van Oord Offshore Wind to improve the understanding of the potential consequences of subsoil liquefaction while operating their installation jack-up vessel in seismically active areas. The focus of this work is assessing the impact of the spudcan foundations (under operational loads) on the seismic response of an otherwise liquefiable (under free-field conditions) soil deposit, verifying whether the additional, large, overburden exerted by the spudcan, as well as the stress-history and possible densification of the foundation soil during pre-loading operations, may have a beneficial effect on the cyclic resistance of the foundation soils. A thorough calibration of the fully coupled soil constitutive models adopted was carried out against a comprehensive set of laboratory test results. The ability of the constitutive model to accurately predict earthquake induced liquefaction is further demonstrated by benchmarking against in-situ test based liquefaction assessment. The paper presents the outcomes of an extensive series of dynamic FE analyses, aiming to investigate the effects of several variables on the overall response of the system, including relative density of the liquefiable soil layer, thickness of liquefiable soil layer, earthquake motion characteristics, shaking intensity and operational load level.
Experimental Investigation on the Performance of Tolerably Mobile Subsea Foundations With Varied Interface Conditions
Authors: Liu J , Zhang X , Feng X , Han C
Published: June 2024

Tolerably mobile subsea foundations obey the 'compliant' design guidelines rather than the traditional approaches which require adequate geotechnical capacity to fix the foundations. When the connecting pipeline is heated up for operation or cooled in 'shut-down', the foundation is allowed to cyclically slide on the seabed to release the axial expansion or contraction force in the pipeline. It is necessary to determine the sliding resistance, vertical settlement and rotation of the foundation in order to derive optimised design solutions. The sliding resistance and the shear-induced settlement are greatly affected by the foundation-soil interface condition. This study conducted a series of model tests to investigate the effect of interface roughness on the performance of the sliding foundation. Test results indicate that the underneath soil softens significantly for a rough interface, resulting in soil ploughing and berm accumulation at the leading edge of the foundation. After 40 cycles, the accumulative settlement of the foundation with rough interface is approximately four times of that with smooth interface, which emphasises the remarkable effect of interface roughness condition on the performance of the tolerably mobile foundation during the whole-life operation.
Geodata Acquisition by Magnetic Resonance Measurements in Offshore Boreholes
Authors: Maas P , Burgers J , Peuchen J , Vrolijk M
Published: June 2024

Borehole geophysical logging allows acquisition of downhole magnetic resonance (DMR) measurements that can provide in situ data on unit weight and coefficient of permeability of soil and rock. DMR technology has an extensive track record for characterisation of deep (rock) formations and for ground engineering onshore. This paper presents DMR results obtained in sands, transitional soils, and clays at the investigation area for the IJmuiden Ver Wind Farm Sites I-IV, for water depths of about 20m to 45m, offshore Netherlands. The presented geodata acquisition is believed to represent a first-ever application for an offshore wind farm. In particular, the data provided added value on (1) transforming laboratory values on soil unit weight to in situ values and (2) in situ soil permeability for transitional soils.
Spudcan Penetration Assessment Using LDFEA and Comparison With Field Observations
Authors: Falepin H , Wallerand R
Published: June 2024

For jack-up sites in the North Sea where strong layers overlay weaker ones (classic punch through scenario), the use of large deformation finite element analysis can be of great support to achieve more accurate predictions of the spudcan penetration. As opposed to conventional methods based on closed form equations, this approach allows the soil to freely flow through the soil mesh and develop the prevailing failure mechanism(s) as the spudcan penetrates. This paper shares some recent experience where the use of Abaqus Coupled Eulerian-Lagrangian simulations combined with a Modified Mohr Coulomb soil model, modified to more accurately capture the dilative behaviour of very dense sand, reduced the uncertainty on the predicted leg penetration significantly and provided more insight into whether or not a punch through scenario was to be expected.
Effects of Partial Vibratory Driving on the Monopiles Lateral Stiffness - A Geomechanical Evaluation
Authors: Fischer J , Dührkop J , Bienen B
Published: June 2024

Recently, the demand for vibratory pile driving has increased significantly as it can be used to mitigate pile run risks. Typically, the piles are impact driven to target depth after vibrating to a predefined depth. The influence of vibratory driving on the lateral response of a monopile is described in several publications. This, however, covers piles that are vibrated to target depth. For partly vibrated piles no such results are available, yet the influence on the pile design must be taken into consideration. In the absence of published data, an approach based on the geomechanical behaviour of the soil at the interface to the pile is described in this paper. The focus lies on the friction fatigue phenomenon where stress changes are directly linked to the number of shear cycles. The outcome is discussed with regards to the lateral load-displacement behavior expected for partly vibrated monopiles.
An Automated Approach to Derive Pile p-y Curves From Bending Moment Data
Authors: Guevara M , Doherty J , Watson P
Published: June 2024

Due to the simplicity of its implementation, the p-y curve method has been extensively used by practitioners to model the soil-pile lateral behaviour of foundations with large length-to-diameter ratios. Although p-y curves are reported in the literature, there are cases when it is necessary to derive them based on experimental data. In these cases, a curve is fit to bending moment data at discretised depths, with soil pressure and deflection profiles determined by double differentiation and double integration respectively. The selection of an initial curve is more critical for deriving soil pressure than deflection, and a discussion is presented on the adequacy of different types of splines to fit physical modelling test data. The fitting process can be iterative and time consuming due to small variations that are inherent to the experimental process, therefore a constrained optimisation algorithm is proposed in this paper to fit splines to bending moment data using functions built-in to Matlab. While the authors argue that quintic smoothing splines provide a better fit to experimental data, the optimisation algorithm can be applied to any other curve fitting with small modifications.
Rippled Scour Depressions on Dogger Bank (North Sea): Mapping, Quantification and Geohazard Implications for Offshore Wind Farms
Authors: Riera R , Dimmock P S , Dix J K , Barwise A , Arlott L
Published: June 2024

Rippled Scour Depressions (RSD) are depressed bedforms containing characteristic ripples. They are a type of sorted bedform that mainly develop in areas with a shallow seafloor, strong waves/currents, and a thin mobile sand cover. This study focuses on RSD developed on Dogger Bank (North Sea) and presents: (1) qualitative descriptions; (2) semi-automated mapping of -12,500 RSD from two bathymetry datasets acquired 8 years apart; and (3) quantitative analysis of > 2,500 features. Most RSD are ephemeral, and they form fields whose location is controlled by seafloor geomorphology. These are abundant in shallow areas (< 24 m water depth) and in zones associated with abrupt topographic variations. Overall, RSD are large and shallow features, often having an area > 100 m2 and a maximum depth < 50 cm. However, RSD > 1 m deep are locally present, and their displacement might be a geohazard for renewable energy projects. This is a companion paper to Dix et al. (2023).
Impact of Soil-Conductor p-y Curves on Fatigue Life Assessment of Offshore Drilling Systems
Authors: Guevara M , Doherty J , Watson P , Gomes V , Mootz A , White D
Published: June 2024

During subsea drilling campaigns, the conductor is the outermost pipe of the well in contact with the soil near the seabed. It is used to prevent the walls of the borehole from collapsing and to provide axial support to the structure. While drilling, the wellhead system is connected to the drilling riser system, which links the seabed components to the drilling floating rig. Environmental loads acting on the entire system produce cycles of bending stress in the well that could lead to fatigue at critical locations, referred to as hot-spots. Estimating the fatigue life of hot-spots in the system is critical and the soil-conductor stiffness plays an important role. The forthcoming ISO 19901-4 recommendations (expected to be published shortly) provide two alternatives for deriving p-y curves for fatigue analysis of conductors: a 'spring-only' and a 'spring-dashpot' method. This paper provides a review of the p-y curves derived with the 'spring-only' method, for which care must be taken when interpreting results due to large variability in fatigue life predictions between different load cases. This conclusion is drawn by comparing the results of Finite Element (FE) modelling of a subsea system for two different loading scenarios and using three sets of p-y curves, including the ISO recommended method.
Suction Caisson Installation in Layered Soils – Observations From Installations
Authors: Hamdan N , Powell T , Grace D , MacBeath M , Jones L , Thumann V
Published: June 2024

Limited experience is available in the public domain for suction caisson installation in layered soil conditions. Complex and variable site conditions comprising silty sand, sand with silt/clay beds and layered soil conditions affect the installation and make predictions difficult. Various mechanisms can be encountered during suction caisson installation in layered soil conditions such as: reaching cavitation pressure limit, reaching structural capacity of caissons, lack of seal, piping, heave and tilt during self-weight penetration. This paper presents experience gained and key observations from the installation of 87 caissons in cohesionless soils and layered soil conditions at the Seagreen offshore wind farm (OWF) in the North Sea. Some of the successfully employed mitigation measures during installation are discussed and presented. Lessons learnt from the installations are also shared in this paper.
Site Characterisation Data Management, Computational Techniques and the Use of AGS Data
Authors: Patel A D , Shrimal D , Pickard N
Published: June 2024

As efforts increase in reaching net zero carbon emissions, the geotechnical engineering industry, particularly within the renewable energy sector, is being challenged to process vast amounts of geotechnical data with the aid of numerous database platforms. Management of site characterisation data is key at the onset of a project. The Association of Geotechnical and Geoenvironmental Specialists (AGS) committee have developed data formats which are used to capture site investigation data in an organised manner for electronic transfer. This has been proven to be invaluable; however, within the industry quality assessment of geotechnical data being received is of concern. It is the engineer's responsibility to ensure that not only the data provided is in the correct format, but the results are reviewed at an early stage to allow for the opportunity to gather additional information and inform further studies. This paper considers the advantages and disadvantages of using data management tools as well as the limitations with respect to the computational processing of geotechnical parameters within this platform.
Modelling Aspects of 2D Axisymmetric FEA for the Evaluation of Energy Losses of Tapered Monopiles
Authors: Zarzouras O , Cathie D , Perikleous G
Published: June 2024

During the driving of monopiles with a submerged tapered section, the current technical literature indicates that a significant amount of energy is lost into the surrounding water. This arises due pressure waves generated in the water by the monopile wall, and due to bending in the conical section. In order to more reliably predict those losses and to avoid overestimating them, a 2D axisymmetric numerical model was developed in Abaqus, considering numerical simulation of impact driving. This paper describes the development and testing of the numerical model of the pile-water-soil system, including alternative modelling scenarios and simulation aspects such as implicit and explicit formulations, mesh size and mesh dependency, the effect of material and contact damping, the water cavitation effect, etc. The numerical output used to evaluate the model, i.e. related to energy components and force, velocity and displacement signals, and the resulting energy losses are also discussed.
Quantifying the Vibro-Drivability of Monopiles in Sand: Prediction V. Experimental Results
Authors: El Haffar I , Ballard J C , Holeyman A , Hein Mazutti J , Bienen B , Randolph M F , Bransby M F
Published: June 2024

Significant uncertainty attached to the ability to predict with accuracy the installation behaviour of monopiles vibrodriven into the seabed is one of the aspects which has slowed down the take-up of vibroinstalled piles for offshore wind farms. Vibro-driven piles have the advantages of rapid installation and lower noise emissions during installation compared to standard impact driving, obviating the requirement for costly noise mitigation and use of very large impact hammers. This paper investigates the installation of monopiles by vibrodriving into sand 'seabeds'. This is done by presenting the results of novel experiments conducted in a geotechnical centrifuge and comparing these results (in terms of progression rates and refusal conditions) to independent predictions (conducted without knowing the results) using the Hypervib method. The Hypervib method is CPT-based and its empirical parameters have been validated and back-analysed from field cases. The comparisons reveal the conditions for which the Hypervib calculation method provides a good match and suggest areas where improvements in methodologies are required.
Characterization of Small-Strain Shear Modulus Through DAS
Authors: Callens C , Stuyts B , Lanckriet T , Williams E
Published: June 2024

The offshore subsurface is a highly dynamic place where seismic waves are constantly generated due to the presence of offshore infrastructure, earthquakes, landslides etc. In recent years, Distributed acoustic sensing or DAS has drawn the attention of geologists and geophysicists for its capability of monitoring seismic activity. Distributed acoustic sensors embedded in power cables on the seabed are able to record seismic waves from which Scholte surface waves are separated by scientists. By means of inversion processes, a shear-wave velocity profile can be derived characterizing the soil. However, these techniques are futile if they're not able to represent reality. Therefore, a comparative study is presented quantifying the performance of DAS-derived velocity profiles against conventional CPT correlation-based profiles in North Sea soils. In a first attempt, the model by Chapman - Godin (2001) is used to perform the inversion leading to a bias towards clayey soils. The model is improved using the study by Haney - Tsai (2017) resulting in an unbiased model.
Comparative Evaluation of Approaches for Modelling Footing Penetration in Layered Soils During Jack-Up Installation
Authors: Zheng T , Whyte S , Rattley M , Alexander J
Published: June 2024

Prior to any jack-up installation, a Leg Penetration Assessment is generally conducted in order to predict the footing penetration behaviour during installation. The most common methods of analysis follow simplified Rule-Based (RB) approaches (as described in ISO 19905-1 Part 1, SNAME Technical - Research Bulletin 5-5A), which involve the use of simple relationships to calculate bearing capacity at a range of embedment depths, allowing for continuous load-penetration curves to be interpolated. These methods are most suited to reasonably simple, homogenous soil profiles, as they typically involve relatively crude assumptions for analysing complex, highly layered soils. For such cases, more advanced numerical analysis methods may be utilised to model the behaviour more rigorously. Standard Finite Element Analysis (FEA) and Large Deformation Finite Element Analysis (LDFEA) are two such approaches which allow for higher fidelity modelling, although are more time-consuming and complex. In this study, RB, FEA, and LDFEA approaches have been used to predict the penetration behaviour at two locations with complex, layered soil profiles. This paper aims to compare the results of the three approaches, considering the relative merits and limitations of each method and offering suggestions for key refinements which could be adopted to improve accuracy.
Analysing Monopile Response With a Critical State Model for Sands
Authors: Castillo-Fuentes E , Zdravkovic L , Potts D M
Published: June 2024

Advanced constitutive models, such as those formulated in the bounding surface plasticity framework, enable a reliable representation of sand behaviour and have been shown successful in predicting the response of monopiles subjected to monotonic lateral loading. They, however, have a large number of input parameters which may require a lengthy calibration process. The current paper explores the application of a simpler NorSand constitutive model in the modelling of monopile response under monotonic lateral loading. This model, formulated in the critical state framework, requires a small number of parameters for its calibration. The NorSand formulation is briefly introduced and the model is calibrated against experimental data for Dunkirk sand. Simulations of recent lateral pile load tests in this dense marine sand are then presented and the results compared against field measurements, demonstrating that predictions are in good agreement with the field measurements.
Artificial Intelligence (AI) Driven 3D Point Scanner for Monitoring Soil Plug Hazards During the Installation of Suction Caisson Foundations
Authors: Williams B , Suryasentana S , Perry M , Donaldson K
Published: June 2024

Soil plug hazards pose a significant risk to the successful installation of suction caisson foundations but are currently inadequately monitored using only a single beam echosounder. To address this issue, a new artificial intelligence (AI) driven three-dimensional (3D) point scanner is proposed for monitoring soil plug hazards. The proposed scanner is controlled using a Bayesian optimisation (BO) algorithm, which automatically adapts its data acquisition path in real-time based on previously acquired measurements. Preliminary laboratory tests were conducted to assess the effectiveness of the proposed scanner. The results showed that the proposed scanner can accurately estimate 3D surfaces with fewer measurement points than a comparable scanner using the conventional scanning method, typically used in existing 3D point scanners. As the proposed scanner can estimate the state of the entire surface in much shorter time than existing sensors, it potentially offers a more effective method to monitor soil plug hazards.
Vibro-Driveability of Monopiles Using Hypervib and GRLWEAP Approaches
Authors: El Haffar I , Ballard J C , Maron M , Holeyman A , Perikleous G
Published: June 2024

The use of vibro-driving for the installation of large diameter monopiles is investigated in soil conditions consisting primarily of very dense sand and sand/silt mixtures. A feasibility study of vibrodriveability installation has been performed on a monopile geometry that has been assumed to support future wind turbines projects. The 'Hypervib' methodology complemented with GRLWEAP simulations was applied to assess the feasibility of the monopile installation. Best estimate (BE) and high estimate (HE) soil conditions were considered and combined with driving frequencies of 23.3 Hz and 20 Hz, leading to a total of four studied cases for a given vibratory hammer. Hypervib and GRLWEAP models are shown to produce highly contrasted predictions of penetration rates. Hypervib model predicts that the four studied cases can be installed to the target depth in a time duration going from 0.5 to 3 hours. On the contrary, GRLWEAP predicts that only two out of the four cases can be installed to the target depth. GRLWEAP predicts very short driving time for the cases it considers as feasible. GRLWEAP is also used to estimate vibratory force amplification to enhance the Hypervib prediction.
IJmuiden Ver Windfarm Zone: Increasing the Resolution of the Southern North Sea Stratigraphy Using Iterative Ground Modelling Techniques
Authors: Eady H , Bloore C , Gerritsma D
Published: June 2024

Iterative ground modelling techniques can reveal a more accurate representation of ground conditions at a site or study area through careful selection of data acquisition parameters and data enhancement. At the IJmuiden Ver Wind Farm Zones, a complex stratigraphic framework has been revealed which was not previously understood by using a ground model-led approach to site characterisation. This paper highlights the change in interpretative quality following dedicated investigation planning and data reprocessing allowing highly detailed soil province maps and stratigraphic frameworks to be established.
Clay Strength Re-Gain Following Cycling & Consolidation - Application to Suction Caisson Foundations Part II
Authors: Hamdan N , Lehane B M , Powell T , Joseph T , Jones L
Published: June 2024

Suction caissons have recently become a popular foundation type for offshore renewable structures. They are usually installed by creating differential internal pressure to embed the foundation to its target penetration. The required installation pressure depends on the soil resistance, submerged weight of caisson and its geometry. Installation pressure can be reduced when adopting two-way pressure cycling. This process involves cycling the pump flow rate to cause small upward and downward movements of the caisson which soften the clay strength along the shaft hence reducing the required pressure for installation. This paper presents results from a suite of cyclic simple shear (CSS) tests which was conducted to gain understanding of the effects of cycling on the strength of clay samples and the subsequent strength re-gain with time. Soil samples were subjected to 10 two-way cycles, consolidated for various periods of time and monotonically sheared. Soil strengths post-cycling and consolidation were measured. Results indicated that the soil strength is fully recovered at laboratory scale. Recommendations on the effect of the applied two-way cycling on clay samples and subsequent strength post-cycling re-gain are drawn. The paper concludes on practical application of results and implication on cyclically installed suction caissons for the Offshore Renewable Sector.
A Method for Predicting the Drilling Rate of Penetration for Pile Foundations Installed Into Rock
Authors: Jones L , Mclean R , Costa L
Published: June 2024

Installing pile foundations within rock strata at offshore sites poses a variety of challenges. For sites where it is necessary to drill into rock to install piles, a key concern is the duration required to drill the holes in which the piles will be placed, since this can have significant technical and commercial implications. Utilising recent experience from an offshore wind development, this paper outlines a method for predicting the drilling rate of penetration (ROP) for a range of rock types and rock strengths. The proposed method is based on the well-established Mechanical Specific Energy concept and is shown to provide reasonable agreement with site observations.
Load-Time Failure Envelopes for Suction Caissons Under Sustained Vertical Loading
Authors: Rosati A , Desideri A , Rampello S , Randolph M F , Gaudin C
Published: June 2024

Suction caissons are established as a reliable anchoring system to moor a range of offshore floating facilities. Under sustained loads, generally characterized by long durations, the caisson holding capacity against uplift loading, that relies on suction pressures induced within and at the base of the soil plug, is expected to reduce over time, due to the equalization of pore water pressures. The scarcity of studies addressing this sustained loading problem has motivated this study, in which the response of suction caissons in soft clay subjected to sustained vertical uplift loads is investigated through finite element simulations and centrifuge model tests. Results are presented in the form of failure envelopes in the load-time plane, correlating, for each failure mechanism detected, the load level to the corresponding holding time. The findings of this study are considered useful for concept design purposes, when sustained loads govern the caisson design.
Innovative Technologies for Offshore Oil and Gas Industry: a Brief Review of Survey, Monitoring and Inspection Methods for Energy Transition
Authors: Hariharan G N
Published: June 2024

External acoustic inspection including Cathodic Protection (CP) survey of submarine Oil - Gas (O&G) trunk/ feeder, collector and in-field lines completing design life are carried out at an interval of five years in the offshore of India. Critical segments of pipelines that deviate from engineering design are reported as anomalous, and necessary recommendations for maintenance are provided, to extend its life. Fugro India Marine has been carrying out inspection survey of subsea pipelines for several decades. Offshore wind assets, as they age, need inspection and maintenance, to increase their lifetime. Inspection, maintenance and repair (IMR) are key components of integrity management system, which aim to reduce the risk of failure and extend the life of subsea installations. Innovative technologies in the offshore O&G industry and recent advances in it may be adapted in the offshore wind farm industry, which has been briefly reviewed in this paper.
Medusa DMT for Geotechnical and Geophysical Offshore Testing
Authors: Marchetti D , Sacchetto M
Published: June 2024

The Medusa DMT is a recently developed fully automated version of the Marchetti Flat Plate Dilatometer (DMT), which was first introduced in the late 70s and is commonly employed today in onshore and nearshore site investigation projects. The new enhanced device is a self-contained hydraulic probe able to autonomously perform standard DMT tests, without requiring a gas tank, a pneumatic cable, a control unit and a skilled operator for inflating and deflating the dilatometer membrane. The tool may operate as cableless or employing an electric cable for consulting real time results during test execution. The traditional pneumatic equipment was limited to only onshore and nearshore projects, up to about 30 m water depth. The Medusa DMT may be deployed also in deep offshore surveys, currently down to 1500 m. Within a project for the design of the new breakwater dam of Genova, in northwest Italy, CPT and DMT were selected for the geotechnical characterization of the upper soil deposits in terms of stratigraphy, compressibility, strength, permeability and possibly providing estimations of stress state and stress history parameters. The water depth ranged between 16 m and 49 m, while the deepest test was a DMT down to 26.4 m below the seabed. The paper describes the equipment, setup and test procedure adopted for this project, employing a seabed penetrometer (Manta), CPTU and Medusa DMT testing equipment.
Evaluation of p-y Model for Laterally Loaded Piles in Normally Consolidated Soil
Authors: Komolafe O , Aubeny C P
Published: June 2024

This paper presents comparisons from a Class A prediction event comparing model predictions with measured pile/conductor response to applied lateral loads. This event was organized by the National Geotechnical Centrifuge Facility (NGCF) at the University of Western Australia (UWA) and performed as part of the 2020 International Symposium on Frontiers in Offshore Geotechnics (ISFOG 2020) to assess uncertainties in predicting monotonic and cyclic lateral response of conductors. The authors utilized an empirical model published in 2020 to generate the submitted predictions. The empirical model utilizes equivalent cyclic soil spring (p-y) approach in describing lateral soil resistance on offshore well conductors and piles in normally to lightly overconsolidated clays. The current form of the empirical model requires the soil's undrained shear strength profile, the geometry and basic material properties of the conductor as input parameters. With relatively few input parameters, the comparison of the predicted response to the actual measurements ranged from good to excellent, with the predictions at 0.1D pile head cyclic displacement being the most impressive. The deviations for other load scenarios varied and is discussed in the paper. Further calibrations have been made to this new database to improve the performance of the model.
Prediction of Submarine Turbidity Currents Using Stacked LSTMs with Tree-Structured Parzen Estimator Optimisation
Authors: Fazel Mojtahedi F , Yousefpour N , Chow S H , Cassidy M
Published: June 2024

Turbidity currents are density flow of sediments that occur intermittently in deep seas. Large and fast turbidity currents can cut and erode continental margins and damage vital infrastructures such as seabed telecommunications cables. This paper aims to evaluate the application of Deep Learning method in the forecast of submarine turbidity currents, using long short-term memory networks (LSTM). The proposed LSTM models were trained on turbidity current datasets gathered by Ocean Network Canada, incorporating oceano-graphic, hydrographic, and sedimentological data. The proposed forecasting model for turbidity currents demonstrated high accuracy and reliability by utilising a Bayesian optimisation algorithm for hyperparameter tuning, along with Monte Carlo dropout and deep ensemble techniques for uncertainty assessment. Velocity predictions exhibited a 6.5% and 9% error, while turbidity forecasts exhibited a 5% and 8% error, based on evaluation criteria of mean absolute percentage error and normalised root mean square error. These findings suggest that the proposed deep learning model could serve as a valuable tool for monitoring and predicting turbidity currents.
El habitar en movimiento: el caso de los trabajadores móviles digitales en Lima (Perú)
Authors: Ponce-Romero César
Published: June 2024

En la última década, se ha generado un incremento exponencial de los servicios de repartidores de alimentos por aplicativos en las ciudades de América Latina, suponiendo desafíos para los estudios urbanos. El presente artículo contribuye a las investigaciones enfocadas en las condiciones laborales de los repartidores desde un enfoque que aborda las nuevas formas de habitar urbano producidas por estos actores. A partir de un estudio de caso en la ciudad de Lima (Perú) y desde un enfoque etnográfico, se identifica el rol conector de los repartidores en una zona de alta concentración de actividades financieras. Se argumenta que las formas de habitar se producen en contextos de vulnerabilidad, enfatizando en el control del municipio hacia el uso del espacio público. Se concluye resaltando la importancia de las experiencias de habitar como dimensión de análisis sobre las prácticas laborales de los trabajadores móviles digitales.
Exploración sobre movilidades del cuidado: un análisis preliminar en Ciudad de México
Authors: Soto-Villagrán Paula
Published: June 2024

El persistente vínculo entre género y movilidad ha ido creciendo como tema de indagación tanto en los trabajos académicos como en las agendas políticas de transporte y movilidad en América Latina. En efecto, el reconocimiento de los sesgos de género en la planificación del transporte y sus efectos en la medición de los patrones de movilidad cotidiana de las mujeres ha ampliado las posibilidades de investigación sobre el papel de género en el estudio de los viajes que realizan cotidianamente las mujeres en los espacios urbanos. Sin embargo, las indagaciones sobre el vínculo entre género, trabajo de cuidados y movilidad son aún limitadas. Basándonos en un estudio mixto que integra una encuesta de movilidad y cuidados aplicada en Ciudad de México junto a una estrategia cualitativa móvil de investigación, este artículo explora los viajes de cuidado de mujeres y sus potenciales implicancias en el diseño de los espacios públicos de movilidad.
Calles peatonales: investigando el impacto sobre la actividad en el espacio público y las plantas bajas de la edificación en Torrelodones, España
Authors: Ruiz-Apilánez Borja , Fernández-Muñoz Santiago , Solís-Trapero Eloy
Published: June 2024

Las peatonalizaciones suelen suponer la transformación física de la urbanización de las calles afectadas. Este artículo investiga sus efectos sobre la actividad humana, en el caso del pequeño municipio madrileño de Torrelodones (España). Para ello, estudia y compara los flujos peatonales, las actividades estacionarias desarrolladas en el espacio público, y la actividad de las plantas bajas de la edificación adyacente, en tres momentos diferentes. Primero, en 2013, antes de la reurbanización realizada en 2014-2015, pero con el acceso ya restringido al tráfico rodado. A los dos años, en 2017, y cinco años después, en 2022, para investigar la situación a corto y medio plazo. El estudio muestra un aumento significativo en la actividad estacionaria, sobre todo en la vinculada a la hostelería, que se mantiene en los años siguientes, transformando los usos de locales adyacentes.
Iridescent Patterns Production from Solid Film Cellulose Nanocrystals Prepared from Coffee Husks
Authors: Nyaruai Catherine , Ollengo Dr Moses , Muthakia Gerald
Published: June 2024

The dire need for environmental conservation has spurred the exploration of novel approaches for developing biodegradable and sustainable materials sourced from natural origins, particularly for engineering applications and these include cellulose. Utilizing coffee husks, a waste product from coffee production, offers a sustainable source of cellulose, effectively diverting waste from the environment and turning it into a valuable and profitable resource. The cellulose content within coffee husks were extracted through alkaline treatment, after which, acid hydrolysis was done, yielding cellulose nanocrystals (CNCs) that were utilised to create iridescent films. The process involved treating the coffee husks with sodium hydroxide to obtain cellulose, followed by bleaching with sodium hypochlorite. Acid hydrolysis using gaseous HCl was then employed yielding cellulose nanocrystals. The application of HCl improved the iridescent film quality for secure sheets by preventing the whiskers that are usually seen when sulfuric acid is used. This raises the overall quality and security of the finished product. To avoid contamination, the CNC suspension was carefully transferred into Petri dishes made of polystyrene, and the suspension evaporated at controlled temperature in an oven, resulting in a solid CNC film. To introduce patterns on the film, the Petri dish containing the CNC suspension was placed on a mold engraved with a specific pattern. Heating of the mold imparted different colors onto the film. The outcome of heating the CNC Suspension involved the self-assembly of CNCs into a multitude of colorful and iridescent films possessing unique optical properties. Additionally, these films exhibited water resistance, luminous color variations based on viewing angles, fluorescence, and reflection of left-handed circularly. The value addition of coffee husk waste, which makes it a cleaner environmental product while producing security sheets, is the significance of this work particularly the inclusion of cyclic redundancy, which guarantees improved security features.