Analysis of laterally loaded piles with rectangular cross sections embedded in layered soil (original) (raw)
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A new framework for analysis of laterally loaded piles
A new analysis framework is presented for calculation of the response of laterally loaded piles in multi-layered, heterogeneous elastic soil. The governing differential equations for the pile deflections in different soil layers are obtained using the principle of minimum potential energy after assuming a rational soil displacement field. Solutions for the pile deflection are obtained analytically, while those for the soil displacements are obtained using the finite difference method. The input parameters needed for the analysis are the pile geometry, soil profile and the elastic constants of the soil and pile. The method produces results with accuracy comparable to that of a three-dimensional finite element analysis but requires much less computation time. The analysis can take into account the spatial variation of soil properties along vertical, radial and tangential directions.
A new model for analysis of laterally loaded piles
A new analysis is developed to calculate the response of laterally loaded piles in multi-layered elastic media. The governing differential equations for pile deflections in different soil layers are derived using energy principles, and solutions are obtained analytically. The displacement fields in the soil surrounding the pile are taken to be the products of independent functions that vary in the vertical, radial and circumferential directions. The input parameters needed for the analysis are the pile geometry, soil profile and the elastic constants of the soil and pile. The method produces results with accuracy comparable to that of a three-dimensional finite element analysis but requires much less computational time.
Continuum-based analyses for laterally loaded piles with rectangular and circular cross sections are presented using solutions that can be obtained quickly without requiring any elaborate inputs for the geometry and numerical mesh. The analysis is developed by solving the differential equations governing the displacements of the pile-soil system derived using the variational principles of mechanics. Parametric studies are performed to investigate the influence of the pile cross-sectional shape, soil layering, pile slenderness ratio, and pile-soil modulus ratio on the response of laterally loaded piles in heterogeneous soil in which the soil shear modulus varies continuously or discretely with depth. The results show that piles with the same second moment of inertia have similar lateral-load response. The lateral responses of piles in two-layer systems were mainly affected by the thickness and stiffness of the top soil layer. Soil layering also influences the lateral response of piles in three-layer soil deposits consisting of two thin layers overlying the third layer. Algebraic equations for estimating the pile-head deflection and maximum bending moment are proposed that can be readily used in design. A user-friendly spreadsheet program is developed as a tool to perform calculations of pile response using the analysis. Numerical examples demonstrating the use of the analysis are provided.
Analysis of Laterally Loaded Piles in Multilayered Soil Deposits
Joint Transportation Research …, 2008
This report focuses on the development of a new method of analysis of laterally loaded piles embedded in a multi-layered soil deposit treated as a three-dimensional continuum. Assuming that soil behaves as a linear elastic material, the governing differential equations for the deflection of laterally loaded piles were obtained using energy principles and calculus of variations. The differential equations were solved using both the method of initial parameters and numerical techniques. Soil resistance, pile deflection, slope of the deflected pile, bending moment and shear force can be easily obtained at any depth along the entire pile length. The results of the analysis were in very good agreement with three-dimensional finite element analysis results. The analysis was further extended to account for soil nonlinearity. A few simple constitutive relationships that allow for modulus degradation with increasing strain were incorporated into the analysis. The interaction of piles in groups was also studied.
Elastic analysis of laterally loaded rectangular piles
An analysis is developed to determine the response of laterally loaded piles with rectangular cross sections. Soil displacement fields compatible with the rectangular shape of the pile cross section are assumed. The differential equations governing the displacements of the pile-soil system are developed using energy principles. Closed-form solutions for lateral pile deflection and displacements within the soil mass can be obtained using the analysis. The input parameters needed for the analysis are the pile geometry and the elastic constants of the soil and pile. The new analysis allows insights into the lateral load response of square, rectangular and circular piles and how they compare.
Variational elastic solution for axially loaded piles in multilayered soil
International Journal for Numerical and Analytical Methods in Geomechanics, 2013
Most 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. and provides useful insights into the displacement and strain fields around axially loaded piles. We compare the results from the analysis presented in this paper with those from the solution of Seo and Prezzi . We also show through an example problem that there is reasonably good agreement between the results from finite element analysis and the analysis presented in this paper for piles installed in multilayered elastic soil.
Axially loaded vertical piles and pile groups in layered soil
International Journal for Numerical and Analytical Methods in Geomechanics, 1991
A numerical method is described for the analysis of axially loaded vertical piles and pile groups embedded in layered soil. The 'hybrid approach is utilized whereby the single-pile response is represented by load-transfer (1-2) curves while the pile-soil-pile interaction is obtained accurately using the analytical solutions of Chan et a!. for a two-layered system and in an approximate manner for a Gibson soil. For the single-pile response a simple rational procedure is suggested for the determination of the averaged rm value (radial distance at which the shear stress becomes negligible). Solutions are presented and compared with the elastic continuum solutions for such soil profiles. Finally, comparisons with actual field measurements of vertical piles and pile groups embedded in such a soil profile show favourable agreement.
A framework for analysis of piles with rectangular cross section
An analysis framework is presented for piles with rectangular cross section. Existing analysis and design methods are mostly applicable for piles with circular cross section. For piles with cross section other than a circle, an equivalent circle is often assumed and the methods for circular piles are applied. The newly developed framework explicitly takes into account the rectangular cross section and produces the response of piles under axial and lateral loads. A rational soil displacement field surrounding the rectangular cross section of the pile is assumed, and the total potential energy of the loaded pile-soil system is considered. The potential energy is minimized using calculus of variations to obtain the differential equations governing the pile and soil displacements. Closed-form solutions are obtained for pile settlement and axial force in the case of axially loaded piles. For laterally loaded piles, closed-form solutions are obtained for lateral deflection, slope of the deflected curve, pile bending moment and shear force. The input parameters needed for the analysis are the pile geometry, applied load and the elastic constants of the soil and pile. The new analysis framework produces results in seconds and has the accuracy of equivalent three-dimensional finite element analysis. 558 From Soil Behavior Fundamentals to Innovations in Geotechnical Engineering Downloaded from ascelibrary.org by University of Waterloo on 08/03/15. Copyright ASCE. For personal use only; all rights reserved. From Soil Behavior Fundamentals to Innovations in Geotechnical Engineering Downloaded from ascelibrary.org by University of Waterloo on 08/03/15.
Effect of the Non-Linear Behavior of Pile Material on the Response of Laterally Loaded Piles
2001
The main purpose of this study is to assess the lateral response of piles/shafts and the p-y curves for different soil-pile combinations while introducing the effect of the moment-curvature (M-0) relationship of the pile into the soil-pile interaction. Therefore, the equilibrium among soil reaction, pile deflection pattern, pile-head load, and flexural stiffness distribution should be satisfied at any level of loading. The influence of the nonlinear behavior of the pile/drilled shaft material on the nature of the associated p-y curve is presented through strain wedge (SW) model analysis. The SW model allows the assessment of the (soil-pile) modulus of subgrade reaction (i.e. the p-y curve) based on soil and pile properties which includes the pile bending stiffness. Therefore, the assessed modulus of subgrade reaction will be affected by changes in the bending stiffness of the pile or drilled shaft at any pile cross section (via the M-Q relationship). The reduction in pile bending stiffness will affect the pile-head stiffness under varying static or dynamic loading.