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A new approach based on the limit equilibrium method to calculate the ultimate bearing capacity of a strip shallow foundation is presented in this paper. The bearing capacity estimated with Terzaghi's three-term basic formula using the superposition method has proven to be conservative. A proposed failure mechanism to determine the bearing capacity coefficients of the three parameters, namely, the cohesion (Nc), the surface surcharge (Nq) and the soil weight (Nγ), is developed. The 'individual minimum' of each coefficient is determined using different failure mechanisms; hence, a new analytical approximation is suggested for calculating the 'global minimum' of the bearing capacity with a single failure mechanism without superposition. The rationality of the results of the analytical solutions (bearing capacity and failure mechanism) is verified using finite element analysis with the program PLAXIS 2D and kinematical analysis with the program FIDES-GeoStability. [ABSTRACT FROM AUTHOR]

The bearing capacity of shallow foundations is often calculated using the classical three-term bearing capacity equation, containing bearing capacity factors and correction factors for embedment depth and footing shape. The available solutions for the determination of these factors were obtained using primarily limit analysis and the method of characteristics, with the assumption that soil is a perfectly plastic material following an associated flow rule. However, in reality, sands are neither perfectly plastic nor do they follow an associated flow rule. The unit bearing capacity of footings in sand depends on (1) the representative friction angle mobilized within the zone encompassing the footing's collapse mechanism, and (2) the size, shape, and embedment depth of the footing. This paper presents the results of load tests on model strip and square footings of different sizes installed in clean silica sand samples pluviated to produce different densities inside a calibration chamber. The test results for the footings placed on the sand surface show that the bearing capacity factors depend on the relative density of the sand sample and the geometry of the footing. For the embedded footings, the unit bearing capacity of the footing is shown to depend on its embedment depth. Insights into the footing collapse mechanism are provided by plotting the maximum shear strain contours for different stages of footing loading; the contours were obtained using the digital image correlation technique. Finally, we determined the shape and depth factors by analyzing the results of the load tests performed for surface and embedded strip and square footings in dense sand using procedures that account for stress level, loading path, and flow rule nonassociativity. [ABSTRACT FROM AUTHOR]

The bearing capacity of shallow foundation is significantly affected by stratum uncertainty, mainly including geological uncertainty and spatial variability of soil properties. This paper aims to develop a general framework of shallow foundation to characterize the influence of two types of uncertainties on bearing capacity quantitatively. The geological uncertainty is simulated by Markov random field with different borehole schemes. The spatial variability is characterized using random field theory considering variations of the vertical scale of fluctuation. The bearing capacity of shallow foundation analysis is then conducted based on the proposed calculation framework. Borehole data and soil properties collected from Shenzhen Mawan are adopted as an example to illustrate the proposed framework. A reduction factor is developed to reveal the relationship of two category uncertainties on bearing capacity. A contribution rate indicator is defined to quantitatively evaluate the impact of two category uncertainties. Results show that the geological uncertainty greatly influences the calculation results when boreholes are sparse. However, spatial variability dominates in two kinds of uncertainties when having relatively more boreholes. [ABSTRACT FROM AUTHOR]

Analytical approaches to determine the long-term settlement of shallow foundations subjected to dynamic cyclic loading with a large number of cycles (millions) are presented. The approaches use the high-cycle accumulation (HCA) model to calculate the permanent strain caused by the cyclic loading and are conceptionally similar to conventional settlement analyses. The incorporation of a threshold strain amplitude, below which no accumulation of deformations occurs, in the HCA model is discussed. It is demonstrated that the simple analytical approach, which does not require numerical calculations, gives results very similar to more complex finite-element simulations. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of a vertical trench in mitigating the hazards associated with reverse faulting on shallow foundations and assesses the accuracy of analytical relations for estimating the required trench depth through numerical analyses. Results show that a trench near a foundation diverts the fault rupture away from the building. Increasing the trench depth and width, positioning it closer to the foundation, and increasing the structure weight significantly increase the fault rupture diversion probability, reducing foundation damage level. Moving the foundation towards the hanging wall decreases rupture diversion probability. Trenches are more effective at smaller fault-dip angles. Narrower foundations with deeper alluvium require shallower trenches to minimize foundation damage. Existing analytical relations estimate trench depth with reasonable accuracy to divert fault rupture and minimize structural damage. [ABSTRACT FROM AUTHOR]

Bio-cementation through microbially induced calcite precipitation (MICP) has the potential to overcome several technical and environmental limitations of conventional cement-based soil improvement techniques. While a significant amount of research has been directed towards better understanding and controlling MICP processes, there is still a lack of multiphysical formulations that can be used for the design of real geotechnical applications in which both the treatment extent and its strength and deformability need to be evaluated. This paper presents the development and application of a comprehensive bio-chemo-hydro-mechanical model that can be used for designing MICP treatments with the finite element method. To overcome the limitations of current approaches based on elasticity, the formulation involves an elastoplastic constitutive model based on Mohr–Coulomb that can predict the strength increase of MICP-improved soils. The model can easily be calibrated with existing experimental results. The scope of model application is demonstrated through the case of a 2D shallow foundation strengthening. Results reveal that the questions of what level of cementation to target and how to distribute cementation efficiently are of equal importance to ultimately serve the needs of specific geotechnical problems, such as those of bearing capacity. [ABSTRACT FROM AUTHOR]

The strength anisotropy and strain softening of natural soil can significantly impact the bearing capacity of shallow foundations on clay. In this article, we present a nonlocal numerical method to study the coupled rotation of the maximum normal stress axis and strain softening on the bearing capacity of shallow foundations on clay through a Cosserat strain softening constitutive model. The strength anisotropy and strain softening characteristics were numerically implemented into a finite-element (FE) program by dynamically updating the anisotropic cohesion in global Newton–Raphson iterations. Due to its nonlocal feature, the proposed nonlocal numerical method can overcome the mesh dependence in simulating the progressive failure of clay through the classical FE method. We first validated the efficacy of this method against the results of the plane strain test and numerical results in the literature. We then study the bearing capacity of a strip footing over anisotropic and strain-softening clay through the implemented numerical method. The results indicated that the deposition angle has an important effect on the bearing capacity and failure mode. The effects of the degree of anisotropy and strain softening on the ultimate bearing capacity are quantified through the numerical method. It is found that (1) the proposed method can effectively reflect the characteristics of the maximum normal stress axis rotation on the failure surface of the footing; (2) the ultimate bearing capacity of a footing (Pu) on anisotropic clay could increase linearly with an increase in the anisotropy ratio k (i.e., k is the ratio between C1 and C2) and decreases with an increase in the softening modulus; and (3) the strength anisotropy and strain softening are strongly coupling factors impacting the bearing capacity of anisotropic clay. [ABSTRACT FROM AUTHOR]

The significant rainfall in October 2018 in northern Iran caused devastating flooding that caused considerable economic losses and claimed at least nine lives. Following the flooding, several bridges have suffered different levels of damage. Immediately after the event, the authors conducted a field investigation to study the performance of RC bridges during the flood. This paper presents the failure modes of flood-affected bridges and provides reasons for every failure case. The results revealed that scour around foundations, pier tilting, flexural failure of piers, and superstructure unseating were the most significant failure modes observed. Pile-supported bridges performed notably better than those with shallow foundations. In addition, observations have revealed that structural integrity plays a crucial role in the general stability of bridges during flooding. Pier ductility is another significant parameter that affects the performance of bridges during flood events. Finally, fragility curves were developed based on the empirical data set provided from the post-flood status of the bridges in the affected region. The river flow velocity (Vs), maximum flow discharge (Qp), and Qp normalized to the 10-year average river discharge (Qm) were considered intensity measures of the fragility analysis. The correlation analyses revealed that despite Vs and Qp/Qm , the flow discharge was not an appropriate intensity measure for generating fragility curves. [ABSTRACT FROM AUTHOR]

The static stiffness of suction caisson foundations is an important engineering factor for offshore wind foundation design. However, existing simplified design models are mainly developed for nonlayered soil conditions, and their accuracy for layered soil conditions is uncertain. This creates a challenge for designing these foundations in offshore wind farm sites, where layered soil conditions are commonplace. To address this, this paper proposes a multifidelity data fusion approach that combines information from different physics-based models of varying accuracy, data sparsity, and computational costs in order to improve the accuracy of stiffness estimations for layered soil conditions. The results indicate that the proposed approach is more accurate than both the simplified design model and a single-fidelity machine learning model, even with limited training data. The proposed method offers a promising data-efficient solution for fast and robust stiffness estimations, which could lead to more cost-effective offshore foundation designs. [ABSTRACT FROM AUTHOR]

Water table elevation leads to saturation of the soil surrounding the foundation. Saturated soil loses its load-bearing capacity due to suction reduction, becoming less stable and more prone to settling. This phenomenon can result in differential settlement, leading to uneven stress distribution on the structure. Over the last few years, substantial research efforts have been dedicated to analyzing the bearing capacity of saturated reinforced sand when subjected to loading at the foundation center, with limited attention given to unsaturated reinforced sand under eccentric loading. Eccentric loading can also result in additional stresses and moments that need to be considered in the design of the foundation to ensure its long-term integrity and functionality, especially when subjected to wetting conditions. Hence, this study investigated this aspect experimentally and numerically using the discrete element method (DEM) to uncover the intricate interactions between soil-reinforcement conditions, applied stress, and wetting-induced settlement. The results reveal that the geosynthetic reinforcement influences the extent of collapse settlement. While the reinforcement reduces collapse settlement, the enhancement is particularly notable when subjected to eccentric loadings. For both semisaturated and fully saturated conditions, the bearing capacity ratio (BCR) not only increases with the number of geosynthetic layers but also exhibits a higher rate for fully saturated sand than for the dry and semisaturated states. Unlike unreinforced sand where load eccentricity increases collapse settlement and differential settlement, reinforced sand experiences reduced settlement as load eccentricity increases. Finally, an empirical relationship by assessing the effect of the interface between the soil and the reinforcement layer was derived from regression analyses to predict the eccentric bearing capacity of strip footing under conditions of upward seepage. Practical Applications: Alterations in pore-water pressure can influence the bearing capacity of shallow foundations. When the ground beneath a foundation reaches complete saturation, the in situ stresses that usually act as confining pressure experience an abrupt decrease. This phenomenon can induce additional settlements, which is very critical in foundation design applications, especially for foundations with eccentric loading, e.g., foundations subjected to wind load. Many shallow foundations are rested on deposits in coastal regions and along riverbanks. The failure due to the accumulation of pore-water pressure occurs when the shear stress applied by the superstructure surpasses the shear strength of the compromised soil. However, in cases where failure does not emerge, there remain issues related to serviceability and the potential for excessive settlement. This research demonstrates that the geosynthetic layers not only enhance the bearing capacity of strip footing but also show a greater improvement for eccentrically loadings in fully saturated sand compared to dry and semisaturated states. [ABSTRACT FROM AUTHOR]

Over the last few decades, reliability-based design methods have been widely implemented into the foundation design practice. However, several design codes for transmission tower foundations are still based on the allowable stress design (ASD) approach and are yet to adopt the reliability-based approach for design. This paper developed a load and resistance factor design (LRFD) method based on an existing ASD code to design spread foundations of transmission towers under uplift loading in cohesionless soils. In the LRFD development procedures, additional analysis was carried out to check the statistically significant dependency of the model factors (i.e., the ratio between the measured and calculated foundation capacities) on the foundation design parameters. The analysis results showed that there were statistical dependencies between the model factors and the foundation width, which are known as scale effects. By incorporating the identified dependencies, reliability analysis was carried out via Monte Carlo simulations (MCS) by considering the context of transmission tower foundations. From the reliability analysis outputs, it was found that the foundation width had notable effects on the foundation reliability and the calibrated resistance factors. The LRFD format of the existing code was proposed, along with the resistance factors for varying foundation widths and target reliability indices. Finally, a design example was illustrated to compare the design uplift capacities from the existing ASD format and the proposed LRFD format of the design code. Compared to the existing code, the developed LRFD method showed significant improvements in the consistency of the design capacities and the associated reliability levels for a given foundation design. [ABSTRACT FROM AUTHOR]

The foundation ring (FR) is a steel component embedded within the concrete of a wind turbine foundation, playing a pivotal role in connecting the wind turbine tower to the foundation structure. In this paper, the FR–foundation connection is equivalent to the exposed foundation and the shallow foundation by analyzing the anchorage characteristics of the foundation ring. Based on the ABAQUS concrete damaged plasticity model, full-scale modeling of the wind turbine foundation is carried out. The influence of embedment depth, ring radius and base flange width of the foundation ring on moment capacity is simulated. Based on the observed stress distributions under ultimate loads, analytical expressions were proposed to estimate the variation law of anchorage load-bearing capacity in the ultimate load state. Compared with the numerical simulation, the average errors under different influencing factors are 8.2%, 9.6% and 10.8%, respectively. The results indicate that the base flange provided the majority of the moment capacity, though the contribution of the sidewall increased to 25–50% that of the base flange in later stages. [ABSTRACT FROM AUTHOR]

This paper proposes a semi‐analytical solution for the ultimate bearing capacity qu of both smooth and rough circular shallow foundations on rock mass. Specifically, a three‐dimensional (3D) Hoek–Brown (HB) is adopted, in conjunction with equilibrium equations under axisymmetric conditions, to derive the governing equations. The method of characteristics is utilized to solve the stress and failure characteristics mesh to determine the qu. The proposed solution is verified by using it to analyze test foundations. Comparison with an HB criterion‐based solution is performed to highlight the importance of 3D strength. Furthermore, parametric studies are performed to investigate the effects of rock mass properties (intact rock constant mi${m}_{\mathrm{i}}$, geological strength index GSI, intact rock unconfined compressive strength σc) and foundation diameter (B) on the qu, failure surface size, and vertical stress distribution on the foundation base. The results indicate that ignoring the 3D strength and the rock mass weight would lead to underestimation of qu. Besides, the ultimate bearing capacity factor Nσ${N}_{{\sigma}}$ (ratio of qu to σc) increases with mi${m}_{\mathrm{i}}$, GSI and B but decreases with σc${\sigma }_{\mathrm{c}}$. The failure surface size is significantly affected by mi${m}_{\mathrm{i}}$, GSI, B, σc${\sigma }_{\mathrm{c}}$ and rock mass unit weight. The stress distribution on the foundation base has higher variance (higher possibility of stress concentration) at smaller σc${\sigma }_{\mathrm{c}}$, GSI, and larger B, rock mass unit weight. [ABSTRACT FROM AUTHOR]

Analyzing the stability of footings is a significant step in civil/geotechnical engineering projects. In this work, two novel predictive tools are suggested based on an artificial neural network (ANN) to analyze the bearing capacity of a footing installed on a two-layered soil mass. To this end, backtracking search algorithm (BSA) and equilibrium optimizer (EO) are employed to train the ANN for approximating the stability value (SV) of the system. After executing a set of finite element analyses, the settlement values lower/higher than 5 cm are considered to indicate the stability/failure of the system. The results demonstrated the efficiency of these algorithms in fulfilling the assigned task. In detail, the training error of the ANN (in terms of root mean square error—RMSE)) dropped from 0.3585 to 0.3165 (11.72%) and 0.2959 (17.46%) by applying the BSA and EO, respectively. Moreover, the prediction accuracy of the ANN climbed from 93.7 to 94.3% and 94.1% (in terms of area under the receiving operating characteristics curve—AUROC). A comparison between the elite complexities of these algorithms showed that the EO enjoys a larger accuracy, while BSA is a more time-effective optimizer. Lastly, an explicit mathematical formula is derived from the EO-ANN model to be conveniently used in predicting the SV. [ABSTRACT FROM AUTHOR]

This study investigates the ultimate bearing capacity (UBC) of an eccentrically loaded strip footing of width, B, resting above circular dual cavities in the rock mass using the Generalized Hoek–Brown (GHB) yield criteria for the rock mass. The stability number (Ns) is determined using upper and lower-bound finite element limit analysis (FELA), incorporating an adaptive meshing technique. The study considers two configurations: symmetrical and parallel outlines based on the relative positions of the dual cavities and the footing. The effects of the numerous governing parameters, including the load eccentricity (e/B), the vertical distance of dual cavities from the ground surface (δ/B), the spacing between dual cavities (β/B), the uniaxial compressive strength of intact rock, ( σ ci /γB), geological strength index (GSI), and material constant for intact rock (mi) on the Ns are studied. The study finds that the magnitude of e/B significantly affects Ns. For symmetrical outline, Ns improves with increasing δ/B, and the effect of δ/B is insignificant when δ/B ≥ 3, corresponding to β/B = 4 irrespective of e/B. Moreover, Ns increases with β/B for δ/B ≤ 3 and e/B ≤ 0.2. However, the effect of β/B on Ns is insignificant beyond δ/B > 3, irrespective of e/B. For the parallel outline case, the strip footing achieves maximum Ns under centrally placed load (i.e., e/B = 0), regardless of β/B and δ/B values. The study presents potential failure envelopes that might include all representative cases to provide insights into the possible failure mechanism of such foundation systems. [ABSTRACT FROM AUTHOR]

Fully coupled soil–structure analyses were performed for a building of strategic importance located in the city of Messina (Sicily, Italy). The structure was built after the destructive 1908 earthquake, also known as the 'Messina and Reggio Calabria earthquake', which caused severe ground shaking. A parametric study considering three seismograms of this earthquake was performed. Deep in situ and laboratory investigations allowed the definition of the geometric and geotechnical model of the subsoil. Numerical analyses were performed with PLAXIS3D finite element software (Version 21.01.00.479). The Hardening Soil model with small-strain stiffness was accurately calibrated using laboratory and field data. The dynamic response was investigated in terms of accelerations, response spectra, amplification functions, displacements and stress–strain hysteretic loops. The findings show that many aspects must be investigated for the retrofitting of buildings with shallow foundation in areas characterized by a medium to high level of seismic risk: (i) a key role is played by an accurate investigation of the soil; taking into account the specific conditions of the soil, it was possible to investigate its filtering effects; (ii) the dynamic response of the fully-coupled soil–structure system deviates from the free field-site response analysis; (iii) the results reveal the importance of considering the soil nonlinearity in seismic soil–structure interaction problems. [ABSTRACT FROM AUTHOR]

This paper investigates the interference effect of closely spaced foundations on the modulus of subgrade reaction (k) and provides an insight into some of the factors affecting the k-value of a raft foundation when other foundations (isolated footings or other identical rafts) are closely placed on both sides. The investigation adopted a three-dimensional, non-linear, finite-element numerical analysis based on a case study of a residential project with several multi-storey buildings constructed on sand underlain by weathered limestone. A site-specific ground investigation was conducted to determine soil properties, which were used to construct three-dimensional numerical models to simulate different arrangements of foundations and estimate the corresponding k-values. The results show that the k-value starts to decrease when the spacing between the foundations becomes less than three times the raft width, and the percentage of reduction in k-value increases in a non-linear way as the spacing decreases further. In addition to spacing, the study revealed that the effect of adjacent foundations depends on their size and the magnitude of their applied pressure. The case study provides a framework for developing a correction factor that can be applied to k-value for improving the structural and geotechnical design of closely spaced shallow foundations. [ABSTRACT FROM AUTHOR]

In many settlement prediction methods, the creep settlement of shallow foundations on sand is either disregarded or accounted for using time correction factors that lack a reliable basis. These existing settlement correction factors for creep have mainly been derived from a restricted number of long-term settlement measurements and do not consider the influence of factors such as the load level, rate of load application and properties of the soil below the foundation. In this study, a newly proposed one-dimensional elasto-viscoplastic macro-element was used to investigate the factors influencing the time-dependent behaviour of shallow foundations on sand. The safety factor of the foundation, the creep characteristics of the soils and the duration of load application were found to have important effects on the post-construction settlement development. The simulation results were used to develop an enhanced settlement correction factor for creep, which takes into account the identified factors. The improved settlement correction factor was found to be comparable to existing ones when the safety factor of the foundation is 3. The effectiveness of the proposed settlement correction factor is demonstrated using creep settlement measurements from one field footing test and two case histories. [ABSTRACT FROM AUTHOR]

This study aims to determine the capacity of surface soils, the loading layers of engineered structures with shallow foundations, to swell. For this, five samples were collected using a hand auger at a depth of 1.5–2 meters in the city of Al-Faw in Basra, Iraq. The swelling potential of the soils in the research area was calculated using the clay content, liquid limit, plasticity index, and shrinkage limit values, and the constituent minerals were identified using X-ray diffraction. According to the results of the Atterberg’s limit tests, the soil samples taken from the city of Al-Faw fall into one of three categories: clayey silt low plasticity (ML), clay high plasticity (CH), or silty clay low plasticity (CL). The liquid limit in soil samples ranges between 34-55%, and the plasticity index values range between 12 and 28%. Three samples are of medium swelling potential, while the third location has high swelling potential and the second location has low swelling potential, and the X-ray diffraction data demonstrate that Montmorillonite is the main dominant clay mineral, accounting for an average of 31.88%, followed by Kaolinite mineral, which accounts for an average of 28.984%, Illite, which accounts for an average of 19.5702%, Chlorite, which accounts for an average of 12.1864%, and Palegorskite, which accounts for an average of 7.3688%. [ABSTRACT FROM AUTHOR]

Offshore oil and gas exploration activities involve the installation of various subsea infrastructures on the ocean floor, often supported by shallow foundations such as anchor plates or mudmats. These foundations must be designed to withstand applied service loads along the structure lifecycle, including decommissioning loads required for subsequent removal. In this context, this work is dedicated to the evaluation of uplift bearing capacity of shallow anchors within the theoretical framework of limit analysis and its related kinematic approach. Based on the implementation of 3D failure mechanisms, rigorous upper bound estimates for the uplift force viewed as ultimate load for the material system are derived from either total or effective stress analyses. In that respect, emphasis is given to the formulation of limit analysis problem in the context of effective stresses, showing how the effect of seepage flow may be accounted for by means of driving body forces derived from the gradient of excess pore pressure distribution and how suction forces arise from pore pressure difference between upper and lower anchor surfaces. Evaluation of suction forces developed during anchor lifting is addressed by resorting to a simplified modeling applied to circular and rectangular anchors. The accuracy of the upper bound predictions derived for uplift force is assessed by comparison with available experimental data. Several numerical results are also provided to investigate the effects of relevant problem parameters on the uplift bearing capacity. [ABSTRACT FROM AUTHOR]

This paper presents a mechanical analysis of the foundation of a temporary offshore platform using a temporary embedded eight-leg support structure. The model is simulated using the finite element simulation software MIDAS-3D, with the modified RANS equation and Forchheimer saturated resistance model used to control the fluid. The stress analysis principle of the structure is simplified by the pile group theory. The stability of the eight-legged supporting structure is investigated under different embedding depths, pile diameters, wave periods, and amplitudes of the main piles. The results show that the eight-legged supporting structure can intercept and divert water flow, eliminating the impact of the water flow on the main piles during large waves. Additionally, as the diameter of the structure increases under the same wave conditions, the influence of the base volume and surface curvature gradually increases, deteriorating the stress environment of the main pile and decreasing the supporting effect of the eight-legged support structure. Numerical calculations of the seabed rock foundation of the eight-leg supporting structure show that the shallow pile foundation undergoes significant deformation, while the eight-leg supporting structure is still supported by the dead weight of the main pile. [ABSTRACT FROM AUTHOR]

With the shift of the offshore wind energy sector to deeper waters, demand for the development of more complex foundation solutions, particularly suction bucket – supported tripod/tetrapod and jacket foundations, has increased. This paper is divided into two main sections. The first part comprises a comprehensive review of the performance of circular surface and shallow foundations under combined loading (VHM), and how it can principally be understood in a theoretical framework of plasticity theory. Examination of the considered data suggested that the general assumption of over‐estimated non‐association degree with constant failure surface parameters and increasing vertical load may require further investigation. This may be attributed to the complex interplay of multiple properties such as stress level, soil strength profile and foundation geometry. The existing data in the literature were also used to provide practical guidance for a successful implementation of the elasto‐plastic constitutive relationships in offshore foundation design. In second part of the paper, the suitability of the non‐associated plasticity formulation for a baseline multi‐pod system in H‐M load space was investigated using three‐dimensional (3D) finite element (FE) analyses and not verified. Furthermore, the failure envelopes and hardening law for caissons with different embedment ratios differed from those recommended in the literature were established. Parametric studies of multi‐caisson foundations revealed that the failure mechanism of multi‐bucket foundations under horizontal loading depended greatly on the bucket spacing. The horizontal bearing capacities increased with the bucket spacing until they reached a threshold. Meanwhile, analyses of the multi‐bucket foundation under moment loading confirmed the occurrence of a push‐pull failure mechanism. [ABSTRACT FROM AUTHOR]

The present study focuses on estimating the transient response of shallow strip footing on granular soil using soft computing techniques. A shallow foundation is numerically modelled using Beam on Nonlinear Winkler Foundation model. Then the footing is subjected to a combination of allowable static and cyclic load depending on the ultimate bearing capacity of the footing. The eccentricity and angle of load inclination of static load are varied to simulate more practical conditions. The cyclic load is rectangular pulse load. One cycle of rectangular pulse load is applied to observe the immediate response of the foundation, referred as the transient response. Apart from the loading parameters, three granular soils of three different relative densities (Dr = 35%, 51% and 69%) are considered. Based on numerical simulation of 1728 conditions, soft computing models are developed using five techniques, viz. Neural Networks, Support Vector Machines, Multivariate Adaptive Regression Splines, Adaptive Neuro Fuzzy Interface System and Multi Gene Genetic Programming. It is found that the static load on the foundation is the most important parameter controlling the transient response of the footing. [ABSTRACT FROM AUTHOR]

Anchored wire meshes are commonly adopted to stabilize potentially unstable soil slopes. This reinforcement technique, employed either as an active or a passive anchoring system, is commonly designed according to ultimate limit state approaches. In this paper, an interaction model, useful for the design of anchored wire meshes, is proposed. The model is based on the results of a series of 3D large displacement finite element numerical analyses, in which the wire mesh mechanical behaviour is modelled as either an elastic or an elastic–plastic membrane. The model is inspired to standard load–displacement curves for shallow foundations, and the wire mesh presence is taken into account by suitably modifying the bearing capacity formula. The proposed model predictions are compared with experimental punching test results. The use of the model, only requiring the definition of geometry and soil–wire mesh mechanical properties, allows the pre-design of the reinforcement system without performing ad hoc finite element numerical analyses. [ABSTRACT FROM AUTHOR]

With the shift of the offshore wind energy sector to deeper waters, demand for the development of more complex foundation solutions, particularly suction bucket – supported tripod/tetrapod and jacket foundations, has increased. This paper is divided into two main sections. The first part comprises a comprehensive review of the performance of circular surface and shallow foundations under combined loading (VHM), and how it can principally be understood in a theoretical framework of plasticity theory. Examination of the considered data suggested that the general assumption of over‐estimated non‐association degree with constant failure surface parameters and increasing vertical load may require further investigation. This may be attributed to the complex interplay of multiple properties such as stress level, soil strength profile and foundation geometry. The existing data in the literature were also used to provide practical guidance for a successful implementation of the elasto‐plastic constitutive relationships in offshore foundation design. In second part of the paper, the suitability of the non‐associated plasticity formulation for a baseline multi‐pod system in H‐M load space was investigated using three‐dimensional (3D) finite element (FE) analyses and not verified. Furthermore, the failure envelopes and hardening law for caissons with different embedment ratios differed from those recommended in the literature were established. Parametric studies of multi‐caisson foundations revealed that the failure mechanism of multi‐bucket foundations under horizontal loading depended greatly on the bucket spacing. The horizontal bearing capacities increased with the bucket spacing until they reached a threshold. Meanwhile, analyses of the multi‐bucket foundation under moment loading confirmed the occurrence of a push‐pull failure mechanism. [ABSTRACT FROM AUTHOR]

Tracked vehicles are widely deployed for heavy lifting and transportation on inaccessible terrains such as swamps, bogs, and peatlands. The stability of a tracked vehicle is traditionally assessed only under uniaxial loading conditions and the impact of combined loading from different directions is ignored. This makes the conventional design framework somewhat unreliable. The failure envelope approach has been widely employed to assess the load-carrying capacity of shallow foundations. However, the failure envelopes available in public domain mainly focused on single isolated foundations, ignoring the interference effect between the tracks due to the rigid connection of the vehicle. This paper aims to develop an integrated framework to assess the stability of a tracked vehicle on a soft soil under fully three-dimensional loading conditions. The finite element method is adopted to simulate the soil–vehicle interactions, with the tracks idealised as two shallow foundations in parallel. The stability of the foundation system is described in terms of failure envelopes considering various track configurations and load combinations. Failure envelopes are represented by expressions and ultimately integrated into a multiple-nested function to determine the overall stability factor. The framework is demonstrated by a case study of designing a tracked vehicle under combined loading conditions. [ABSTRACT FROM AUTHOR]

This study focuses on the field reconnaissance efforts for investigating ground deformation behavior and building foundation performance in Iskenderun. Many structures experienced significant damage or collapsed due to strong ground shaking in the coastal Iskenderun district of Hatay during the 2023 Kahramanmaras earthquake sequence. Many buildings were also impacted by ground failure due to liquefaction of deposits in the area. Preliminary information regarding the general subsurface profile and post-earthquake data collected during the reconnaissance was used to perform simplified liquefaction and lateral spreading analyses. The empirical methods provide first order estimations of settlements and lateral spreading but are not sufficient when the nature of the structure-soil-structure interaction and earthquake sequence is considered. Measurements of vertical displacements and building tilt, liquefaction manifestations, and structural and foundation parameters potentially affecting foundation settlements including foundation geometry, building contact pressure, and building elastic period were used to evaluate seismic response of the ground and the structures through empirical procedures. Most of the buildings exhibited poor to mediocre foundation performance due to liquefaction-prone subsurface profiles, especially on the coastline. Ongoing field and numerical research will reveal the cause of significant ground failure in the area as well as refined estimates for the seismic deformations. [ABSTRACT FROM AUTHOR]

An integrated geophysical survey using land magnetic and ground penetrating radar (GPR) methods was conducted to investigate the archaeological findings and ancient cultural relics at an undiscovered 100 m × 60 m in Tal-Baltus in El-Sadat city, Menofia Governorate, Egypt. The study area at Tal-Baltus was chosen among several archaeological hills in the Menofia governorate due to its archaeological significance in the Greco-Roman history of Egypt. The total area was first surveyed using the magnetic method, and then two small promising sites within this area were selected for the GPR survey. The obtained magnetic results showed the presence of remarkably high anomalies with different shapes of irregular geometry. Therefore, they are interpreted as ruins of old storage rooms related to an ancient harbor-shaped structure. Besides, numerous scattered pillars and column heads were also delineated and matched with remains of granite blocks in abundance in the study area, taking the same trend as the delineated magnetic anomalies. In addition, the GPR results highlighted several hyperbolas with variable amplitudes and sizes, which have been interpreted as the shallow foundation of a potential ancient harbor made of limestone. The comprehensive interpretation of the integrated magnetic and GPR surveys strongly suggests that the study area may be a part of an ancient harbor in addition to some other ancillary room-shaped structures used for cargo storage purposes and scattered portions of walls and pillars dating back to the Greco-Roman era. [ABSTRACT FROM AUTHOR]

This study examines the potential of the soft computing technique, namely, multiple linear regression (MLR), genetic programming (GP), classification and regression trees (CART) and GA-ENN (genetic algorithm-emotional neuron network), to predict the ultimate bearing capacity (UBC) of cohesionless soils beneath shallow foundations. For the first time, two grey-box AI models, GP and CART, and one hybrid AI model, GA-ENN, were used in the literature to predict UBC. The inputs of the model are the width of footing (B), depth of footing (D), footing geometry (ratio of length to width, L/B), unit weight of sand (γd or γ′), and internal friction angle (ϕ). The results of the present model were compared with those obtained via two theoretical approaches and one AI approach reported in the literature. The statistical evaluation of results shows that the presently applied paradigm is better than the theoretical approaches and is competing well for the prediction of qu. This study shows that the developed AI models are a robust model for the qu prediction of shallow foundations on cohesionless soil. Sensitivity analysis was also carried out to determine the effect of each input parameter. The findings showed that the width and depth of the foundation and unit weight of soil (γd or γ′) played the most significant roles, while the internal friction angle and L/B showed less importance in predicting qu. [ABSTRACT FROM AUTHOR]

The paper analyses in detail and compares different interpretation procedures of snap-back and forced-vibration tests on a full-scale prototype founded on soft-soil, in order to assess their effectiveness for measuring the stiffness and damping of a shallow foundation under dynamic loads. Both properties were back-calculated through three alternative methods, i.e. through impedance functions computed in the frequency domain, or by interpreting force-displacement loops in terms of peak-to-peak amplitudes or of phase-shift. The damping was further calculated from the logarithmic decrement of free-vibration records. The resulting foundation stiffness and damping were observed to vary with the number of cycles and with the load frequency and amplitude. The comparison among the interpretation techniques revealed that the peak-to-peak approach fails when damping is high, because it neglects the delay between force and displacement. [ABSTRACT FROM AUTHOR]

Reasonable determination of the ultimate bearing capacity of the foundation is of great significance in engineering applications. Based on the self-developed non-contact testing device for the plastic zone of shallow foundation, this paper carries out model test research on the plastic zone of sandy soil shallow foundation and analyzes the development law of plastic zone under the action of foundation load. The main advantages and functional characteristics of the foundation plastic zone test system are that it can realize the non-contact test of displacement deformation of soil, the dynamic development process of shear deformation, and the plastic zone of model foundation can be obtained intuitively. The development process, morphological boundary characteristics, and foundation failure mode of the plastic zone of the sand foundation are obtained. The plastic zone of the foundation starts from the edges of both sides of the bearing plate; with the increase of the load, the plastic zone gradually develops downward and approaches to the center line, and finally crosses through at the bottom until the local shear failure of the foundation occurs. The measured plastic zone is a symmetrical spindle shape with thin ends and a bulge in the middle; the sand on both sides of the bearing plate partially bulges, forming a "V" shaped shear failure zone, and the bottom of bearing plate forms a triangular compression zone, the foundation failure mode of sandy soil represents a typical punching shear failure mode. In order to study the distribution characteristics of the plastic zone range of foundation under different foundation loads and foundation widths, the Universal Distinct Element Code (UDEC) based on the discrete element method is used for numerical simulation research. By conducting parameterized numerical simulation test for the plastic zone of foundation and analyzing the results, with the changes in the foundation load and the foundation width, the variation law of (1) the depth of the plastic zone on the foundation bottom, (2) the width of the plastic zone on both sides of the foundation, (3) the ratio for the depth of plastic zone to the width of foundation, (4) the ratio for the width of plastic zone to the width of foundation and (5) the ratio for the width of plastic zone to the depth of plastic zone is obtained. The research has significant guiding significance for the study of the development law of plastic zone and foundation design. [ABSTRACT FROM AUTHOR]

The Lanolin 750 kV electrical transmission line traverses more than 102.86 km through seasonally frozen regions, causing many engineering problems for transmission tower foundations. In this work, physical models of reinforced concrete independent foundations in soils with different frost heave grades were used to simulate the frost heaving performance in seasonally frozen alpine regions. The test results were used to evaluate the tangential frost heaving force calculated based on different specifications. The results showed that the tangential frost heaving force and frozen depth increased with the temperature decrease. Moderately frost-susceptible soils also increased the tangential frost heaving force and frozen depth. Based on technical standards, the main differences between the calculated and the test values were the variable load component and effective frozen depth coefficients. Correcting the coefficient values resulted in a closer agreement between the test and the calculation results. [ABSTRACT FROM AUTHOR]

This paper utilized an advanced surrogate modeling technique known as adaptive kriging (AK) for the probabilistic design of foundations. The quantile-based approach accounted for the variability in soil and foundation dimensions with an adequate level of safety, and the AK algorithm replaced the theoretical or numerical models with surrogate models to improve the computational efficiency. The AK model had the advantage of considering the design dimensions and their variability in its optimization algorithm. For the design of shallow foundations, the variability in the design dimensions and its optimization was carried out by introducing the width-to-length ratio as the design parameter. This meant that a surrogate model for different foundation dimensions did not need to be developed separately. This paper showed that the computational time for the AK model was much less compared with the probabilistic analysis that used numerical models. A quantile-based design and optimization procedure that used the AK model was illustrated through a shallow foundation example and provided economical design parameters. [ABSTRACT FROM AUTHOR]

This research investigates the influence of the scale effect on the bearing capacity of fine-grained subsoil under undrained conditions. The analyses were conducted based on laboratory tests of silty clay. Uniformly compacted samples were subjected to an unconfined compression test. The research was performed on cylindrical specimens. Three different variants of the diameter D (38 mm, 70 mm, 100 mm) and the corresponding height H = 2D were analyzed. Based on the tests results, the unconfined compression strength qu was determined, and from this, the undrained shear strength cu was calculated. The obtained results showed a clear decrease in cu with increasing sample size. However, in the existing reference documents, there are no specific guidelines for calculations of bearing capacity with consideration of sample size effect on the soil shear strength. Therefore, this study utilized the laboratory soil test data to calculate the bearing capacity of undrained subsoil, taking into account the seismic impacts, with a particular focus on spread foundations. [ABSTRACT FROM AUTHOR]

Stone columns are widely used around the world as cost-effective soil improvement techniques for highways and embankments. They are also used as drainage to expedite the consolidation period, and accordingly to increase the allowable pressure, reduce settlement, and reduce the liquefaction potential for shallow foundations. Currently the design of these columns is based on the unit cell or homogenised material concepts, which neglect the effect of the interaction of the columns. This paper presents a 3-D numerical model using the finite element technique and the commercial software 'ABAQUS' to simulate the case of a group of stone columns installed in soft clay. The model is capable of capturing the interaction between columns and the surrounding soil and of establishing the mode of failure of the system. After validating the model with the available experimental results, it was used to predict the allowable pressure and the failure mechanism of groups of stone columns for given geometry/soil conditions. An improvement factor was introduced 'IF', which is defined as the ratio of the capacity of the improved to the unimproved soft clay. The results of this investigation are presented in the form of design charts to assist the engineer to determine the level of improvement needed to achieve a given allowable pressure for the foundation. [ABSTRACT FROM AUTHOR]

Shake table experiments are conducted to assess the potential of the polymer injection technique as a liquefaction countermeasure. A large 2.9 m high (10 ft) laminar soil container on a 3.9×1.85 m (13×6 ft) shake table is employed. Mitigation of liquefaction-induced settlement for a shallow foundation is explored. In a series of two shake table experiments, the system response is studied first without (baseline) and subsequently with polymer injected into the liquefiable stratum. Each test is densely instrumented to provide insights into the dynamic response of the soil and foundation system. Furthermore, cone penetration tests (CPTs) are performed pre- and postinjection to assess the extent of soil improvement. Strong base excitation is imparted by the shake table, resulting in liquefaction and excessive foundation settlement in the original baseline test. In the second test, with the polymer injection countermeasure, a significant reduction is observed in the tendency for liquefaction and the resulting foundation settlement. After this test, careful excavation provided additional insights into the polymer's configuration within the deposit, increasing overall soil relative density, confinement and creating solidified paths for the shallow foundation load toward the lower, more competent stratum. As such, these mechanisms have the potential to allow for: (1) an increase in soil resistance to liquefaction, and (2) a significant reduction in settlement of overlying shallow foundations. [ABSTRACT FROM AUTHOR]

This research analyzed the role of footing aspect ratio in influencing the limit bearing capacity and associated failure mechanism in saturated, structured clays. The effects of footing aspect ratio and footing–soil interface conditions on the extent of soil destructuration, during mobilization of limit load, were investigated using advanced finite-element analyses. These analyses employed a clay constitutive model that accounted for continuous load-induced evolutions of soil destructuration and stress-induced anisotropy. The soil destructuration process caused 30%–35% reduction in the limit bearing capacity of shallow foundations. Moreover, the proposed analysis-based shape factor for footings in structured clay suggests that the use of shape factors available in the literature would overpredict the limit bearing capacity for footings in clays prone to destructuration. [ABSTRACT FROM AUTHOR]

This paper investigates probabilistic failure envelopes of strip foundations on spatially variable soils with profiles of undrained shear strength, su, linearly increasing with depth using lower-bound random finite-element limit analysis. The spatially variable su is characterised by a non-stationary random field with linearly increasing mean and constant coefficient of variation (COV) with depth. The deterministic uniaxial capacities and failure envelopes are first derived to validate the numerical models and provide a reference for the subsequent probabilistic analysis. Results indicate that the random field parameters COVsu (the COV of su) and Δ (dimensionless autocorrelation distance) have a considerable effect on the probabilistic normalised uniaxial capacities, which alters the size of the probabilistic failure envelopes. However, an insignificant effect of COVsu and Δ on the shape of probabilistic failure envelopes is observed in the V–H, V–M and H–M loading spaces, such that failure envelopes for different soil variabilities can be simply scaled by the uniaxial capacities. In contrast to COVsu and Δ, the soil strength heterogeneity index κ = μkB/μsu0 has the lowest effect on the probabilistic normalised uniaxial capacity factors, but the highest effect on the shape of the probabilistic failure envelopes. A series of expressions is proposed to describe the shape of deterministic and probabilistic failure envelopes for strip foundations under combined vertical, horizontal and moment (V–H–M) loading. [ABSTRACT FROM AUTHOR]

Based on the geological conditions of the anchorage for a suspension bridge, it is proposed to calculate the value with theoretical methods. The Hoek-Brown solution, Bell solution and the modified Hoek-Brown solution are respectively used for comparative analysis based on the side loading effect of overlying rock and soil within the buried depth of the foundation base and the confining pressure effect of surrounding rock mass in the passive area, so as to obtain the theoretical solution of the bearing capacity of the bearing stratum of the project. In order to evaluate the difference between the above-mentioned standard solutions and the theoretical solutions and the measured values, a total of 6 groups of bearing capacity measurement tests in the bearing stratum of deep rock mass were carried out based on the East and West anchorage sites of the suspension bridge. The test results show that the characteristic value of the bearing capacity of the moderately weathered mudstone in the West anchorage and the characteristic value of the bearing capacity of the moderately weathered argillaceous sandstone in the East anchorage of the bridge are 2131 kPa and 2461 kPa respectively, which are significantly higher than the recommended value calculated according to the shallow foundation method in the current specification, and are closer to the modified Hoek-Brown theoretical solution, which provides a reference for the design and value selection for the bearing capacity of the bearing stratum of similar projects. [ABSTRACT FROM AUTHOR]

This paper presents three-dimensional finite element analyses conducted to optimise the instrumentation plan for monitoring the structural performance of reinforced concrete three-sided culverts (TSCs). Numerical models were developed for three TSCs with spans of 7.3, 10.4, and 13.5 m to establish the anticipated range of measurements. The TSCs were instrumented with 30 pressure cells and 56 strain gauges. Comparing the numerical predictions with field measurements of the 10.4-m-span TSC verified the adequacy of simulating the concrete behaviour as linear elastic for estimating the applied earth pressures. However, such simplification would lead to underestimating the induced strains in the culvert body in case cracks develop. In addition, Class-A predictions of soil pressures on the culvert were compared with the field measurements of a 7.3-m-span TSC. The calculated soil pressures agreed well with the field measurements. The measured and calculated earth pressures suggest a vertical arching factor of 1.05 at the final backfill height. The influence of the shallow foundation geometry was investigated employing the validated numerical model. It was found that the footing geometry has no influence on the applied earth pressures. However, the calculated stresses below the footing edge on the backfill side decreased as the footing flexibility increased. [ABSTRACT FROM AUTHOR]

Geotechnical Seismic Isolation (GSI) is an innovative technique for protecting structures in earthquake-prone areas. The main idea is to improve the foundation soil so that seismic energy is partially dissipated within GSI before being transmitted to the structure. Among other materials proposed for foundation soil improvement, gravel-rubber mixtures (GRMs), with rubber grains manufactured from end-of-life tires, have attracted significant research interest thanks to their good mechanical properties. GRMs also represent a modern recycling system to reduce the stockpile of scrap tires worldwide. The present study investigated numerically the effect of a GRM layer located underneath the shallow foundations of a real structure. The structure is a typical reinforced concrete building in southern Italy. A Finite Element Modelling (FEM) was carried out to evaluate the overall static and dynamic behaviour of the soil-GRMs-structure system. Three FEM models were performed with and without the GRM layer, varying the GRM layer thickness and the seismic inputs. The comparisons among the models allow us to assess the performance of the GRM underneath the foundations as a new eco-sustainable solution for the seismic isolation of structures. [ABSTRACT FROM AUTHOR]

The method employed in this study combines large-scale shaking table tests with fully coupled 3D non-linear dynamic analysis to investigate the site response and structural damage mechanisms of laterally spreading site cluster pile foundation systems under weak and strong seismic excitation. The study also aims to verify the applicability of the high-efficiency and universal parallel calculation system method, which involves SolidWorks, HyperMesh, OpenSeesMP, and GiD, with a fully visualized interface operation in geotechnical engineering, based on the test database. The results show that under weak seismic excitation, the acceleration and displacement in the free field and near-pile region are linearly distributed along the burial depth, and the motion of shallow pile foundation is mainly controlled by the inertial effect of the superstructure; while under strong seismic excitation, the displacement in the near-field region is much smaller than the free field showing significant pile pinning effect, and the displacement and acceleration in the near-pile domain are cosine-shaped distributed along the burial depth, with the lateral spreading of site liquefaction intensifying. At the intersection of clay and sand layers, a weak interlayer is present, which affects the structural response. The kinematic effect of the site dominates the response, and the location of vulnerability gradually shifts from the pile bottom to the pile head. [ABSTRACT FROM AUTHOR]

The complexity of the cohesive soil structure necessitates settlement modeling beneath shallow foundations. The goal of this research is to use recently discovered machine learning techniques called the hybridized radial basis function neural network (RBFNN) with sine cosine algorithm (SCA) and firefly algorithm (FFA) to detect settlement (Sm) of shallow foundations. The purpose of using optimization methods was to find the optimal value for the primary attributes of the model under investigation. With R2 values of at least 0.9422 for the learning series and 0.9271 for the assessment series, both the produced SCA - RBFNN and FFA - RBFNN correctly replicated the Sm, which indicates a considerable degree of efficacy and even a reasonable match between reported and modeled Sm. In comparison to FFA - RBFNN and ANFIS - PSO, the SCA - RBFNN is believed to be the more correct method, with the values of R2, RMSE and MAE was 0.9422, 7.2255 mm and 5.1257 mm, which is superior than ANFIS - PSO and FFA - RBFNN. The SCA - RBFNN could surpass FFA one by 25% for the learning component and 14.2% for the test data, according to the values of PI index. Ultimately, it is apparent that the RBFNN combined with SCA could score higher than the FFA and even the ANFIS - PSO, which is the proposed system in the Sm forecasting model, after assessing the reliability and considering the assumptions. [ABSTRACT FROM AUTHOR]