Lateral Pile Capacity Research Articles

An analytical method to evaluate the capacity of laterally loaded piles in unsaturated soils

The growing pressures of climate change, increased usage and unprecedented geo-hazards impose a modification in the way civil engineering structures are designed and constructed. This isparticularly true for geotechnical works, which are very sensitive to changes of environmental conditions. For instance, the response of a pile under lateral loading is strongly influenced by the stiffness and strength of the first few metres of soil below the surface, which are often partly saturated. To consider this effect, the present paper describes an analytical method, which extends the well-known Broms approach to predict thelateral capacity of piles in unsaturated soils. More specifically, the proposed method considers the combined effects of the position of the ground water table and the extra strength of the partially saturated soil above it. Compared to Broms approach, the solution introduces four additional non-dimensional parameters that relate the soil-water retention behaviour to the geometry of the pile. The method provides a direct evaluation of the lateral pile capacity in partly saturated soils, which can be used as a basis for more accurate design.

Analysis and intrinsic correlations of partially head-restrained piles under lateral loading: virgin sites and new-existing pile sites

Piles are commonly used under partial head-restraint conditions. Currently, quantification of the lateral capacity of partially head-restrained piles is an open problem. This paper reports the results of a comparative study on the partially head-restrained behaviours of single piles in virgin sites and new piles in sites with existing piles. The lateral performance of new piles affected by pile-head restraints was examined and compared with that of single piles in virgin sites, and the characteristics of new and single pile capacities with respect to pile-head restraints were evaluated. An intrinsic H–δδ correlation (the lateral pile capacity and the factor linking partially head-restrained piles to pure free- and fixed-head piles) is discussed, which enables the calculation of capacities of partially head-restrained piles based on those of pure free- and fixed-head piles. In addition, analytical models of the δδ–λ correlation (λ represents the pile-head restraint percentage) are deduced. By combining the δδ–λ and H–δδ correlations, the lateral pile capacities for arbitrary pile-head restraints in virgin sites and sites with existing piles are calculated. The proposed method is comprehensively validated by numerical and literature examples, showing significant advantages in the determination of the lateral pile capacity considering head restraints.

Effect of Contact Pressure on the Lateral Capacity of Piles

This study aims to determine how to contact pressure affects pile capacity. First, a single pile model was subjected to a total of six tests, five conducted under varying surface loads and one conducted on a single pile raft. Plaxis- 3D was utilized in the second step of numerical modelling to imitate experimental activity. The galvanized iron pipe was used as a model pipe, and for confining pressure, a rectangular plate made of aluminum had a slot in the center for placing a pile. For numerical study in Plaxis 3-D pile was used as a model pile surrounding the soil to find the relative displacement between the piles and surrounding the soil. In the proposed research work, the axial and lateral capacity of the pile increases due to the contact pressure of the soil. As a result of the interaction between the pile and the raft, when the results were compared, the pile tightly connected to the raft took less axial force than the other pile that was not. Similar outcomes emerged from the trials when they were conducted in Plaxis 3-D.

Empirical and numerical study of the static lateral response of socketed pile in Dubai, UAE

In geotechnical engineering practice, it is often a challenging task to select a suitable method for the calculation of the lateral load capacity of piles. In Dubai, UAE piles are predominantly rock socketed with top layers commonly medium dense to dense sand or Dubai sedimentary rock contributing to bearing lateral loads. In the present study, the results of two lateral load field tests on piles were selected and used for evaluating various methods adopted by local geotechnical engineers for evaluating lateral load capacity. For the selected piles, the top layers of the ground lithology consist of medium dense to dense sand, which is critical in the evaluation of the lateral capacity of piles. Generally, either the Broms method or p–y non-linear analysis is adopted by local geoengineers for lateral load analysis of piles due to the simple input requirements and quick calculations. With advancement in computing capabilities, geotechnical engineers also adopt numerical analyses. As part of this study, various methods adopted were evaluated in terms of their advantages, limitations and accuracy in predicting the lateral load behaviour of piles. Commonly adopted methodologies such as the Broms method were found to have limitations that underestimate pile capacities, resulting in overdesign of pile sizes leading to higher costs, whereas, comparatively, numerical approaches predict more accurately the lateral load behaviour of piles.

Lateral Load Capacity and p-Multiplier of Group Piles with Asymmetrical Pile Cap under Seismic Load

Earthquakes are a high-risk natural phenomenon in Indonesia, which is between three tectonic plates: the Eurasian, Pacific, and Indo–Australian plates. This study examines the response of bored piles with asymmetrical pile cap in the Auditorium Building of Brawijaya University to seismic loads, which is still rare to conduct this research. This study assessed based on 3D finite element-numerical approach, where lateral resistance and p-multiplier values compared on the effects of combination lateral loads, pile stiffness, and soil stiffness. The behavior of lateral resistance and deflection group piles with asymmetrical pile cap and single pile with square pile cap gives a good agreement. The side slope of the pile cap can increase the shear zone, increase the lateral resistance, and the most considerable lateral resistance to the lowest occurs in the horizontal direction, opposite the loading direction. In addition, the pile configuration that is not symmetrical gives an increasing p-multiplier value followed by an increasing deflection and the p-multiplier from the 3D finite element method was within the recommended range.

An Experimental and Theoretical Studies Wings Piles at Different Sandy Soil Densities

Increasing the cross-sectional area of the piles or adding wings to the piles are two strategies for increasing the bearing capacity of the piles to resist lateral stresses. Small and full-scale finite element models were used to investigate the effect of adding the wings on the laterally loaded pile bearing capacity in this study. Four embedded ratios (4, 6, 8, and 10) were used with various wing dimensions and numbers. The results showed that adding wings to the pile increases the resistance to lateral loads and reduces the lateral displacement significantly. +To achieve the highest lateral resistance, the wings should be fixed parallel to the lateral load applied to the pile and close to the pile head. The ultimate lateral applied load is proportional to the rise in relative density. The lateral pile capacity was increased by 16.5%, 18.4%, and 33% in dense, medium, and loose sand, respectively, at the same length to diameter ratio (L/D). Increasing wing length improves lateral capacity significantly. At a failure, the lateral pile capacity was 18% and 8.5 % for Lw, equal to 112 mm and 56 mm, respectively. Another study's purpose was to determine how increasing the number of wings affected pile resistance. The lateral pile capacity at failure was increased by 9.8 % for two wings, 18.4 % for three wings, and 18 % for four wings.

Numerical modeling of single closed and open-ended pipe pile embedded in dry soil layers under coupled static and dynamic loadings

Abstract For the design of a deep foundation, piles are presumed to transfer the axial and lateral loads into the ground. However, the effects of the combined loads are generally ignored in engineering practice since there are uncertainties to the precise definition of soil–pile interactions. Hence, for technical discussions of the soil–pile interactions due to dynamic loads, a three-dimensional finite element model was developed to evaluate the soil pile performance based on the 1 g shaking table test. The static loads consisted of 50% of the allowable vertical pile capacity and 50% of the allowable lateral pile capacity. The dynamic loads were taken from the recorded data of the Kobe earthquake. The current numerical model takes into account the material non-linearity and the non-linearity of pile-to-surrounded soil contact surfaces. A lateral ground acceleration was adapted to simulate the seismic effects. This research emphasizes modeling the 1 g model by adapting MIDAS GTS NX software. This will, in turn, present the main findings from a single pile model under a combined static and dynamic load. Consequently, the main results were first validated and then used for further deep investigations. The numerical results predicted a slightly higher displacement in the horizontal and vertical directions than the 1 g shaking table. The shear stress–shear strain relationship was predicted. Positive frictional resistance for the closed-ended pile was captured during the first 5 s when low values of acceleration were applied and, consequently, the pile resistance decreased and became negative. Internal and external frictional resistance was captured for the open-ended pipe pile. Overall, frictional resistance values were decreased with time until they reached the last time step with a minimum value. As a result, the evaluation of the current study can be used as a guide for analysis and preliminary design in engineering practice.

A Simplified Analytical Method of Lateral Bearing Capacity of Rigid Single Pile Considering All Soil Reactions in Sand

A Simplified Analytical Method of Lateral Bearing Capacity of Rigid Single Pile Considering All Soil Reactions in Sand

A Numerical Investigation of Laterally Loaded Steel Fin Pile Foundation in Sand

Pile foundations are often subjected to lateral loadings. By adding steel plates (fins) to the side of the pile, steel fin pile foundations (SFPFs) can improve the lateral load capacity of piles. Existing numerical studies using elastic–perfectly plastic models (e.g., Mohr–Coulomb model) for soil behavior may result in unrealistic load response when modeling soil–pile interaction in dense sand due to the lack of consideration of strain-hardening/softening behavior. In the present study, finite-element analyses were conducted to understand the effect of fin geometry on the lateral load capacity of SFPFs. The prepeak hardening and postpeak softening soil behavior was accounted for by varying soil strength parameters with plastic shear strain based on a modified Mohr–Coulomb model. The developed model was calibrated and validated against well-documented experimental and field tests in the literature. The validated model was subsequently used to conduct a parametric study to understand the effect of fin geometry on the response of SFPFs subjected to lateral loading at the pile head. The behavior of SFPFs at different displacement levels and load levels was studied. The effect of the relative density of soil on the performance of SFPFs was also investigated. Based on the numerical simulation results, the optimal fin width and length values for mobilizing soil resistance were suggested and the underlining mechanisms affecting the efficiency of fins were discussed.

Experimental study on evaluating the lateral load capacity of raker pile in sloping ground

ABSTRACT A lot of uncertainty is associated with the behavior of pile foundations on the sloping ground due to factors like soil – pile interface and vague evaluation of pile bearing capacity. These constraints have a considerable impact on the extensive implementation of deep foundation on sloping ground. Comprehensive research studies were carried out on laterally loaded vertical piles on horizontal ground whereas only a limited number of studies have been conducted on the behavior of the laterally loaded raker-pile system on sloping sites. Therefore, to address this knowledge gap, the current investigative research paper aimed to study the results of a series of static lateral load tests were conducted in the laboratory on a single aluminium model raker pile embedded in loose sandy soil on 1V: 2H sloping ground. The loading directions were varied considering either forward (close to the slope) or reverse (away from the slope) loading for all pile positions. The influence of the sloping ground was quantified by measuring the pile response for horizontal ground conditions. It was observed that there is a significant increase in the displacement of the pile for the sloping ground surface compared to the horizontal ground. With an increase in the edge distance from the slope crest towards the embankment, a reduction in the pile displacement was observed. The optimum distance from the slope crest towards the embankment where the effect of slope becomes nullified under both forward and reverse lateral loads was determined as 10D (D – Diameter of the pile). From the obtained results, it was evident that in the case of the level ground and sloping ground with forward loading, the negative raker piles offer more resistance to lateral loads than vertical piles. In contrast, the positive raker piles endure the least lateral load with increasing inclination angle.

Finite-Element Analysis of the Lateral Load Response of Monopiles in Layered Sand

Most of the existing design methods for laterally loaded monopiles were developed for uniform soil profiles. The application of such design methods in cases involving layered sand profiles can lead to incorrect capacity estimations. In order to investigate the impact of the soil layering on the response of monopiles to lateral loads and to develop a design method that is applicable to layered soil profiles, a series of three-dimensional (3D) finite-element (FE) analyses were performed on laterally loaded monopiles embedded in layered sand profiles using an advanced two-surface-plasticity constitutive model. The analyses take into consideration a wide range of pile geometries (pile diameter, slenderness ratio, and wall thickness), load eccentricities, sand types and relative densities, and layered soil profiles. The study examines the change of the lateral capacity of a monopile in a two-layer sand profile as the top layer thickness varies, as well as the impact of the presence of a thin loose-sand layer in a dense-sand profile on the pile lateral capacity. Based on the results of these analyses, a set of design equations is proposed to estimate the lateral capacity and load-rotation response of monopiles in layered sand profiles. The proposed method accounts for the 3D pile–soil interaction and provides estimates of the lateral capacity that are in close agreement with those obtained from the 3D FE analyses.

Three-dimensional scour hole model and scour effects on the ultimate capacity of lateral loaded rigid piles

The rigid pile with a large diameter and a small slenderness ratio is the most widely used foundation for offshore wind turbines. Scour around piles seriously threatens the safe operation of offshore wind turbines, so its effects on rigid piles need to be studied urgently. In this paper, scour tests under steady current and static lateral load tests after scour are conducted. According to the results of scour tests, a three-dimensional scour hole model suitable for engineering reality and its analytical expression are proposed. Then, the results of load tests indicate that scour reduces the ultimate lateral capacity of foundations, and the percentage of reduction is related to the current direction, whereas does not change with load eccentricity. Finally, a preliminary formula for evaluating the ultimate lateral capacity of rigid piles after scour is presented, which can easily and quickly determine the upper and lower limits of scour effects.

Robust Analysis and Design of Bored Pile Considering Uncertain Parameters

Many high-rise buildings and bridges in the worlds are constructed using bored pile. To provide a safe design of this type of deep foundation, high-quality soil data are needed which are normally obtained from laboratory testing. However, the contractor and the consultant often conduct only a limited field testing without performing laboratory tests. As a result, the capacity of bored pile may deviate from the real value. This study aims to develop a framework for analysis and design of axial and lateral capacity of bored piles when only a few soil parameters are known. The proposed methodology uses analytical methods backed by numerical calculations according to relevant code of practice. The results indicate that as long as the analytical results are supported by the numerical calculations, a robust design can be achieved with only a few soil parameters: a standard penetration test and a cone penetration test.

Experimental and Numerical Study on the Winged Pile-Soil Interaction under Lateral Loads

Increasing the cross-sectional area of piles leads to an increase in the lateral bearing resistance and reduces displacements near ground level. This increase compensates for the reduction in soil stiffness at the seabed level. Installing wings near the mudline level is one approach for increasing the area of the pile in mudline level. This research paper discusses a number of small-scale laboratory models and FEM models to study the benefit of adding wings on the variation of bearing capacity of laterally pile loaded embedded in sandy soil. To determine the advantages of adding wings to the pile, four embedded ratios (4, 6, 8, 10) were used to model both flexible and rigid pile types with various wing numbers and dimensions. The results revealed that adding wings to the pile improves lateral load resistance and greatly reduces lateral deflection. So, to achieve better resistance, wings must be linked with the pile shaft perpendicular to the lateral load applied nearer the top of the pile head. Increasing the number of wings results in a large increase in lateral pile capacity. The ultimate lateral applied load is proportional to the rise in relative density at the same (L/D) ratio.

Lateral behavior of monopiles considering the effects of sand subsidence and densification under lateral cyclic loading

The deformation characteristics (namely, subsidence and densification) of sandy soil surrounding piles under lateral cyclic loading has become a major research topic. The behavior of soil subsidence reduces the embedded depth of monopiles and increases the bending moment of the pile head, which causes reduction of the piles’ lateral capacity. In contrast, soil densification results in stiffening effect, which can increase the lateral capacity of monopiles. In this study, first, the changes of pile-soil system parameters caused by subsidence and densification are quantified based on the mass conservation principle of the subsidence zone and densification region. Then, lateral responses of monopiles before and after cycling are investigated by American Petroleum Institute (API) p-y curve model. The effects of the subsidence dimensions, initial relative densities and densification region modes (Mode 1 and Mode 2) on the pile lateral responses are analyzed. Lastly, a simple framework is proposed to evaluate the pile lateral capacity after cycling. Salient findings of this study are: (i) The lateral capacity of monopiles increases with the increment of subsidence dimension; (ii) The effect of cyclic loading on the lateral capacity of monopiles gradually decreased with the increase of initial relative densities; (iii) The significant nonlinear relationship between improvement ratio of pile lateral capacity and subsidence dimension revealed that Mode 2 agreed better with the actual conditions compared with Mode 1.

Lateral load response of large-diameter monopiles in sand

Due to the increasing demand for renewable clean energy, there has been rapid growth in the development of offshore wind energy resources in recent years. The majority of offshore wind turbines are founded on single, large-diameter, open-ended pipe piles known as monopiles. The design of these piles is often done using the p–y method, which models the soil simply as non-linear springs placed along the pile length and assumes the pile to behave as a one-dimensional beam. To develop a design method that accounts for three-dimensional pile–soil interaction and that is applicable to general conditions, a series of finite-element (FE) analyses covering a wide range of pile dimensions, wall thicknesses, slenderness ratios, load eccentricities, sand types and sand relative densities were performed using an advanced sand constitutive model. In this paper, a set of equations is proposed that can be used to estimate the critical pile length, Lcrit (the pile length beyond which the pile lateral capacity no longer increases), the lateral capacity, H, and the lateral load–rotation curve for monopiles. The proposed method produces estimates of the lateral capacity of monopiles that are in very close agreement with those from the FE analyses.

Effect of slope on bearing capacity of laterally loaded pile based on asymmetric failure mode

An asymmetric failure mode of soil in front of laterally loaded piles at the slope crest is presented to estimate the pile bearing capacity in this study. The effect of soil shear strength below the rotation center is taken into account by postulating the suppositional sliding curve and corresponding mobilization coefficient of soil strength. Subsequently, the soil resistances above the rotation center at soil failure can be obtained by upper bound theorem of limit analysis. Employing static equilibrium equations, the analytical solution of lateral bearing capacity of piles is assessed by adopting the concept of effective embedment depth. The analytical solution, considering the the slope effect on limiting force profile, is then validated by numerical predictions and full-scale tests. Furthermore, a non-dimensional coefficient, capacity ratio, is proposed to characterize the slope effect on the bearing capacity of laterally loaded piles, and the range of capacity ratio for different internal friction angles are differentiated as different distribution areas. The effect of distance between the pile and slope crest on pile bearing capacity is further investigated, and the capacity ratios appear to be approximatively linear with normalized distance λ and would increase to 1 until λ exceeds the critical value.

An Experimental Study on Laterally Loaded Winged Pile in Sandy Soil

Many offshore facilities such as offshore wind turbines and other engineering structures, including floating offshore facilities (FPSOs), are founded on or anchored with piles to transfer large horizontal loads relative to the imposed vertical load compared to onshore installations. The subgrade reaction of the soil surrounding the pile shaft mobilized when the lateral loading is applying on the pile to resist the applied loads. Since the soil at the midline is often weak and tends to have a poor subgrade reaction, resulting in large pile displacements near ground level. The lateral bearing capacity of pile foundations can be increased, and pile displacements near ground level can be decreased by expanding the piles’ cross-sectional area near the seabed level to compensate for the lower soil stiffness in the seabed level. One method of expanding the pile area in the lower soil stiffness zone is the addition of wings (or fins) near the seabed level. This paper presents a series of laboratory small-scale model tests that were conducted to laterally loaded piles with/without wings in sandy soil with different densities. The Piles slenderness’s ratio (L/D) is varied from 4, 6, 8, and 10 to simulate the behavior of both flexible and rigid pile designs, with different wings geometry and numbers. This study indicated that the lateral pile capacity increased, and the horizontal deformation of the pile decreased after mounting wings compared to the regular normal pile without wings. It has been found that the optimum geometry and number of adopted wings is found to be three wings, and its length equals (0.22) of the embedded pile length. The existence of wings improved the bearing capacity of the winged pile by 1.33, 1.18, and 1.16 for piles of L/D=10 in the case of loose, medium, and dense soils, respectively, compared to regular piles in the same condition.

The Behavior of Piles Installed in Medium Dense Sand Within MSE Wall System

Mechanically Stabilized Earth Walls (MSE) were widely used in several essential infrastructures, such as the abutments on a bridge. The need for a support base of a shallow or a deep bridge increased in the MSE wall system. In this research, factors affecting the performance of laterally loaded piles embedded in medium dense sand with a relative density of 50% behind an MSE wall were studied using lower-scale models in the laboratory. For instance, the effect of pile offset and the slenderness ratio on the pile's lateral capacity and pressure on the MSE wall. Three different slenderness ratios were introduced (i.e. L/D of 19.3, 21.7, and 24.1). The results showed a significant increase in pile lateral capacity occurring with the increase in pile offset or slenderness ratio (i.e., L/D). While increasing the pile offset reduced, the pressure on the wall so that the wall's effect will be insignificant when the pile offset reaches a value of 6D.

Service Life Prediction and Lateral Bearing Capacity Analysis of Piles Considering Coupled Corrosion-Temperature Deterioration Processes

High temperatures can enhance the chloride diffusion coefficient and this poses a threat to reinforced concrete (RC) piles. This study intends to propose predictive models that can evaluate the service life and lateral bearing behaviour of reinforced concrete piles subjected to marine environments and varying temperatures. The models show that temperature can accelerate the diffusion rate of chloride and increase the concentration of free chloride in concrete. The distribution law of chloride concentration is obtained by considering the ageing effect as well. Deterministic and probabilistic models are proposed to assess the time to corrosion initiation and propagation. The stiffness degradation coefficient is introduced in the analysis of the lateral bearing capacity of RC piles. The results show that high temperature can decrease the service life of piles and the life spans obtained from deterministic and probabilistic methods are similar; however, the predictions of the latter are more conservative. Temperature can enhance the current density and boost corrosion products, which leads to pile cracking. The rust appearing on the steel surface would make the stiffness degradation coefficient drop sharply. The lateral bearing capacity analysis is conducted from the perspectives of shear force, displacement and bearing moment of the piles.