Piles In Multilayered Soil Research Articles

Evaluation of Overall Response of Driven Pile in Multi-layered Soil

Evaluation of Overall Response of Driven Pile in Multi-layered Soil

Analytical solution for laterally loaded non-uniform circular piles in multi-layered inhomogeneous soil

ABSTRACT Non-prismatic piles are typically used in cases where large lateral loads must be resisted. In many applications, piles are partially or fully embedded in multi-layered non-homogeneous soil, with each layer having its own set of properties. Analytical, simple solutions to study this problem are more limited and complex than that of prismatic ones. The analysis becomes even more complicated when both the variation of the cross-sectional area of the element and the soil inhomogeneity are included in the formulation. This work presents the derivation of the stiffness matrix and load vector of a non-uniform section of pile partially or fully embedded in non-homogeneous soil. The analysis of non-uniform piles in multi-layered soil is carried out by dividing the pile into multiple sub-elements and then assembling them using conventional matrix methods. Four examples, encompassing partially and fully embedded piles, are presented to validate the simplicity and accuracy of the proposed solution.

Stiffness matrix method for analysis of torsionally loaded piles in multi-layered soil

A new, simple and practical method to investigate the response of torsionally loaded piles on homogeneous or non-homogeneous multi-layered elastic soil was developed. Soil non-homogeneity is accounted for by assuming, for each layer, a shear modulus distribution that fits a quadratic function. Analysis of piles in multi-layered soil is carried out by subdividing the pile, at the soil–soil layer and soil–air interfaces, into multiple elements and then using conventional matrix methods – such as those commonly implemented in structural analysis – to connect them. The governing differential equation of an individual structural element is solved using the differential transformation method. The stiffness matrix is then derived by applying compatibility conditions at the ends of the element. Piles partially or fully embedded in multiple layers and subjected to torsion can be analysed in a simple manner with the proposed formulation – a tedious endeavour with other available solutions. Explicit expressions for the coefficients of the matrix are provided and four examples are presented to show the simplicity, accuracy and capability of the proposed formulation.

Timoshenko Beam Theory–Based Dynamic Analysis of Laterally Loaded Piles in Multilayered Viscoelastic Soil

AbstractA semianalytical method is developed to obtain the dynamic response of laterally loaded piles in a multilayered soil. In the analysis, the soil is modeled as a three-dimensional viscoelasti...

Undrained behavior of auger cast-in-place piles in multilayered soil

Auger cast-in-place piles (ACIP) are often installed through multilayered soil profiles, which make accurate predictions of the performance of the piles more complex than piles constructed in either clay or sand deposits. This study is intended to shed some light on the undrained behavior of ACIP embedded in stratified soil and to explore a methodology to predict the ultimate pile loads. The study is based on practical measurements of load–displacement relationships of 51 static loading tests of full-scale ACIP installed through multilayered soil profiles. The study revealed that the normalized load–displacement relationships of the tested piles have deterministic range with upper and lower bounds. Equations for these bounds and the mean load–displacement relationship are developed in this study. There is a deficiency in the literature concerning the calculations of ultimate loads for piles embedded in multilayered soil. Therefore, this paper presents an attempt to estimate the ultimate pile load in undrained conditions utilizing two approaches. The first approach assumed the failure pattern of the soil beneath the pile base to be punching into the sand followed by general shear failure in clay underneath. The end-bearing resistance at the pile tip was estimated by implementing Meyerhof and Hanna’s [24] shallow foundation procedure. The second approach assessed the depth of the influence zone below the pile tip using isobars of pressure around and below the pile tip due to a point load, based on the theory of elasticity and characterization of a semi-infinite soil mass (Martins [3]). Soil layers, within the zone of influence, were considered to be an equivalent geomaterial with shear strength parameters computed by weighted average of shear strength parameters of the soil sub-layers. For comparison purposes, the ultimate pile load of each test was interpreted experimentally using the method proposed by Chin (1970). Reasonable agreement was obtained between the predicated and the experimental values, with an accuracy of about ±17%.

Variational elastic solution for axially loaded piles in multilayered soil

SUMMARYMost analytical or semi‐analytical solutions of the problem of load‐settlement response of axially loaded piles are based on the assumption of zero radial displacement. These solutions also are only applicable to piles embedded in either a homogeneous or a Gibson soil deposit. In reality, soil deposits consist of multiple soil layers with different properties, and displacements in the radial direction within the soil deposit are not zero when the pile is loaded axially. In this paper, we present a load‐settlement analysis applicable to a pile with circular cross section installed in multilayered elastic soil that accounts for both vertical and radial soil displacements. The analysis follows from the solution of the differential equations governing the displacements of the pile–soil system obtained using variational principles. The input parameters needed for the analysis are the pile geometry and the elastic constants of the soil and pile. We compare the results from the present analysis with those of an analytical solution that considers only vertical soil displacements. The analysis presented in this paper also provides useful insights into the displacement and strain fields around axially loaded piles. Copyright © 2011 John Wiley & Sons, Ltd.

Load-Settlement Response of Rectangular and Circular Piles in Multilayered Soil

Traditionally, analyses developed for circular piles have also been used for rectangular piles by replacing in calculations the rectangular pile with a circular pile of equivalent area. In this paper, we present a settlement analysis that applies to piles with either rectangular or circular cross sections installed in multilayered soil deposits. The analysis follows from the solution of the differential equations governing the displacements of the pile-soil system obtained using variational principles. The input parameters needed for the analysis are the pile geometry and the elastic constants of the soil and pile. Pile displacements and vertical soil displacements calculated using this analysis match well those from finite-element analysis. A parametric study highlights some important insights for rectangular and circular piles in multilayered soil. A user-friendly spreadsheet program (ALPAXL) was developed to facilitate the use of the analysis. Examples illustrate the use of the analysis in design.

Elastic analysis of laterally loaded pile in multi-layered soil

An analysis is developed to determine the response of laterally loaded piles in layered elastic media. The differential equations governing pile deflections in different layers due to a concentrated static force and/or moment acting at the pile head are obtained using the principle of minimum potential energy and calculus of variations. The differential equations are solved analytically using the method of initial parameters. Pile deflection, slope of the deformed axis of the pile, bending moment and shear force can be reliably obtained by this method for the entire pile length. The input parameters needed for the analysis are the pile geometry and the elastic constants of the soil and pile. It is observed that soil layering has a definite impact on pile response and must be taken into account for proper analysis and design. The analysis forms the basis for future formulations that can consider stress–strain nonlinearity.

Analytical solutions for a vertically loaded pile in multilayered soil

Explicit elastic solutions for a vertically loaded single pile embedded in multilayered soil are presented. Solutions are also provided for the case in which the pile base rests on a rigid material. Energy principles are used in the derivation of the governing differential equations. The solutions, which satisfy compatibility of displacement in the vertical and radial directions, were obtained by determining the unknown integration constants using the boundary conditions, Cramer's rule, and a recurrence formula. The solutions provide the pile vertical displacement as a function of depth, the load-transfer curves, and the vertical soil displacement as a function of the radial distance from the pile axis at any depth. The use of the analysis is illustrated for a pile that was load-tested under well-documented conditions by obtaining load–transfer and load–settlement curves that are then compared with those obtained from the load test.

A New Analytical Model for Settlement Analysis of a Single Pile in Multi-Layered Soil

In this study, an extension of the variational model proposed by Vallabhan and Mustafa (1996) for the settlement analysis of an axially loaded pile embedded in a multi-layered soil profile is presented. In this model, the soil profile and the embedded pile are divided into a number of sub-layers according to the actual number of soil layers observed in the field. The displacement shape function of each soil layer is given as the product of an exponential equation along the pile depth and Bessel’s solution in the radial direction. The displacement relationship in each layer can be derived through transformation matrices. One of the major features of this method is that the total number of pile elements is the same as the total number of soil sub-layers. All the field components, such as displacements, stresses, and strains in the soil, can be calculated by closed-form solutions except the only unknown variable, β , which is a variable as expressed by the modified Bessel’s functions of the second kind, and which can be determined by iteration techniques. Comparisons were made with the results of finite element analysis and field pile-loaded tests. Reasonable results were obtained for all cases.