Simplified Analytical Solutions for Tunnel Settlement Induced by Axially Loading Single Pile and Pile Group

2021 ◽  
Vol 147 (12) ◽  
Author(s):  
Yixian Wang ◽  
Jian Liu ◽  
Panpan Guo ◽  
Wei Zhang ◽  
Hang Lin ◽  
...  
Keyword(s):  
Analytical Solutions ◽  
Pile Group ◽  
Single Pile

scholarly journals Influence of the phase difference between kinematic and inertial loads on seismic behaviour of pile foundations in layered soils

2020 ◽  
Author(s):  
Thejesh Kumar Garala ◽  
Gopal Madabhushi
Keyword(s):  
Natural Frequency ◽  
Free Field ◽  
Phase Relationship ◽  
Phase Variation ◽  
Bending Moment ◽  
Pile Group ◽  
Pile Foundations ◽  
Single Pile ◽  
Seismic Behaviour ◽  
Soil Layers

A series of dynamic centrifuge experiments was conducted on model pile foundations embedded in a two-layered soil profile consisted of soft-clay layer underlain by dense sand. These experiments were specifically designed to investigate the individual effect of kinematic and inertial loads on a single pile and a 3×1 row pile group during model earthquakes. It was observed that the ratio of free-field soil natural frequency to the natural frequency of structure might not govern the phase relationship between the kinematic and inertial loads for pile foundations as reported in some previous research. The phase relationship obtained in this study agrees well with the conventional phase variation between the force and displacement of a viscously damped simple oscillator subjected to a harmonic force. Further, as expected, the pile accelerations and bending moments can be smaller when the kinematic and inertial loads act against each other compared to the case when they act together on the pile foundations. This study also revealed that the peak kinematic pile bending moment will be at the interface of soil layers for both single pile and pile group. However, in the presence of both kinematic and inertial loads, the peak pile bending moment can occur either at the shallower depths or at the interface of soil layers depending on the pile cap rotational constraint.

An experimental investigation into pile group-layered soil interaction

1996 ◽  
Vol 31 (5) ◽  
pp. 371-375
Author(s):  
K Chandrashekhara ◽  
S Joseph Antony ◽  
J Mallikarjuna Reddy
Keyword(s):  
Numerical Solutions ◽  
Interaction Analysis ◽  
Pile Group ◽  
Layered Soil ◽  
Single Pile ◽  
Photoelastic Method ◽  
Soil Medium ◽  
Interaction Factor ◽  
Pile Cap ◽  
Soil Interface

An interaction analysis of an axially loaded single pile and pile group with and without a pile cap in a layered soil medium has been investigated using the two-dimensional photoelastic method. A study of the pile or pile group behaviour has been made, varying the pile cap thickness as well as the embedded length of the pile in the hard stratum. The shear stress distribution along the pile-soil interface, non-dimensionalized settlement values of the single pile and the interaction factor for the pile group have been presented. Wherever possible, the results of the present analysis have been compared with available numerical solutions.

Dynamic analysis of laterally loaded pile groups in sand and clay

2002 ◽  
Vol 39 (6) ◽  
pp. 1358-1383 ◽  
Author(s):  
Yasser E Mostafa ◽  
M Hesham El Naggar
Keyword(s):  
Dynamic Loading ◽  
Dynamic Load ◽  
Load Transfer ◽  
Pile Group ◽  
Nonlinear Behaviour ◽  
Single Pile ◽  
Offshore Platforms ◽  
Group Effect ◽  
Pile Groups ◽  
Pile Head

Pile foundations supporting bridge piers, offshore platforms, and marine structures are required to resist not only static loading but also lateral dynamic loading. The static p–y curves are widely used to relate pile deflections to nonlinear soil reactions. The p-multiplier concept is used to account for the group effect by relating the load transfer curves of a pile in a group to the load transfer curves of a single pile. Some studies have examined the validity of the p-multiplier concept for the static and cyclic loading cases. However, the concept of the p-multiplier has not yet been considered for the dynamic loading case, and hence it is undertaken in the current study. An analysis of the dynamic lateral response of pile groups is described. The proposed analysis incorporates the static p–y curve approach and the plane strain assumptions to represent the soil reactions within the framework of a Winkler model. The model accounts for the nonlinear behaviour of the soil, the energy dissipation through the soil, and the pile group effect. The model was validated by analyzing the response of pile groups subjected to lateral Statnamic loading and comparing the results with field measured values. An intensive parametric study was performed employing the proposed analysis, and the results were used to establish dynamic soil reactions for single piles and pile groups for different types of sand and clay under harmonic loading with varying frequencies applied at the pile head. "Dynamic" p-multipliers were established to relate the dynamic load transfer curves of a pile in a group to the dynamic load transfer curves for a single pile. The dynamic p-multipliers were found to vary with the spacing between piles, soil type, peak amplitude of loading, and the angle between the line connecting any two piles and the direction of loading. The study indicated the effect of pile material and geometry, pile installation method, and pile head conditions on the p-multipliers. The calculated p-multipliers compared well with p-multipliers back-calculated from full scale field tests.Key words: lateral, transient loading, nonlinear, pile–soil–pile interaction, p–y curves, Statnamic.

Prediction of the horizontal load-displacement curves of pile groups based on the results of single pile tests

2000 ◽  
Vol 37 (5) ◽  
pp. 951-962 ◽  
Author(s):  
António GF de Sousa Coutinho
Keyword(s):  
Pile Group ◽  
Full Scale ◽  
Soil Parameters ◽  
Single Pile ◽  
Horizontal Load ◽  
Pile Groups ◽  
Nonlinear Method ◽  
Pile Test ◽  
Elastic Plastic ◽  
Load Displacement

This paper presents the prediction of horizontal load-displacement curves of pile groups based on the results of single pile tests. Although the same basic model is employed, two different approaches are taken: one assumes soil to be linear elastic-plastic, and the other assumes it to be elastic nonlinear. The model is calibrated on the basis of the results of a full-scale single pile test. Special emphasis is placed on model calibrations, since the success of any prediction method depends on a careful characterization of the soil. Some new approaches for determining the soil parameters are presented. Two methods for predicting load-displacement curves, one from each model approach, are then proposed and discussed. Special emphasis is placed on group efficiency in the elastic-plastic method and on the boundary conditions of the single pile and the pile group in the elastic nonlinear method. Using the soil characteristics from the model calibrations, the load-displacement curves for a given pile group are then predicted. These predictions are compared with the results of a full-scale pile group test carried out at the same site as that of the single pile test. Agreement between the predictions and the test results tends to validate the methods proposed.Key words: displacement predictions, pile groups, model calibration, pile tests.

Modeling of Piled Foundations

1982 ◽  
Vol 22 (05) ◽  
pp. 775-783
Author(s):  
Glenn A. Kriger
Keyword(s):  
Linear Models ◽  
Pile Group ◽  
Group Behavior ◽  
Model Construction ◽  
Single Pile ◽  
Pile Groups ◽  
Model Synthesis ◽  
Construction Methods ◽  
Single Piles ◽  
Piled Foundations

Abstract A comprehensive set of guidelines for constructing linear models of single piles and pile groups for foundations of offshore structures is presented. These models are used as boundary conditions at the base of the superstructure, thus permitting independent analysis of the superstructure from its supporting foundation.This paper is a "how-to" text for piled foundation modeling. It is also of value to those in related disciplines, such as geotechnical specialists, who will gain insight into how their data is applied in analyzing structures supported by piled foundations. Discussions include the behavior and modeling of single piles and pile groups. Construction methods are presented for pile groups. Construction methods are presented for three types of pile models-matrix, springs, and equivalent pile. The advantages and disadvantages of each model type are described. Linear and nonlinear foundation behavior characteristics are treated in depth. Factors that influence the approach to a modeling problem are outlined. Emphasis is placed on providing the problem are outlined. Emphasis is placed on providing the reader with an understanding of the physical behavior of piled foundations and model construction. A step-by-step piled foundations and model construction. A step-by-step procedure for model synthesis is provided in an example. procedure for model synthesis is provided in an example. Introduction In a fixed offshore platform, the steel jacket superstructure and its supporting piled foundation are more conveniently analyzed if treated separately. There are major structural and behavior-al differences between the jacket and foundation, and the two do not lend themselves to similar analytical methods. This paper presents basic techniques for constructing linear models that simulate the foundation behavior at the superstructure/foundation boundary. Use of these models permits independent superstructure analyses. Selection of the model type and its degree of refinement are described from a global overview of the structure, available data, and ramification of analytical results. Construction of the foundation simulation model follows routine procedures using results of an independent foundation analysis. Single Pile Behavior The load-deflection behavior of a single pile crown is of key importance in model construction. Analysis of a pile embedded in soil is extremely difficult because of pile embedded in soil is extremely difficult because of the infinite dimensions, nonhomogeneity, and nonlinearity of the soil. As a practical necessity, the problem usually is simplified by treating the pile as a beam-column supported by nonlinear axial and lateral soil springs. Details of these analytical procedures are beyond the scope of this work, although application of the techniques presented here will require the availability of such an analytical tool. Although this material pertains to single piles, it forms the basis for understanding pertains to single piles, it forms the basis for understanding pile group behavior discussed later. pile group behavior discussed later. Fig. 1 depicts a right-hand orthogonal coordinate system, which is used throughout this paper. Displacements, s, and forces, F, are shown in each of the six degrees of freedom (DOF). The pile behavior is studied by observation of the force(s) required to produce displacement in each of the six DOF while all other displacements are held at zero. Of utmost importance is the effect of coupling-the interaction of forces (and displacements) in different DOF.First consider linear pile behavior, which is characteristic of small-magnitude loadings. Force and displacement are directly proportional; therefore, stiffness (force divided by displacement) remains constant for all values of displacement (Fig. 2).Fig. 3a shows that an axial displacement is produced by an axial force. This axial displacement requires no other forces in each of the remaining five DOF. Therefore, linear axial pile behavior is uncoupled. Similarly, a torsional displacement (Fig. 3b) requires only a torque along the same DOF and therefore is also lineally uncoupled. SPEJ p. 775

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