Lateral Pile Capacity Research Articles

An Analysis of the Flexural Stiffness and Horizontal Bearing Capacity of CFRP Composite Pipe Piles in Marine Environments

Carbon-fiber-reinforced polymer (CFRP) is a composite material consisting of a resin matrix reinforced with carbon fibers. This study focuses on CFRP composite pipe piles as the subject of investigation, exploring the impact of substituting steel bars with CFRP bars on the bending performance of pipe piles through rigorous three-point bending tests. The attenuation of flexural stiffness in CFRP pipe piles under a chloride salt environment was anticipated. The lateral bearing capacity of CFRP pipe piles was calculated by introducing a stiffness degradation coefficient for the piles and utilizing the finite difference method. The findings of the analysis suggest that as the CFRP reinforcement replacement rate increases, the initial bending stiffness of the composite pipe pile experiences a corresponding decrease. After serving for 28.15 years, the steel reinforcement within the pipe pile commences rusting, resulting in a nonlinear decline in the bending stiffness of the composite pipe pile. As the service time of pipe piles increases, a higher replacement rate of CFRP reinforcement results in a slower attenuation of pile stiffness. Consequently, both the horizontal displacement at the top of the pile and the bending moment along the body of the composite pipe pile gradually increase over time. During the same service period, the higher the rate of CFRP reinforcement, the less noticeable the attenuation in the horizontal bearing capacity of the pile shaft.

Lateral capacity of group helical piles in sand: an experimental and numerical study for sustainable infrastructures

ABSTRACT Helical piles are integral to support resilient infrastructures subjected to axial and lateral loads. This study explored model-scale testing of group helical piles in cohesionless soil in a rigid box. Initially, a total load of 5000 N is applied to the pile raft model, followed by a lateral load of 1600 N. Nine model tests are performed with a configuration of four, six, and nine, having conventional, single helical, and double helical piles. The data logger facilitated data collection using MATLAB software, and the load was increased at rate of approximately 4.9N/sec. The computed average reduction in the displacement of Single and Double Helical Pile Rafts is observed as 36.43% and 55.71%, respectively, compared to Conventional Pile Rafts. The addition of a second helix further reduced lateral displacement by 19.27%. Numerical analysis on Plaxis-3d showed that the experimental and numerical results are in good agreement.

Probabilistic ultimate lateral capacity of two-pile groups in spatially random clay

ABSTRACT The undrained lateral capacity of a group of two side-by-side piles has been studied in uniform clay, but the effect of spatial variability in clay strength on lateral pile capacity remains unclear. This paper describes probabilistic ultimate lateral capacity for two circular piles in spatially variable undrained clay. An adaptive finite element limit analysis based on random field generation combined with Monte Carlo simulations is applied. The lateral capacity statistics of two-pile groups with different combinations of pile spacings and pile roughness are presented. It is found that the consideration of the random nature of clay strength leads to a significant decrease in the lateral pile capacity, especially at a pile spacing approximately equal to the pile diameter. The factor of safety required to attain a target probability of failure is provided as a function of pile spacing. The obtained results give guidance for the reliability-based design of laterally-loaded two-pile groups in spatially varied clay and can also be applicable for understanding the lateral translation of two interfering cables and pipelines deeply buried in random clay.

Study of The Axial and Lateral Bearing Capacity of Bored Piles Affected by Liquefaction

Abstract Liquefaction can lead to structural failure as it reduces the bearing capacity of building foundations. This phenomenon occurs in saturated sandy soils where pore water pressure increases, significantly decreasing effective soil stress. Evaluating the axial and lateral bearing capacity of bored piles affected by liquefaction is crucial to ensure the stability and performance of foundation systems. This study focuses on assessing the capabilities of bored piles in the Governor’s Office of Sulawesi Barat Province, which are influenced by liquefaction phenomena. The empirical approach applied the O’Neill and Reese 1989 method, while the numerical approach used RS Pile. The calculation results revealed decreased axial bearing capacity under liquefaction conditions. In non-liquefaction, PC.4 can withstand up to 24946 kN, with displacements of 0.94 cm (x), 0.39 cm (y), and 1.12 cm in settlement. In liquefaction, it decreases to 2876.78 kN, with displacements of 1.32 cm (x), 0.86 cm (y), and 1.68 cm in settlement. In non-liquefaction, PC.3 can withstand up to 17407.93 kN with displacements of 0.02 cm (x), 0.04 cm (y), and 0.06 cm in settlement. In liquefaction, it decreases to 1713.05 kN, with displacements of 0.02 cm (x), 0.05 cm (y), and 0.07 cm in settlement.

Static lateral pile analysis of Dubai sedimentary rock in UAE

Analysis and calculation of lateral pile load capacities using appropriate methods is a challenging task for geotechnical engineers. Primarily, piles in Dubai, UAE, are rock fully socketed with top strata of medium dense to dense silty sand or sedimentary rock resisting lateral loads. In this study, the results of two field pile lateral load tests were chosen for examining different methods used by local geotechnical engineers, where ground lithology constitutes fragile sandstone up to ∼8 m below ground level overlying extremely weak conglomerate/siltstone. Assessing the efficacy of design parameters and analysis methodology is a pivotal aspect in preliminary evaluation of the lateral load capacity of piles. In this research, two commonly adopted approaches (non-linear p–y analysis using the LPile software and finite-element analysis using the Plaxis 3D software) were assessed by comparing them with field test results to predict the lateral load capacity precisely. Design parameters were based on borehole data and laboratory tests near the test location. Even though finite-element analysis predicted better than non-linear p–y analysis, lateral load capacities were underestimated in both piles analysed, which was related to assessment of input parameters. In addition, finite-element analysis was used to back-calculate the elastic modulus of rock that yields lateral deflections of piles close to field test results.

Analysis Study of Lateral Bearing Capacity and Deformation of Square and Circular Concrete Piles as an Alternative Structure for Infrastructure Projects

Piles are one type of foundation that used to transmit the load acting on a structure to the ground below. The required embedment length value depends on the load acting on the superstructure, pile specifications, and soil type. This study was conducted to analyze the lateral bearing capacity and lateral deformation that occurred on square and circular piles with sizes of 30 cm, 35 cm, 40 cm, 45 cm and 50 cm with embedment lengths from 1 meter to 15 meters. The type of soil under review is cohesive soil. The calculation method used is the Broms’ Method and computer software. The results of the analysis show that the lateral bearing capacity of square piles is greater than that of circular piles. The change in L/d ratio does not affect the magnitude of the lateral bearing capacity of rectangular and circular long piles. The resulting lateral deflection value also does not exceed the allowable limit (2.54 cm).

Numerical study on lateral response of piles in sandy slopes employing a hardening soil model

The present study investigates the lateral response of piles on sandy slopes. PLAXIS 3D has been employed to perform three-dimensional finite element analysis. A number of numerical assessments have been conducted on the pile with a constant slope height, having different ground slope inclinations from 10° to 30° in sandy soil with different relative densities from 30% to 70%. The embedment length-to-diameter ratio is 30. Responses are compared with the results of horizontal ground conditions. The impact of pile position on the sloping ground has also been investigated by placing the pile at various positions from crest to toe of the sloping ground. The analysis has been done by providing the pile with lateral displacement in one case and a lateral load in the other. The current investigation will examine slope stability with and without pile reinforcement. Lateral pile capacity increases as relative density increases and it decreases as the slope of the ground increases. Maximum lateral displacement and maximum bending moment decrease as relative density increases and increase when the level ground is changed to sloping ground. The depth of the maximum bending moment is also reported.

Deriving a p-y curve from lateral pile load tests – Case studies in alluvial OC clays

Estimating lateral pile capacity is one of the most typical works for geotechnical engineers. Although it has been a routine calculation, obtaining reliable results is still challenging, especially when the ground condition is unfamiliar. Fortunately, the lateral pile capacity prediction can be performed by deriving a p-y curve from the load-deformation curve measured during pile testing. In cases where a preliminary test pile exists, fortunately, the p-y curve can be generated easily using a subgrade reaction approach suggested by Davisson and Gill (1963). Two lateral pile load test results were used to show the prospect of this method for practical applications. The field tests were on driven and bored piles with different diameters and lengths embedded in alluvial OC clays at two different sites in Jakarta, Indonesia, where both piles were categorised as long piles. Derivation of p-y curves was performed with a simple spreadsheet. Then, the obtained p-y response was used to estimate the load-deformation curve. Results showed that the back-calculated curve agree well with the measured data. This outcome might be because the p-y curves were directly derived from the field test where the pile experienced in-situ stress, resulting in a more representative of the actual condition.

P-y Curve for Estimation Lateral Bearing Capacity of Single Bored Pile in Overconsolidated Soils Using The Three-Dimensional Finite Element Method.

The p-y curve method is widely used to predict piles’ lateral bearing capacity. It assumes independent springs with a non-linear modulus of subgrade reaction for analyzing soil resistance (p) and deflection (y). This study determined the lateral bearing capacity using the three-dimensional finite element method (FEM-3D) and finite difference method (FDM), which was later compared with the loading test results. Therefore, the pile head condition is assumed to be the free-head. To determine the lateral bearing capacity, input the lateral deflection at the pile head. In FEM-3D, the pile and lateral deflection in the pile head is modeled using cluster elements and surface-prescribed horizontal displacements, respectively. On the other hand, in FDM, pile heads and boundary conditions are modeled using displacement and moment. The results of the lateral bearing capacity using FEM-3D provide predictions that are close to the loading test, with a difference of about 4.2%. In contrast, the FDM method produced conservative results due to its reliance on semi-empirical formulas. The ultimate soil resistance (Pult) formula in FDM is more suitable for rigid-pile behavior. The prediction of lateral bearing capacity using FEM-3D provides more accurate results due to its ability to model complex soil-pile interaction. The stress history, soil-pile interaction, and more reliable constitutive models can be modeled in FEM-3D.

Corrosion initiation life and lateral bearing capacity of RC square piles considering different corrosion zones

This paper analyzes the differences in the corrosion initiation life and lateral bearing capacity of reinforced concrete (RC) square piles in different marine corrosion zones. A chloride diffusion model is presented by considering the effect of environmental factors on the chloride apparent diffusion coefficient. Different surface chloride concentration models in different corrosion zones are used to predict the corrosion initiation life of RC square piles. The time-dependent degradation law of bending stiffness of RC square piles in different marine corrosion zones is investigated. The lateral bearing capacity of RC square piles with different bending stiffness reductions in different corrosion zones is analyzed. The analysis results show that the corrosion initiation life of RC square piles decreases sequentially in the atmospheric zone, submerged zone, and tidal and splash zones. At the same exposure time, the stiffness reduction coefficient in the tidal and splash zones is the smallest, compared with atmospheric zone and submerged zone. The maximum lateral displacement, bending moment and negative shear force of RC square piles with variable stiffness are greater than those of invariable stiffness piles in different corrosion zones.

Implementing the slice method to evaluate lateral pile capacity in cohesive soil

AbstractThis paper presents a novel method for evaluating the resistance factor used for the estimation of lateral pile capacity in cohesive soil. The developed method uses limit equilibrium and mobilized strength principles, which are implemented on the half‐symmetric problem using a modification of the traditional slice method. The soil medium is discretized into a polar numerical grid, allowing sliplines investigation independently of geometrical shape assumptions. The paper presents the development of the SLIP (Snake Locomotion Iterative Procedure) optimization method, which enables an effective and efficient search of the critical slipline out of all slipline geometries that can be generated within the numerical grid. The SLIP iteratively updates the evaluated optimal slipline, according to the criterion of minimizing the pile resistance factor, N. The obtained solutions are consistent with previous plasticity results, with special attention to the smooth pile solution which is bounded between the best lower‐ and upper‐bounds solutions to date. The work utilizes safety map principles to prove the uniqueness of the solution.

Time dependent analysis of lateral bearing capacity of reinforced concrete piles combined with corrosion and scour

This study investigates the effect of chlorine corrosion and flow scour on the lateral bearing capacity of piles. A chloride diffusion model was established to obtain the initial corrosion time of reinforcement based on Fick's second law. The degradation of stiffness after corrosion is represented by a reduction coefficient. The finite difference method is used to solve the deflection differential equation of laterally loaded piles. The maximum scouring depth of piles in cohesive soil and the variation of scouring depth with time are calculated by empirical model. The calculated results from the analytical solution revealed that the pile stiffness decreases with the exposure time. As the time increase, the lateral displacement and shear force decrease on the other hand the bending moment increases. The increase of flow velocity and pile diameter results in the increase of the maximum scour depth around the pile. The bending moment, shear force, and lateral displacement of piles after scour increase significantly compared to the lateral bearing performance of piles before scour.

Effect of pile spacing in helical pile groups in soft clays under combined loading

Helical piles have lately emerged as a viable alternative foundation solution in offshore geotechnical applications. The helical piles are typically installed in groups to resist large loads from the structures and may encounter combined loading due to some factor such as the waves from the water surrounding it. Recent research works on group helical piles focused mostly on piles embedded in sand and their response to individual loading regimes. This research has been carried out to examine the behaviour of the helical pile groups embedded in soft clay subjected to combined uplift and lateral loading considering three different configurations (rectangular, triangular, and square) and different spacings between the helical piles (2 to 5 times the helix diameter). A three-dimensional finite element model is developed to predict the load-displacement response of the group and is validated against the 1 g laboratory scale model test results. The findings from the analyses reveal that the influence of combined loading reduces the lateral capacity of the group helical pile. The spacing between the helical piles also has a substantial impact on the response to combined loading. The role of critical spacing ratio for various configurations has also been discussed in this paper.

Experimental study on monotonic and cyclic lateral behavior enhancing mechanism of semi-rigid pile under different foundation reinforced methods in clay

Monopiles are the most commonly utilized foundation type for offshore wind turbines. Due to continuous growth in the capacity of offshore structures, increasing the diameter of piles is a relatively simple but costly method. How to improve the bearing capacity of monopile foundations without increasing the pile diameter is the research purpose of this paper. A series of laboratory model tests of laterally loaded monopiles in clay were carried out considering different foundation reinforcement methods (i.e., annular point post-grouting, distributed post-grouting and jet-grouting) to investigate the lateral monotonic and cyclic response of unreinforced and reinforced piles. As a result, the three foundation reinforcement methods improve the lateral capacity of piles, among which jet-grouting-reinforced piles have the greatest improvement. After the monotonic test is completed, an excavation test is carried out. It is determined that the cement slurry injected by the annular point post-grouting reinforcement mainly diffuses in the clay by splitting, while the reinforcement body formed by the distributed post-grouting and jet-grouting more evenly covers the outer surface of the pile, and the effect of improving the lateral capacity is improved. The accumulated displacement calculation formulas of different reinforced piles are obtained. The accumulation coefficient of distributed post-grouting and jet-grouting reinforced piles is small, which means that they can more effectively reduce the cumulative displacement of the pile.

Influence on the lateral response of offshore pile foundations of an asymmetric heart-shaped scour hole

The presence of local scour seriously jeopardizes the safe operation of offshore wind power systems, as local scour leads to the formation of scour holes, which will decrease the bearing capacity of the foundations of these structures. Due to the directionality of waves and currents, scour holes typically have an asymmetric plane shape that creates unequal soil pressure on each side of the pile, and this pressure difference will have a more unfavorable impact on the pile lateral response than that of a scour hole with a symmetric geometry. In this study, an asymmetric heart-shaped scour hole is defined, and parametric analyses are performed to determine the pile lateral response using a three-dimensional (3D) finite element (FE) method in which the scour hole dimensions and the loading directions were varied. As the scour depth increased from 1.0D to 5.0D, the difference in the reduction ratio between the pile lateral capacities for the two scour hole shapes increased from 0.2% to 7.0%, while the gap in the pile bending moments decreased. Moreover, the results indicated that a heart-shaped scour hole was not sensitive to changes in the side slope angle. The pile lateral capacity was found to be lowest when the lateral load was applied negatively along the y axis; the gap in the pile maximum bending moments for the three loading directions was 90 kN·m, and the gap reduced as the scour depth increased.

An existing pile efficiency method for the design of lateral new pile behavior in sites with existing piles

Foundation reuse is the development trend of sustainable engineering construction. However, the reuse of existing piles as rigid inclusions and their contribution to newly constructed piles (new piles) under different new and existing pile spacings are still insufficiently understood. In this paper, a series of numerical investigations were conducted based on centrifuge tests to examine the effect of existing piles on the lateral behavior of new piles under different pile spacings. The existing pile efficiency that reflects the contribution of existing piles to the lateral capacity of new piles was analyzed, and it was shown that the impact of existing piles decays exponentially with the pile spacing between new and existing piles. Beyond the spacing of 6 D ( D: the diameter of new piles), the lateral new pile–soil–existing pile interaction can be neglected. A parametric study was subsequently performed to quantify the existing pile efficiency under different variables, including the new pile-head restraint, loading displacement, bending stiffness, load eccentricity, embedded depth, and soil properties. Finally, an existing pile efficiency-based method for the estimation of the lateral capacity of new piles was proposed, which provides an efficient way to design laterally loaded new piles in sites with existing piles.

An extension of Broms’ theory to unsaturated soils

This paper presents an analytical method to predict the horizontal capacity of piles in unsaturated soils. The method extends the well-known Broms approach to account for the combined effect of the groundwater table and the apparent cohesion of the unsaturated soil above it. Similar to the original formulation of Broms, the present method calculates the maximum horizontal force and bending moment that can be sustained by the pile for two different head fixities (i.e. free-head and restrained-head) as a function of non-dimensional parameters that depend on the geometry and flexural resistance of the pile (i.e. yielding moment), the soil resistance and the type of failure mechanism (i.e. short, intermediate or long pile). Compared to Broms’ solution, the method introduces additional non-dimensional parameters that relate the water retention behaviour of the soil to the geometry of the pile. The proposed formulation accurately predicts the lateral capacity of piles as experimentally measured in previous works. Results confirm that consideration of the partially saturated state of the soil above the groundwater table is essential for a reliable estimate of the horizontal capacity of piles.

Assessment of Lateral Load Capacity of Single Pile at Bettiah Site: A Parametric Study

Pile foundations are widely used and accepted approach to transfer superstructure load to a deeper and stronger stratum. This work has been focused on the assessment of the effect of different parameters associated with piles such as pile diameter, pile length, grade of concrete and pile head condition (i.e., free or fixed) on the lateral load capacity. To evaluate the lateral load capacity considering the aforementioned parameters ‘IS Code’ and ‘Matlock and Reese’ methodologies have been utilized. The soil exploration data has been collected from ten different boreholes near to the railway bridge at Bettiah site, Bihar. The results of lateral pile load at different boreholes reflects that the lateral load capacity of pile significantly increased with the increase of pile diameters and grades of concrete. The lateral load capacity of pile was increased approximately by 13%, from both IS Code and Matlock and Reese methods, when the grade of concrete was increased from M25 to M40. It was also found that the condition of pile head also plays a major role in lateral load capacity. The lateral load capacity of pile obtained from IS code method under fixed head condition was found to be higher as compared to free head condition. It has also been observed that the lower values of ultimate lateral load capacity for fixed head and lower values for free head condition was obtained by IS Code as compared to Matlock and Reese method.

Prediction of Undrained Lateral Capacity of Free-Head Rectangular Pile in Clay Using Finite Element Limit Analysis and Artificial Neural Network

Prediction of Undrained Lateral Capacity of Free-Head Rectangular Pile in Clay Using Finite Element Limit Analysis and Artificial Neural Network

Impact of Suction on the Near Surface Lateral Soil Response using Centrifuge Modeling

Recent studies have shown that unsaturated soils lead to greater lateral pile capacity. This study aims to experimentally assess how suction stress affects the lateral response of piles in unsaturated cohesionless soil. Two centrifuge tests were performed at 50 g to evaluate the effect of suction stress in the soil. Lateral loads were applied monotonically on a single free-head pile in a displacement-controlledmanner to a maximum pile head displacement of 0.44 m. The first test was conducted on fully saturated cohesionless soil, while the second test was performed in an unsaturated state with a mixed unsaturatedsaturated soil layer. The water table was lowered to about 0.12 times the embedded pile depth to ensure an unsaturated condition in the zone closer to the surface of the soil. Lateral response assessment indicates that the unsaturated soil influenced the pile head response, leading to larger applied lateral loads for similar pile displacements in comparison to the fully saturated soil test. Experimental findings reveal that suction stress played a meaningful role in magnitudes of pile bending moments and lateral resistances for unsaturated cohesionless soils.