Capacity Of Foundations Research Articles

Impact analysis of tunnel crossing pile foundation at different angles

Shield method construction is a common method of urban subway tunnel excavation, shield tunneling through existing building pile foundation will produce disturbance to the surrounding strata, causing bending of the pile foundation, decreasing the bearing capacity of the pile foundation, underpinned piles is one of the commonly used problem-solving approaches. This paper takes the actual engineering project as the background, uses the finite element analysis software midas GTS NX to creating 3D computational models, and analyzes the effect of tunnel crossing on the surface settlement and pile foundation deformation when the shield tunnel and the axes of the underpinned beams are at different angles. The results show that: the smaller the angle is, the larger the surface settlement is, the maximum value is 2.5 mm, and when the angle is 90 degrees (vertical crossing), the settlement is the smallest, the minimum value is 2.0 mm; the effect of tunnel crossing on the vertical bending of the underpinned piles is relatively little, the effect on the horizontal displacement increases greatly with the decrease of the angle; the axial force and bending moment of the underpinned piles appear to be the maximum values at the location where the shield tunnel crosses. The above conclusions have important engineering significance for determining the optimal angle of shield tunneling through the pile foundation and realizing the minimum impact on the surrounding soil and pile foundation during the crossing.

Effects of Area Replacement Ratio and Pile Length on Composite Foundation with Biocemented Coral Sand Pile

An innovative biocemented coral sand piles (BCS-piles) composite foundations treatment technology was proposed by combining microbiologically induced calcium carbonate precipitation (MICP) technology. To investigate the bearing characteristic of BCS-pile composite foundation, a series of model tests were conducted in this study to explore the influence of area replacement rate (8.72%, 12.57%, and 19.63%) and pile length (200 mm, 300 mm, and 400 mm) on its load-settlement curve, pile axial force, pile lateral friction resistance, pile-soil stress ratio, pile-soil load sharing ratio, and particle breakage. The results show that the bearing capacity of the composite foundation increases with increasing area replacement ratio and pile length, and the settlement decreases. The bearing capacity of the composite foundation is 187.99 kPa under 60% relative compaction. With increasing area replacement ratio, the pile-body axial force, pile-side frictional resistance, and pile-soil stress ratio decreases, particle breakage increases, and the pile-soil load sharing ratio increases. In contrast, all these quantities expect particle breakage increase with increasing pile length. The bearing capacity of the foundation is related approximately linearly to the replacement plie volume per unit area, and increasing the pile length can improve the bearing capacity of the composite foundation and reduce the particle breakage more effectively. However, increasing the pile length may make construction more difficult, so comprehensive considerations are needed. From the model test results, suggested values are given for the correction coefficients in the calculation formula for the bearing capacity of the composite foundation.

The Use of Geotextiles for Controlling on The Collapse of Gypseous Soils

Gypseous soil is classified as problematic soil, characterised by its characterized by complicated and erratic behavior, and is mostly found in arid and semi-arid areas of the globe. As for Iraq. Gypseous soils cover about 30-35% of the total area of Iraq, as this type of soil is found in the Western Desert and extends to the southern parts of the country. Gypseous soils are considered strong but susceptible to sudden collapse when wet. To control the collapse of gypsum soils, Geotextiles are among the most popular kind of geosynthetic material used for soil reinforcement. The goal of this study is to determine whether woven geotextiles can improve the ultimate bearing capacity of foundations constructed on gypsum soil. The foundation is built from a strong 10mm thick steel plate measuring 100mm x 100mm. In this study, the depth of the geotextile layer that was placed at depths of (0.1B, 0.2B, 0.4B, 0.8B, B) was determined from the width of the foundation used, the number of layers of the reinforcement material (one layer, two layers, and three layers), and the layer-to-layer vertical spacing. Geotextiles: The geotextiles' breadth was also examined. The trials' findings demonstrated that adding geotextile reinforcement to soil can help it have a higher bearing capacity. and reduce the settlement of the gypsum soil. It was found that placing geotextiles at depths of (0.8B-B) is the best depth chosen, and the results were also revealed. The test showed that using three layers of geotextile gave positive results. Additionally, the test findings demonstrated that the reinforcement's composition had a significant impact on the behavior of the foundation

ANALISIS DAYA DUKUNG TIANG PANCANG STEEL PIPE PILE BERDASARKAN DATA KALENDERING DAN PDA TEST (Studi Kasus: Project Strengthening Jetty 1 & Jetty 2 PLH Existing, Desa Paring Lahung, Kec. Montallat, Kab. Barito Utara, Kalimantan Tengah)

In the field of construction, particularly in geotechnical engineering, uncertainties in foundation design approaches are frequently encountered. Geotechnical uncertainties, especially in foundation design, pose complex challenges due to the heterogeneous nature of soil and data limitations. Dynamic load testing on pile foundations is an alternative method to static load testing in geotechnical engineering for evaluating pile capacity and behavior. The results of this analysis will be compared to the design capacity of pile foundations in the breasting dolphin structure. This study on a breasting dolphin structure utilizing Steel Pipe Pile (SPP) foundations with a diameter 610 mm. PDA tests were conducted on piles at points G6-23, G7-33, G7-38, and G8-46. The study begins with a literature review to comprehend methods and theories related to pile capacity analysis based on calendaring and PDA testing. Calendaring data were analyzed using empirical methods such as the Hiley Formula to estimate the dynamic bearing capacity of each pile. The pile capacity calculated using the Hiley Formula is generally higher than the results obtained from the Case Method and CAPWAP Analysis. The relationship between pile capacity based on the Hiley Formula (calendaring) and the Case Method (PDA test) yielded a linear regression equation of y = 1.0785x - 983.07 with R² = 0.2385, indicating a weak correlation. Meanwhile, the relationship between pile capacity from the Hiley Formula (calendaring) and CAPWAP Analysis (PDA test) resulted in a linear regression equation of y = -0.006x + 2909.8 with R² = 1×10?¹, indicating almost no linear correlation between the two.

Dimensionless Machine Learning: Dimensional Analysis to Improve LSSVM and ANN models and predict bearing capacity of circular foundations

This research focuses on developing hybrid intelligence techniques to predict the bearing capacity of circular foundations using the most effective parameters. In this regard, a database involving 968 test circular foundations involving different rock properties, soil characteristics, and foundation radius has been prepared by laboratory tests for training and testing the new model presented in this study. For adequately considering various factors, the several parameters of depth (D) in m, density of soil (DS) in gr/cm3, internal angle of friction (IAF) in degree, cohesion of soil (CS) in kg/cm2, and foundation radius (FR) in m were considered as the input of the model and bearing capacity in kg/cm2 was considered as the target parameter. Three main strategies were addressed in this study. First, four well-known machine learning algorithms, Artificial Neural Network (ANN), Bagging Regressor (BR), Least Squares Support Vector Machine (LSSVM), and Gradient Boosting Regressor (GBR), were adopted to predict bearing capacity. Second, a novel and robust mathematical computation named dimensional analysis (DA) theorem was integrated with machine learning techniques to improve the accuracy and performance of the models by decreasing the number of inputs. Third, based on DA implementation, a rational mathematical formula using gene expression programming (GEP) was structured to anticipate bearing capacity. Furthermore, the sensitivity analysis process specified the impact of the five effective factors. The results of this study demonstrate the effectiveness of integrating DA with machine learning models to predict the BC of circular foundations. Among the developed models, the DA-LSSVM model showed superior performance, achieving an R² of 0.998 and 0.996 for training and testing, respectively, indicating high prediction accuracy. The results indicated that the IAF was the most sensitive factor with r = 0.709, while CS was the least sensitive with r = -0.087. A graphical user interface (GUI) app has been designed to apply the proposed models in this study conveniently. In the last step of this process, the GUI and the DA-based machine learning models were implemented by analyzing two examples. According to the findings, the GUI may be employed to make a reliable and speedy projection of the bearing capacity of circular foundations by considering a variety of input parameters.

Horizontal Cyclic Bearing Characteristics of Bucket Foundation in Sand for Offshore Wind Turbines

During the service period, the offshore wind turbine foundation mainly bears the wind load from the upper structure and the periodic loads such as wave load and sea currents from the lower structure. Long-term cyclic loads have an important impact on the cumulative deformation, foundation stiffness changes, and horizontal ultimate bearing capacity of the offshore wind turbine bucket foundation. This paper conducts cyclic loading tests on mono-bucket foundations under unidirectional and multidirectional cyclic loading conditions based on the multidirectional intelligent cyclic loading system of offshore wind turbine foundations and analyzes the cumulative effects of the loading direction, vertical load, and drainage status on the mono-bucket foundation during the cyclic loading process, effects of rotation angle, cyclic stiffness, and monotonic bearing capacity of foundation after cycles. The research results show that multidirectional cyclic loading significantly reduces the cyclic cumulative rotation angle of the mono-bucket foundation, and the maximum reduction rate can reach more than 50%. After unidirectional and multidirectional cyclic loading, the bearing capacity of the bucket foundation can be increased by up to 30% and 20%, respectively. At the same time, this paper proposes calculation formulas for vertical load, number of cyclic loading, and normalized cumulative rotation and establishes a calculation method for vertical load and bearing capacity of the foundation after cycles.

Research on the bearing performance of HSCA high-strength preloaded expansion piles in calcareous sand foundation

With the rapid development of infrastructure construction on oceanic reefs, calcareous sand, as the primary medium of these reefs, exhibits unique physical and mechanical properties such as high void ratio, low strength, and susceptibility to particle breakage. These characteristics reduce the bearing capacity and stability of pile foundations in calcareous sand foundations. This study investigates the bearing characteristics of high-strength preloaded expansion piles in calcareous sand foundations, taking into account the influence of HSCA high-performance expansion agent dosage through a series of indoor model tests and in-situ tests. The research delves into the load-settlement curves of expansion piles, the distribution of axial force and side resistance of piles, and the effects of Calcareous sand compaction and reinforcement around the piles. The results indicate that adding the HSCA high-performance expansion agent results in compaction preloading of the Calcareous sand around the pile, significantly increasing the expansion stress on the pile side, thereby enhancing the resistance on both the pile side and pile tip. When the expansion agent dosage is 20%, the ultimate bearing capacity can be increased by 56%, and the ultimate side resistance by 63%. The Coulomb strength theory of non-cohesive soil is employed to accurately calibrate the incremental side resistance of the expansion section. A prediction model for the bearing capacity of the expansion pile is established by combining the side resistance prediction model with the ultimate side resistance load-sharing ratio. The research outcomes provide important guidance for the optimization, design, and construction of high-strength preloaded expansion piles in calcareous sand foundations.

The Effect of Footing Shape on the Bearing Capacity of Shallow Foundations: A Review

The Effect of Footing Shape on the Bearing Capacity of Shallow Foundations: A Review

Equal Inputs, Unequal Outputs: How Capacity Limits Policy Implementation

As education researchers continue to investigate policies at scale and across diverse contexts, scholars must develop a better understanding of mechanisms shaping policy effects. In this study, we use the case of a federal initiative allowing high school students to use the Pell Grant for dual enrollment to investigate how institutions’ capacities shaped policy efficacy. We find that colleges’ capacities for policy implementation depended on their pre-existing resources (“foundational capacity”), the resources to execute the policy given policy-induced constraints (“execution capacity”), and the resources to provide the target population with access to the policy (“provision capacity”). We contend that institutions that may benefit the most from equitable policies also have the least capacity to implement them.

Bearing characteristics and continuous–discontinuous numerical analysis of a pressure grouting pile in a calcareous sand foundation

The complex mechanical characteristics of calcareous sand complicate comprehensive analysis of the bearing characteristics of pressure grouting piles. The bearing mechanism of pressure grouting piles is unclear. Field tests of the bearing characteristics of pressure grouting piles in calcareous sand foundations were carried out. On the basis of the field test data, the coupled finite difference method (FDM) and discrete element method (DEM) were applied to explore the settlement characteristics. The force transfer laws in calcareous sand foundations are analyzed using complex network theory. The results show that the ultimate bearing capacity of pressure grouting piles increases significantly with increasing pile diameter. An increase in the pile‒soil interface friction coefficient can increase the pile side friction resistance, which can then increase the ultimate bearing capacity of the pile foundation. The friction coefficient of calcareous sand foundations can also increase the ultimate bearing capacity of pile foundations. However, the settlement of the pile foundation also increases. The axial force of the grouting pile gradually increases as the burial depth increases. When the pile bottom is reached, the axial force of the pile body clearly increases. This study presents an effective tool for the comprehensive analysis of the bearing characteristics of pressure grouting in calcareous sand foundations.

Three-Dimensional Stratigraphic Structure and Property Collaborative Modeling in Urban Engineering Construction

In urban engineering construction, ensuring the stability and safety of subsurface geological structures is as crucial as surface planning and aesthetics. This study proposes a novel multivariate radial basis function (MRBF) interpolant for the three-dimensional (3D) modeling of engineering geological properties, constrained by the stratigraphic structural model. A key innovation is the incorporation of a well-sampled geological stratigraphical potential field (SPF) as an ancillary variable, which enhances the interpolation of geological properties in areas with sparse and uneven sampling points. The proposed MRBF method outperforms traditional interpolation techniques by showing reduced dependency on the distribution of sampling points. Furthermore, the study calculates the bearing capacity of individual pile foundations based on precise stratigraphic thicknesses, yielding more accurate results compared to conventional methods that average these values across the entire site. Additionally, the integration of 3D geological models with urban planning facilitates the development of comprehensive urban digital twins, optimizing resource management, improving decision-making processes, and contributing to the realization of smart cities through more efficient data-driven urban management strategies.

Corrosion Mechanisms, Responses, and Mitigation Strategies for Steel Piles in Offshore Wind Turbines: A Comprehensive Review

ABSTRACTWind energy offers significant advantages over fossil fuels, including extensive energy storage and environmental sustainability. Offshore wind turbines serve as the primary technology for harnessing offshore wind power. However, the corrosive effects of the marine environment pose serious threats to their safety and stability. This paper provides a comprehensive overview of corrosion issues affecting steel pipe pile infrastructure, focusing on the following key aspects: (1) Differentiating corrosion mechanisms under various environmental conditions, (2) analyzing the comprehensive corrosion response, particularly the changes in mechanical properties of the pile–soil interface and the bearing capacity of steel pile foundations, (3) summarizing the patterns and trends in corrosion processes to offer theoretical insights for engineering design, and (4) reviewing commonly employed corrosion prevention methods and their respective applicability in relation to specific corrosion mechanisms and responses.

A Geotechnical Centrifuge Study on the Bearing Capacity of Ring Foundations Reinforced by Stone Columns

A Geotechnical Centrifuge Study on the Bearing Capacity of Ring Foundations Reinforced by Stone Columns

Seismic Bearing Capacity of Strip Foundations Placed on Stable Slopes of Homogeneously Fractured Rock Mass

Seismic Bearing Capacity of Strip Foundations Placed on Stable Slopes of Homogeneously Fractured Rock Mass

Insights on cyclic cone penetration in sand from centrifuge and numerical modelling

The cone penetration test (CPT) is widely used to determine soil stratigraphy and soil characteristics. Moreover, correlations derived from CPT measurements are used increasingly in geotechnical design, for instance, to estimate the bearing capacity of foundations and soil liquefaction susceptibility. Correlations based on the results of cyclic CPTs may also be useful in predicting cyclic events such as vibro-driving of open-ended piles or suction bucket installation using pressure cycling. This is because the wall thickness of open-ended piles or suction buckets is similar to the cone diameter, such that similar mechanisms are likely to apply. Consequently, this study focuses on the mechanisms that occur during cyclic cone penetration in sand using a combination of centrifuge and numerical modelling. The results of this study highlight the importance of cyclic displacement amplitudes, gap formation below the tip, advancement per cycle, and soil state change on the cone resistance.

Расчет оснований массивных подпорных стен с применением электронных таблиц

The paper deals with the calculation of the foundations of massive retaining walls. The authors show the design features of various types of retaining structures. The paper analyses the existing theoretical and practical methods for calculating the bearing capacity of foundations. The paper provides updated computational formulae for calculating loads and pressures on retaining structures. The paper describes an engineering method for calculating the active pressure on retaining structures. The paper presents algorithms of computational operations for calculating foundations for the first and the second groups of limit states in a spreadsheet. The authors describe the details of the computational iterative process of tabular data of the load-bearing capacity coefficients for the soil foundation. The paper shows the results of spreadsheet application to the calculation of retaining wall foundations. The authors draw conclusions on the conducted study of spreadsheet application in calculations of solid retaining wall foundations.

Design Scenarios for The Foundation of 85 m Height 400 Tons 2MW Wind Power Plant Aqmola Region

The problems in the design of foundations of wind power plants are presented. The purpose of the article is to develop experimental and theoretical recommendations for the calculation and design of foundations of wind power plants. A complex of theoretical, analytical, and numerical modeling of the foundations were used: analysis of natural-climatic and socio-economic zones of Aqmola region; collection of loads on the foundation of wind power plants using SCAD software and estimation of bearing capacity of foundation and soil-base. In total 3 design scenarios were adopted: slab, driven pile and bored pile foundations. The results revealed that the highest bearing capacity is in bored pile foundation with the value of 570 kN (960 kPa working load capacity), which is slab (580 kPa) and driven (470 kN, 770 kPa working load capacity) pile foundation. In terms of materials resources the most efficient appeared to be the scenario of driven pile foundation.

Semi‐Analytical Study of Pile–Soil Interaction on a Permeable Pipe Pile Subjected to Rheological Consolidation of Clayey Soils

ABSTRACTPermeable pipe pile, a novel pile foundation integrating drainage and bearing functions, improves the bearing capacity of the pile foundation by accelerating the consolidation of the soil around the pile. In this study, a mathematical model is established to simulate the consolidation of surrounding clayey soils and the pile–soil interaction, where the rheological properties of the soils are described with the fractional derivative‐based Merchant model, and the impeded drainage boundary is used to simulate the pile–soil interfacial drainage boundary. Corresponding solutions for pile–soil relative displacement, skin friction, and axial force on the pile shaft are derived by means of semi‐analytical methods, and they are validated by comparing with experimental results and numerical simulation results. Based on the proposed semi‐analytical model, a series of parametric analyses are conducted to investigate the influences of fractional orders, viscosity coefficients, pile–soil interface parameters, and pile‐head loads on the pile–soil interaction characteristics. It is observed that during the transition stage, the axial force increases linearly with depth in the plastic segment, and then increases nonlinearly in the elastic segment until it decreases after reaching the neutral plane. In the elastic segment, the axial force on the pile shaft for a given time increases with the increases in the fractional order or the pile–soil interface parameter, but decreases with the increase of viscosity coefficient.

A FEM‐DEM Coupling Analysis on Bearing Capacity of Sandy Soil Foundation Considering Fabric Anisotropy

ABSTRACTWith the acceleration of urbanization, the stability of the foundation is being more crucial to the performance and service of the superstructure. As our understanding of the factors influencing soil's physical and mechanical behavior deepens, it becomes increasingly challenging for traditional limit equilibrium and limit analysis methods to accurately consider the complex factors affecting foundation stability, such as initial fabric anisotropy caused by the particle morphology and geological deposition in sand. Although some scholars had used advanced constitutive models in the finite element method (FEM) to investigate the influence of initial fabric anisotropy on mechanical responses of foundations, this approach failed to reveal the microscopic information underlying the shear failure of sandy soil foundations. In this study, the influence of the initial fabric anisotropy of sandy soil on the ultimate bearing capacity and shear failure mode of shallow foundation is studied using the hierarchical FEM and discrete element method (DEM) coupling analysis method. Four representative volume elements (RVEs) with varying initial bedding plane angles are constructed in DEM for characterizing different initial fabric anisotropies, and the specific stress–strain information of DEM RVEs is directly passed into the corresponding Gauss points in FEM to replace the conventional constitutive model. Numerical results show that the initial fabric anisotropy affects the ultimate bearing capacity and shear failure mode of shallow foundations significantly, and the corresponding micromechanical behaviors at different local Gauss points have been explored, which advances our understanding of the micromechanisms underlying the progressive shear failure of sandy soil foundations significantly.

Laboratory experimental study on GESC combined with electroosmosis for ground improvement

To verify the effect of electrokinetic geosynthetics-encased stone columns combined with electroosmosis on soft soil foundation reinforcement, laboratory model experiments were conducted using stone columns (SC), geosynthetics-encased stone columns (GESC) with/without electroosmosis. The energy consumption coefficient and drainage rate of electroosmosis, the shear strength and water content distribution of soil, and deformation law of the pile section after static load tests at different depths were studied. Experimental results show the strength of soil around the pile increases after electroosmosis, enabling better support for the pile body, while the pile-soil stress ratio of the gravel pile is reduced and the side friction resistance is effectively exerted. Moreover, the expansion deformation distribution of the gravel pile in both the E-GESC and GESC configurations is basically the same, and the maximum radial deformation is less than that observed in the SC. Most of the deformation occurs within a range of 2 times the pile diameter below the boundary line of the wrapped section. The ultimate bearing capacity of the composite foundation formed by the electroosmosis with geosynthetics encased stone columns (E-GESC) method is 6.6 times that of the SC and 3.8 times that of the GESC, demonstrating a significantly enhanced reinforcement effect.