Lateral Load Capacity Of Piles Research Articles

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.

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.

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.

Laboratory Study of Lateral Load Capacity and Behaviour of Short Piles in Clayey Soil.

This research is an experimental study investigating the lateral loading capacity of piles in clayey soil. Important factors considered in this study included pile diameter, embedded length of pile, effective unit weight, and degree of saturation of soil, which were studied for their effects on the lateral loading capacity of short driven piles. The experimental study involved testing six specimens in the laboratory, each made of galvanized iron of 21.7 and 27 mm diameter and L/d (embedded length/diameter) ratios of 10, 14, and 18. The specimens were subjected to lateral loadings while embedded in clayey soil with effective unit weights of 13, 15, and 15.6 kN/m3 and degrees of saturation of 30, 41 and 97%, to simulate true pile behaviour. The obtained pile responses were then plotted as force-displacement diagrams. The varying parameters were thus diameter and embedded depth of pile, effective unit weight, and degree of soil saturation. The results of this experimental study on the behaviours of the piles under the influence of lateral loading in the clay were also compared with the predicted lateral capacity of the piles based on work by other researchers. Moisture content and degree of saturation were found to have the greatest effects on pile behaviour. This study thus aids understanding of the behaviours of short piles embedded in clayey soil under lateral loading to allow designers to take practical steps and choose an appropriate method when designing a pile.

Lateral Load Capacity of Piles: A Comparative Study Between Indian Standards and Theoretical Approach

As per Indian Standards, laterally loaded piles are usually analysed using the method adopted by IS 2911-2010 (Part 1/Section 2). But the practising engineers are of the opinion that the IS method is very conservative in design. This work aims at determining the extent to which the conventional IS design approach is conservative. This is done through a comparative study between IS approach and the theoretical model based on Vesic’s equation. Bore log details for six different bridges were collected from the Kerala Public Works Department. Cast in situ fixed head piles embedded in three soil conditions both end bearing as well as friction piles were considered and analyzed separately. Piles were also modelled in STAAD.Pro software based on IS approach and the results were validated using Matlock and Reese (In Proceedings of fifth international conference on soil mechanics and foundation engineering, 1961) equation. The results were presented as the percentage variation in values of bending moment and deflection obtained by different methods. The results obtained from the mathematical model based on Vesic’s equation and that obtained as per the IS approach were compared and the IS method was found to be uneconomical and conservative.

Ultimate Lateral Load Capacity of Piles in Soils Contaminated with Industrial Wastewater

The present study devoted to determine the ultimate lateral carrying capacity of piles foundation in contaminated clayey soils and subjected to lateral cyclical loading. Two methods have been used to calculate the lateral carrying capacity of piles foundation; the first one is two-line slopes intersection method (TLSI) and the second method is a modified model of soil degradation. The model proposed by Heerama and then developed by Smith has been modified to take into consideration the effects of heavy loads and soil contamination. The ultimate lateral carrying capacity of single pile and piles group (2×2) driven into samples of contaminated clayey soils have been calculated by using the two methods. Clayey soil samples are contaminated with four percentages of industrial wastewater (10, 20, 40 and 100) % of the distilled water used in the soaking process, the soaking procedure of soil samples have been proceeded for 30 days. Also, two ratios of eccentricity to embedded length (e/L = 0.25 and 0.5) have been examined. The results obtained from two analytical methods are well agreed with those obtained experimentally. The ultimate lateral carrying capacity, Pu (analytical) /Pu (experimentally) ranged from (75-8) % and (77-80) % of single pile with e/L = 0.25 and 0.5 respectively. In the piles group the ratio ranged (67-80) % and (71-79) % for e/L = 0.25 and 0.5 respectively.

Influence of sloping ground on lateral load capacity of single piles in clayey soil

In many practical situations, structures subject to lateral loading are located near slopes. The presence of a slope on deep foundations loaded in a downslope direction can decrease the overall lateral capacity of the system. In this paper, the effect of soil slope, undrained cohesion, pile–soil interface adhesion, pile diameter and pile cap on the lateral load carrying capacity of pile located at the crest of clay slope is studied using PLAXIS-3D. Clay is modelled as linearly elastic perfectly plastic Mohr–Coulomb material, whereas pile is modelled as a linear elastic material. Formation of gap on the extension side of pile–soil interface is also considered. Lateral load capacity of pile for a corresponding prescribed displacement of 5 mm is estimated. An equation to determine the value of lateral pile capacity in terms of undrained cohesion, pile diameter and pile–soil interface adhesion has been formulated from the results.

Prediction of Lateral Load Capacity of Pile in Clay Using Multivariate Adaptive Regression Spline and Functional Network

This paper discusses the use of multivariate adaptive regression splines (MARS) and functional networks (FN) for prediction of the lateral load capacity of piles in clay. The results obtained from MARS and FN have been compared with different empirical models and artificial neural network in terms of statistical parameters such as correlation coefficient (R), Nash–Sutcliff coefficient of efficiency (E), absolute average error, maximum average error and root mean square error. Based on the statistical parameters, MARS and FN were found to have a better predictive capacity. Predictive equations are provided based on the MARS and FN model. A sensitivity analysis is also presented to determine the importance of inputs in prediction of the lateral load capacity of piles.

Lateral Load Capacity of Piles in Clay Using Genetic Programming and Multivariate Adaptive Regression Spline

This study presents the development of predictive models of lateral load capacity of pile in clay using artificial intelligence techniques; genetic programming and multivariate adaptive regression spline. The developed models are compared with different empirical models, artificial neural network (ANN) and support vector machine (SVM) models in terms of different statistical criteria. A ranking system is presented to evaluate present models with respect to above models. Model equations are presented and are found to be more compact compared to ANN and SVM models. A sensitivity analysis is made to identify the important inputs contributing to the lateral load capacity of pile.

Prediction of lateral load capacity of piles using extreme learning machine

This study presents the development of a predictive model for the lateral load capacity of pile in clay using an artificial intelligence technique, extreme learning machine (ELM). Other artificial intelligence models like artificial neural networks (ANN) (Bayesian regularization neural network (BRNN), differential evolution neural network (DENN)) are also developed to compare the ELM model with them and available empirical models in terms of different statistical criteria. A ranking system is presented to evaluate the present models for identifying the “best” model. Sensitivity analyses are made to identify important inputs contributing to the developed models.

Least square support vector machine and multivariate adaptive regression spline for modeling lateral load capacity of piles

This article adopts least square support vector machine (LSSVM) and multivariate adaptive regression spline (MARS) for prediction of lateral load capacity (Q) of pile foundation. LSSVM is firmly based on the theory of statistical learning, uses regression technique. MARS is a nonparametric regression technique that models complex relationships. Diameter of pile (D), depth of pile embedment (L), eccentricity of load (e), and undrained shear strength of soil (Su) have been used as input parameters of LSSVM and MARS. Equations have been presented from the developed MARS and LSSVM. This study also presents a comparative study between the developed MARS and LSSVM.

Estimation of Ultimate Lateral Load Capacity of Piles in Sands Using Calibration Chamber Tests

Abstract Current practice for the estimation of the ultimate lateral load capacity of piles is typically based on the vertical effective stress σ′v, while the effect of the lateral effective stress σ′h is not specifically considered. In the present study, calibration chamber lateral pile load tests are conducted to investigate the load response and ultimate lateral load capacity Hu of laterally loaded piles under various soil and stress conditions. In order to determine Hu from load-deflection curves, different criteria are explored and analyzed. From the test results, it is shown that Hu increases significantly with increasing σ′h for a given σ′v. It is also found that lateral deflection of pile at ultimate state tends to increase as the relative density and lateral stress increase. On the basis of the test results, the lateral stress correction factor reflecting the effect of the lateral effective stress σ′h on Hu is proposed. From the test results, it is seen that the proposed procedure using the lateral stress correction factor produces more realistic estimation of Hu. Case examples are selected from the literature and used to compare results measured and predicted using the proposed approach.

Head embedment in Broms pile lateral capacity theory for cohesionless soils

The method by Broms for the evaluation of lateral load capacity of piles and shafts is well known to every geotechnical engineer and still used nowadays, at least in some simple situations. It applies to piles with a restrained head at the ground level, or a free head at or above the ground, both for cohesive and cohesionless soils. In this paper the Broms theory for cohesionless soils is extended to account for an arbitrary position of the pile head, considering embedded as well as over-ground restrained and free pile head. Explicit analytic expressions for the collapse load and the geometrical parameters of the problem are given, making use of the geometric approach by Nickalls to the solution of the cubic equation. The relationships between embedding and over-ground situations on one hand, and restrained and free head cases on the other are discussed, some simplified calculation procedures being suggested.

A new multi-gene genetic programming approach to non-linear system modeling. Part II: geotechnical and earthquake engineering problems

Complexity of analysis of geotechnical behavior is due to multivariable dependencies of soil and rock responses. In order to cope with this complex behavior, traditional forms of engineering design solutions are reasonably simplified. Incorporating simplifying assumptions into the development of the traditional methods may lead to very large errors. This paper presents an endeavor to exploit a robust multi-gene genetic programming (MGGP) method for the analysis of geotechnical and earthquake engineering systems. MGGP is a modified genetic programming approach for model structure selection combined with a classical technique for parameter estimation. To justify the abilities of MGGP, it is systematically employed to formulate the complex geotechnical engineering problems. Different classes of the problems analyzed include the assessment of (i) undrained lateral load capacity of piles, (ii) undrained side resistance alpha factor for drilled shafts, (iii) settlement around tunnels, and (iv) soil liquefaction. The validity of the derived models is tested for a part of test results beyond the training data domain. Numerical examples show the superb accuracy, efficiency, and great potential of MGGP. Contrary to artificial neural networks and many other soft computing tools, MGGP provides constitutive prediction equations. The MGG-based solutions are particularly valuable for pre-design practices.

모래지반에서 재하방법이 반복수평하중을 받는 말뚝의 거동에 미치는 영향

The behavior of laterally cyclic loaded piles is affected by the magnitude and number of cycles of cyclic lateral loads as well as loading method (1-way or 2-way loading). In this study, calibration chamber tests were carried out to investigate the effects of loading method of cyclic lateral loads on the behavior of piles driven into sand. Results of the chamber tests show that the permanent lateral displacement of 1-way cyclic loaded piles is developed in the same direction as the first loading, whereas that of 2-way cyclic loaded piles is developed in the reverse direction of the first loading. 1-way cyclic lateral loads cause a decrease of the ultimate lateral load capacity of piles, and 2-way cyclic lateral loads cause an increase of the ultimate lateral load capacity of piles. The change of ultimate lateral load capacity with loading method of cyclic lateral loads increases with increasing number of cycles. It is also observed that the 1-way cyclic loads generate greater maximum bending moment than 2-way cyclic loads for piles in cyclic loading step and generates smaller maximum bending moment for piles in the ultimate state. It can be attributed to the difference in compaction degree of the soil around the piles with loading method of cyclic lateral loads. In addition, it is founded that 1-way and 2-way cyclic lateral loads cause a decrease in the maximum bending moment of piles in the ultimate state compared with that of piles subjected to only monotonic loads.

Undrained lateral load capacity of piles in clay using artificial neural network

This paper describes the application of the artificial neural network model to predict the lateral load capacity of piles in clay. Three criteria were selected to compare the ANN model with the available empirical models: the best fit line for predicted lateral load capacity ( Q p) and measured lateral load capacity ( Q m), the mean and standard deviation of the ratio Q p/ Q m and the cumulative probability for Q p/ Q m. Different sensitivity analysis to identify the most important input parameters is discussed. A neural interpretation diagram is presented showing the effects of input parameters. A model equation is presented based on neural network parameters.

The limiting pressure on a circular pile loaded laterally in cohesive soil

In the analysis of the undrained loading of laterally loaded piles an important quantity is the ultimate lateral resistance at depth to purely horizontal movement. If the soil is modelled as a perfectly plastic cohesive material then the calculation of this quantity reduces to a plane strain problem in plasticity theory, in which the load is calculated on a long cylinder which moves laterally through an infinite medium. An exact calculation of the load on such a cylinder is presented. If this load is non-dimensionalized with respect to the soil strength and the diameter of the pile, it is found that the load factor varies between for a perfectly smooth pile and for a perfectly rough pile. This result is discussed in the context of previous calculations for the lateral load capacity of piles and is compared with approximate calculations using cavity expansion theory and a wedge failure near the soil surface. La résistance latérale limite en profondeur au seul mouvement horizontal représente un paramètre important de l'analyse du chargement non-drainé des pieux chargés latéralement. Si le sol est modelisé comme une matériau cohérent parfaitement plastique le calcul de ce paramètre devient un problème de déformation plane dam la théorie de la plasticité, dans laquelle la charge se calcule sur un long cylindre qui se déplace latéralement dans un milieu infini. L'article presente un calcul prtcis de la charge d'un tel cylindre. Si cette charge est rendue sans dimensions eu égard à la résistance du sol et du diamètre du pieu on trouve que le facteur de chargement varie entre pour un pieu parfaitement lisse et pour un pieu parfaitement rugueux. L'article discute ce résultat dans le contexte des calculs précédents de la capacité de chargement des pieux et le compare avec des calculs approximatifs employant la theorie de l'expansion des cavités et un coin de rupture prés de la surface du sol.

Lateral Load Capacity of Piles In Offshore Structures

In evaluating lateral load capacities of piles, three types of interaction are taken into account: between pile and soil, between pile and jacket structure, and between wave and structure. These interactions are normally analyzed individually. The trick is to piece them together. Here is an explanation of how that can be done and an example involving a fixed drilling platform in 350 feet of water. Introduction Offshore structures are installed today in areas of deeper and deeper water. As the platforms become higher and structure masses increase, more accurate and reliable calculations are necessary. The pile-capacity problem is commonly approached by pile-capacity problem is commonly approached by considering the structure in two parts: a linear part (structure above the jacket base) and a nonlinear part (piles and conductors below the jacket base and supported by the soil). The description of interaction between the two parts is often based on poor and incomplete parts is often based on poor and incomplete compatibility conditions. In pile analysis the boundary condition at the cut-off level is a pile-moment-rotation ratio (clockspring). However, neglecting the jacket deformation will influence the results of the pile analysis considerably. In general, for limited water depths this neglect will give conservative results. The bending pile moment occurring at jacket-base level will increase where a stiffer pile-jacket connection is assumed. In these shallower depths the moment governs at the jacket-base level. In deeper waters, however, the maximum moment will occur below the mud line owing to the release of the pile-jacket connection for higher structures, and the maximum moment will decrease when a stiffer pile-jacket connection is assumed. Moreover, the lateral pile deflections will decrease and this may influence the dynamic behavior as well. Another point is that in principle the platform analysis is often deterministic and based on a single storm wave load. This approach, however, is satisfactory only if the natural frequencies of the structure are out of the frequency range of wave energy. For platforms in deeper water this condition is no longer platforms in deeper water this condition is no longer fulfilled. In this paper we shall emphasize the two aspects mentioned above - i.e., random-wave-load description instead of single wave load, and a proper specification of the compatibility conditions between piles and jacket. Fig. 1 shows the relationship of the piles and jacket. Fig. 1 shows the relationship of the components involved. Description of the Analysis The structural analysis of the entire structure can be symbolized by the models in Fig. 2. The structure is split in two main parts: - The piles and conductors below the base of the jacket - The jacket including the piles and conductorsabove the base of the jacket (piles connected to the jacket top). Each of these parts is influenced by its environment. The piles and conductors below the mud line are surrounded by soil, which acts as a supporting medium laterally and axially. The jacket is surrounded by the sea, which may cause wave and current action. Now step by step the interaction between piles and soil, between piles and jacket, and finally between structure and waves piles and jacket, and finally between structure and waves will be analyzed. JPT P. 487