Foundation Design Research Articles

Ring penetrometer for interface shear testing on sand under low-stress conditions

Accurate characterisation of near-surface soils is essential for the design of subsea cables, pipelines, and shallow foundations. Conventional laboratory testing equipment is not well adapted to these applications where the operative stress levels are typically <10 kPa. This paper presents and interprets a comprehensive test campaign using a novel flat ring penetrometer. This device measures interface friction at stress levels as low as 1 kPa. Drained friction parameters for a range of sands obtained from the ring penetrometer are compared to other friction measurements from centrifuge sled and interface shear box tests. The results demonstrate the repeatability of the ring penetrometer, and the benefit of the simple but rigorous interpretation approach. The residual friction measured in the ring and centrifuge sled tests shows no dependency on stress level, which contrasts with the interface shear box results. It is shown that the apparent stress-dependency could be an artefact of system friction in the shear box. A correlation between friction coefficient and device settlement rate is identified, with the maximum friction mobilised as the settlement rate approaches zero, consistent with the combined bearing-sliding failure mechanism. These findings highlight the value of the ring device for interface friction measurement.

Improving the properties of clay soils in foundations through compaction and the integration of fibres and cement

Clay soils present significant challenges in engineering applications, particularly in the design and construction of foundations, due to their susceptibility to swelling and shrinkage. This research investigates the enhancement of clay soils through the incorporation of fibres, compaction, and cement, based on a comprehensive series of tests conducted at the Public Works Laboratory in Adrar, southern Algeria. The tests adhered strictly to technical standards in soil mechanics, examining the physical, mechanical, and thermal properties of the clay soil. The results demonstrated that applying a compressive strength of 2.5 MPa and incorporating palm and glass fibres in proportions ranging from 0% to 0.3% reduced bulk density by 0.95% to 7%. The capillary water absorption rate increased by 10.61% to 12.63%, while compressive strength improved by 11.4% to 34.37%. Furthermore, thermal conductivity decreased by 0.71% to 11.9%. These findings provide valuable insights into the properties of clay soils and the observed improvements. It can be concluded that soil enhancement through various materials and fibres is viable and yields positive outcomes in geotechnical applications.

Ultimate load bearing of helical piles prediction and evaluation using machine learning-based algorithms

ABSTRACT This study aims to predict the Ultimate Load-Bearing (ULB) capacity of Helical Piles (HP) using six Machine Learning Algorithms (MLA) on an in situ-based 110 pile load tests including a wide range of pile properties: shaft diameters (73–406 mm), helix diameters (254–762 mm), helix spacing (300–1000 mm), number of helices (1–6), pile lengths (2.4–16 m), and helix thicknesses (6–12 mm). The measured axial ULB is analysed using the Brinch-Hansen 80% criterion and 5% criterion of the average diameter of the helices. Load-displacement curves were fitted using the Hyperbolic Function. MLA including Multi Linear Regression (MLR), K-Nearest Neighbors (KNN), Decision Tree (DT), Random Forest, eXtreme Gradient Boosting, and Support Vector Regression were optimised to grid search for hyperparameters like neighbour count, tree depth, learning rate, and kernel type. Input parameters were categorised into Geometric and Soil Properties packages. Results indicate that the DT algorithm excelled in pullout loading, KNN in compression loading, and MLR for Brinch-Hansen 80% criterion estimations. The input parameters related to the soil surrounding the pile helices have the most impact on the ULB prediction of HP. This study enhances HP foundation design by enabling data-driven decisions for optimal pile selection and configuration.

Combined rupture mechanisms of shallow foundations: implications in limit state design

The design of shallow foundations at the ultimate limit state is conventionally performed assuming a foundation structure that does not undergo any yielding, although current technical standards require the investigation of any possible rupture mechanism, including combined rupture in the soil and in the foundation structure. The aim of this work is to study the practical implications of including the analysis of combined rupture mechanisms (involving both soil and foundation structure) in shallow foundation design under drained and undrained conditions within the framework of current technical standards. Two case studies are presented and tackled with a recent novel strategy for numerical simulations. It is shown that conventional foundation design methods may not be reliable when evaluating internal actions within a spread foundation, hence foundation yielding may not be correctly detected, implying that the bearing capacity of a foundation can be severely overestimated in conventional practice, in particular under drained conditions. On the other hand, foundation yielding can be exploited to reduce the amount of needed reinforcement, while still satisfying both geotechnical and structural technical standards.

Estimation of dynamic soil properties for geotechnical analysis in the Niger Delta using index testing and empirical correlations

This study investigated geotechnical properties of subsurface soils from Mbiama town in Rivers State, Niger Delta region through laboratory index testing and development of empirical correlations to estimate dynamic soil parameters. Grain size analyses revealed heterogeneous stratigraphy transitioning from upper clayey sands to lower gravelly sands deposited under changing fluvio-deltaic conditions. Atterberg limits exhibited decreasing plasticity trends with depth confirming the textural variations. Laboratory data conforms to layering architecture inferred from depositional facies analyses. Predictive models were developed relating Standard Penetration Test blow counts (SPT-N) and shear wave velocity (Vs) to depth, moisture content and percentage sand. High regression coefficients validated models' accuracy in reproducing over 90% of field measurements. Factor of safety against liquefaction was correlated to SPT-N, accounting for density-dependent properties. Index-based characterizations aligned well with trends predicted by the empirical correlations. This research demonstrated robust indirect estimation of dynamic geotechnical indices for foundation design and seismic risk analysis in data-scarce Niger Delta through standardized field and laboratory index testing integrated with depositionally-linked predictive models.

Increasing the Performance of Ring Foundation to Lateral Loads by using a Skirt Foundation

In numerous engineering foundation designs, the influence of lateral loads is frequently underestimated in calculations. Consequently, recent studies have increasingly concentrated on comprehending the behavior of soil and foundations when subjected to lateral load influences. The present study aims to examine the performance of ring foundations, a common engineering solution employed in the construction of tall and slender structures that are vulnerable to lateral loads, such as those exerted by wind forces. The objective of this study is to enhance the lateral resistance of ring foundations by incorporating skirt foundations. The efficacy of skirt foundations was evaluated through a series of tests conducted on sandy soils of varying densities, ranging from dense to medium loose sand. Subsequently, lateral loads were applied to the ring foundations, both with and without skirt foundations. The results demonstrated that the lateral resistance increased in proportion to the ratio between the inner and outer diameters. Furthermore, the improvement rate was enhanced by the addition of the skirt foundation. Additionally, the lateral resistance increased with increasing the skirt foundation depth, reaching a maximum of approximately 50-100%. Similarly, an increase in the skirt inclination ratio to 450 resulted in a lateral resistance increase of up to 650%.

Numerical Study of Local Scour and Hydrodynamic Pressure of Complex Bridge Piers

This study uses Computational Fluid Dynamics to investigate bridge foundations' scouring process and hydrodynamic pressure caused by an extreme flood. A Large Eddy Simulation model, compiled with a Navier-Stokes equations model, is used to compute the fluid motion with the Volume-of-Fluid to track the motion of the water surface. A Discontinuous Bi-viscosity rheological model describes the river's muddy bottom properties. The numerical results are further analyzed to understand the influence of exposed, closely spaced piles bridge on the scouring process. The results show that the extended foundation (with ten piles) has a maximum scour depth of approximately 10 m, which is 2.0 m greater than the non-extended foundation (with six piles). Specifically, the high velocity surrounding the exposed, tightly spaced piles may exacerbate the scouring problem. The design code suggests a hydrodynamic pressure of 10.9 kPa and 10.1 kPa for six and ten piles, respectively. The front-row piles' hydrodynamic loading is underestimated in the bridge design code. The maximum hydrodynamic pressure occurs at the front piles at roughly 1.8PI, where PI represents the hydrodynamic pressure. The velocity and hydrodynamic pressure at each pile are calculated, comparable with that in the bridge design code. This finding is important for the design of bridge foundations with exposed piles.

Analysis of soil bearing capacity to determine foundation design in Ngawi City, Indonesia

Abstract Improving economic value in a region can be achieved through planned infrastructure support. As one of the biggest shopping centers, Ngawi Big Market has revitalization activity. Before beginning the revitalization process, it is crucial to test the ability of soil to withstand the load, which is called the soil bearing capacity. In the process of this research, the analysis was carried out by evaluating geological and geotechnical conditions, and calculations of soil bearing capacity values. Analysis of soil bearing capacity value was using NSPT data which uses the equation from Luciano Decourt along data from laboratory tests. The lithology of the research area consists of siltstone, and the drilling results consist of silt, fine sand and clay. The land area of Ngawi Big Market is 15,000m2 with the building area of the previous market being 14,500m2. The permitted lowest bearing capacity is at point BH-T3, namely 6.7 tons at a depth of 2.0 meters, while the highest is at point BH-T1, namely 380.3 tons at a depth of 20.00 meters. Based on the results of the analysis, Ngawi Big Market’s revitalization project recommended to carry out the geotechnical engineering to strengthen the soil as well as detailed calculations of building loads so that they do not exceed the permitted bearing capacity.

Design and Structural Analysis of a G+20 Multi-Storey Commercial Complex Using STAAD.Pro

This project encompasses the layout, design, analysis, planning, and estimation of a G+20 commercial building located in Hyderabad, developed on a plot measuring 21.33 m × 10.67 m. The layout and drafting were executed using AutoCAD, providing precise structural drawings that also served as input for structural analysis and design in STAAD Pro. The analysis identified critical forces acting on various structural members and generated reinforcement schedules. Concrete take-offs and reinforcement weights were determined using STAAD Pro, streamlining cost estimation and material planning. The foundation was designed as an isolated footing based on soil conditions, with design values computed in STAAD Foundation. This approach integrated drafting, design, and analysis, ensuring accurate and efficient structural planning. Keywords: G+20 commercial building, AutoCAD, STAAD Pro, structural analysis, foundation design, cost estimation, isolated footing, Hyderabad.

Prediction of undrained shear strength based on KMR model

The accurate prediction of undrained shear strength is of significant importance in areas such as slope stability, earthquake resistance, and pile foundation design. Therefore, enhancing the accuracy of undrained shear strength prediction is crucial. The research results indicate that employing the KMR model can improve the computational accuracy by 4.4% to 18.9%. Furthermore, compared to conventional empirical formulas, the KMR model evidently processes data more rapidly and can predict relevant parameters more accurately. This method provides a new research idea to some extent for addressing the issue of low prediction accuracy of traditional machine learning models for geotechnical parameters.

Numerical investigation on rotation accumulation and natural frequency degradation for offshore wind turbine in clays

Prolonged lateral cyclic loading leads to soil stiffness degradation around offshore wind turbine (OWT) foundations, which reduces the system's natural frequency and increases the accumulation of foundation rotation angle. Proper evaluation of natural frequency and rotation angle is crucial for the design of OWT foundations. This study develops a two-stages numerical approach to calculate the fundamental frequency of OWT systems considering the foundation stiffness degradation by integrating a stiffness degradation model of soft clays with a simplified three-spring model. Subsequently, it investigates the evolution of accumulated rotation and natural frequency for three foundation types—monopile, monopod bucket, and hybrid monopile-bucket—throughout their service life. It is observed that the hybrid foundation shows the smallest rotation in the first cycle, attributable to its relatively high initial stiffness compared to the other two foundations with the same steel consumption. However, it also exhibits the highest rate of cumulative rotation growth. At the same load level, the monopod bucket foundation exhibits the largest cumulative rotation angle due to its lower bearing capacity, and the degradation of natural frequency is most pronounced for monopod bucket OWT. For all three foundation configurations, increasing either the pile diameter or the bucket diameter is the most effective approach to reduce the cumulative rotation angle and improve natural frequency degradation, while maintaining the same steel consumption. These findings should be considered in the design of OWT foundations.

Analysis of the Space Frame Structure of the Cileungsi Fly Over Tower Bogor Regency

This research is part of the plan of the Bogor Regency government, especially Cileungsi District, in arranging the Cileungsi flyover which is currently filled with garbage and used as a shadow terminal, making the area look slum. The arrangement effort is made to create a comfortable, neat flyover that can become an icon of Bogor Regency. The research aims to produce a portal tower flyover design that is aesthetic, unique, sturdy, and meets the strength and stability standards of the structure according to local conditions. The analysis was carried out using SAP2000 software to model the three-dimensional space structure and identify the strength, stability, and deflection of the structure. The LRFD (Load Resistance Factor Design) method is used in calculating the bearing capacity of the structure. The results of the analysis show that the space frame structure made of steel pipes has stable and rigid behavior, meeting all work loads, including dead loads, live loads, wind, and earthquakes. The design of the 13-meter deep pile foundation has also been proven to be able to withstand loads safely. The design of the space frame structure made of steel pipes for the Cileungsi flyover portal tower is declared strong, stable, and safe to implement. This structure can be used as a new icon for Bogor Regency, especially Cileungsi District. The implementation of this design requires detailed depiction as a construction guideline in the field.

Influence of Foundation–Soil–Foundation Interaction on the Dynamic Response of Offshore Wind Turbine Jackets Founded on Buckets

This study investigates the impact of soil–structure interaction (SSI) and foundation–soil–foundation interaction (FSFI) on the dynamic behaviour of jacket substructures founded on buckets for offshore wind turbines. A parametric analysis was conducted, focusing on critical load cases for conservative foundation design. Different load configurations were examined: collinear wind and wave (fluid–structure interaction) loads, along with misaligned configurations at 45° and 90°, to assess the impact of different loading directions. The dynamic response was evaluated through key structural parameters, including axial forces, shear forces, bending moments, and stresses on the jacket. Simulations employed the National Renewable Energy Laboratory (NREL) 5MW offshore wind turbine mounted on the OC4 project jacket founded on suction buckets. An additional optimised jacket design was also studied for comparison. An OpenFAST model incorporating SSI and FSFI considering a homogeneous soil profile was employed for the dynamic analysis. The results highlight the significant role of the FSFI on the dynamic behaviour of multi-supported jacket substructure, affecting the natural frequency, acceleration responses, and internal forces.

Estimating soil strength using ultra high resolution seismic: A case study from a shallow water windfarm

The increasing global reliance on offshore wind farms as a sustainable energy source necessitates precise soil assessment for foundation design, due to their high foundation costs and complex integration into marine environments. This study explores the utilization of ultra-high-resolution seismic data in conjunction with cone penetration test data for soil strength estimation in offshore wind farm development. We propose a convolutional neural network-based approach that leverages ultra-high-resolution seismic data for direct soil strength estimation, aiming to address the challenges of limited cone penetration test measurements and potential overfitting in complex geological settings. Our methodology involves preprocessing ultra-high-resolution seismic and cone penetration test data, interpreting and integrating geological unit information, and applying repeated k-fold cross-validation to evaluate model performance. The field data results demonstrate the model's efficacy in accurately predicting cone penetration test curve trends, albeit with some amplitude discrepancies. We highlight the significance of geological interpretation in predicting soil strength and identify the dependency on valid data within each geological unit as a limitation.

Study of the Correlation between Pressuremeter Limit Pressure and Dynamic Resistance obtained by the Dynamic Probing Super Heavy (DPSH) of the Sands of Lome in Togo

The design of building foundations relies on a good understanding of the bearing capacity of soils, which is determined by various in situ testing methods, such as pressuremeter and penetrometer tests. The pressuremeter test provides valuable information on the strength and deformability of soils at depth, while the dynamic cone penetrometer more easily assesses the dynamic resistance of the soil under dynamic loads. In this study, correlations were established between the dynamic resistance qd measured with the dynamic probing super heavy and the limit pressure pL obtained with the Menard pressuremeter. The data collected come from geotechnical investigations carried out on sandy soils of Lome in Togo. For these soils, the ratio is in the following interval: 8.27 ≤ qd/pL ≤ 9.74. Keywords: correlation, dynamic resistance, limit pressure, sand.

Evolutionary design features of virtual fashion brand collections: a three-year analysis in the Metaverse era

ABSTRACT This study aimed to investigate the evolutionary design features in recent virtual fashion brand collections, analysing 314 design images from leading brands, such as Auroboros, Tribute, Republiqe, The Fabricant, and RTFKT. The analysis classified key design elements–colour, silhouette, texture, and textile patterns – into three phases: embryonic, transitional, and expansion. Findings revealed that the embryonic phase prioritises symbolising brand identities and goals as main design elements. The transitional phase marked a shift toward increased collaboration and experimental designs in response to emerging trends. In the expansion phase, collections shifted away from foundational design elements, displaying mature aesthetics and greater collaboration. These findings identify the evolutionary design features of virtual fashion in the Metaverse era and highlight insights into its consistency with contemporary fashion sensibilities. This research contributes to establishing a crucial knowledge base for research into the development of affective design systems, addressing consumer emotional requirements in virtual fashion design.

Evaluation, sampling and testing methods for offshore disturbed sands with plastic fines: A case study

Sandy seabed, prevalent near continental shelves, often contains fines that obviously affect their apparent behaviour. The variation in the physical properties of sands and fines, the difference between seismic and marine wave loads, and the challenges in obtaining accurate geotechnical parameters and undisturbed samples for analysis make it difficult to effectively evaluate the properties of sands with plastic fines in offshore engineering. To address this issue, a method for discriminating and re-sampling sands with plastic fines is suggested, along with a case study to assess the static and dynamic behaviours of such sands from an offshore site in the South China Sea. In this study, evaluation processes for detecting the presence of fines in sands and classifying them as plastic or non-plastic are first recommended to gain a better understanding of such sands. Then, a reconstitution approach of re-sampling for disturbed sand samples from site and compactness assessment guided by the optimum moisture content, is suggested to restore their in-situ characteristics, addressing the difficulty in obtaining undisturbed sand samples. Subsequently, the failure behavior and shear strain development under cyclic loading are analyzed via a cyclic contour diagram to evaluate their mechanical properties under marine environmental loads. The obtained contour diagrams can be further integrated into the constitutive model in subsequent research and used in finite element analysis to simplify the computation for marine foundation design. These results can provide valuable insights for improving understandings and engineering practices related to sandy seabed with plastic fines in offshore environments.

Enhancing teaching materials development course with the ICARE learning model in e-learning

Using e-learning in higher education has many important benefits and advantages in todays world of education. Therefore, this research aims to develop e-learning based on the introduction, connection, application, reflection, extend (ICARE) learning model for developing teaching materials courses in the Faculty of Education, Universitas Pendidikan Ganesha. The Hannafin and Peck development model was adopted as a foundational method, and the digital content developed was subjected to formative evaluation methods, including i) expert validation, ii) individual assessment, and iii) small group evaluation. To ascertain the quality of the developed content, the research engaged 3 expert evaluators, each specializing in media, instructional design, and content. Concurrently, individual evaluation was carried out with 3 students, followed by a small group evaluation involving 9 additional students. Data collection techniques involved both observational measures and questionnaire-based inquiries. The expert assessment showed that the design, media, and content dimensions all fell within the "very good" category. Student reactions, as measured through both individual and small group evaluations, consistently aligned with the "very good" category. Therefore, the attractiveness and practicality of electronic learning (e-learning) fell under the "very good" classification, due to the implementation of the ICARE learning model as the foundational design principle.

Approaches and Challenges in FEED and Detailed Design Process of Floating Substructures

Abstract In the FEED or detailed design phases, the floating foundation designers have to deal with complex structural design aspects and meet certification or class requirements for structural verifications, such as yield and buckling checks as well as fatigue checks for steel structures. The designer faces several challenges during the structural verification process, starting with the accurate definition of the complex external load state with the simultaneous action of aerodynamic, hydrostatic and hydrodynamic loads, inertia and mooring loads, followed by the processing and handling of very large load case tables required for the analysis of floating wind turbines, down to time efficient post-processing of the analysis results compatible with typical commercial project schedules. The paper discusses some of the currently existing and applied methodologies on how the structural checks are typically performed in these circumstances, and addresses their advantages and shortcomings. In addition, a new Global Influence Superposition (GIS) methodology that has been developed by Ramboll is presented, which is able to address many of the existing challenges in an efficient manner.

Preliminary study of shear strain-based design approach for onshore wind turbine foundations

Different wind turbine foundation types were analyzed with PLAXIS 3D using a hardening/softening model with a small strain stiffness constitutive model to capture the characteristics of degradation of clays. The study found that even though the conventional design requirements were all satisfied, the shear strains under foundations varied greatly. A literature review regarding the shear strain versus soil degradation was performed, and relevant threshold strains that limit the soils to recoverable behaviors were discussed. A shear strain-based design approach was then proposed and a flowchart for the design process was presented for onshore wind turbine foundations. The proposed design approach simplifies the foundation designs under cyclic loads and relieves the concerns of cyclic degradation and the gapping issue of the foundations subjected to cyclic loads. The analysis results show the shear strains of soils could be effectively controlled within the small-strain threshold by using different structural dimensions, and sometimes together with geotechnical measures. The study found the widely used traditional gravity foundations are governed by conventional design requirements as the shear strains typically are smaller than the threshold level. However, the strain control criterion is dictating deep foundations used for wind turbines.