Soil‐pile interaction in vertical vibration induced through a frictional interface

Akiyoshi, T.

doi:10.1002/eqe.4290100110

Cited by 24 publications

(16 citation statements)

References 7 publications

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“…Soil is assumed to be a linear viscoelastic material of Young's modulus , Poisson's ratio mass density and linear hysteretic damping expressed through the complex shear modulus . Unlike most previous studies, (e.g., Nogami & Novak, 1976;Akiyoshi, 1982), the pile is modelled as a continuum, without the limitations associated with strength-of-materials approximations. The pile is described by its diameter d, Young's modulus , Poisson's ratio and mass density .…”

Section: Problem Definition and Model Developmentmentioning

confidence: 99%

“…Purely analytical studies are based primarily on two-dimensional idealizations for wave propagation in the soil, associated with the approximate model of Baranov and Novak (Baranov, 1967;Novak, 1974;Novak et al, 1978;Veletsos & Dotson, 1986;Mylonakis, 1995;El Naggar, 2000). On the other hand, analytical solutions based on three-dimensional wave propagation theory, which can provide more realistic predictions and shed light into fundamental aspects of dynamic pile-soil interaction, have been explored to a lesser degree (Tajimi, 1969;Nogami & Novak, 1976;Akiyoshi, 1982;Mylonakis, 2001b;Saitoh, 2005;Anoyatis, 2009). …”

Section: Introductionmentioning

confidence: 99%

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Dynamic Winkler modulus for axially loaded piles

Anoyatis¹,

Mylonakis²

2012

Géotechnique

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The problem of axial dynamic pile–soil interaction and its analytical representation using the concept of a dynamic Winkler support are revisited. It is shown that depth- and frequency-dependent Winkler springs and dashpots, obtained by dividing the complex-valued side friction and the corresponding displacements along the pile, may faithfully describe the interaction effect, contrary to the common perception that the Winkler concept is always approximate. An axisymmetric wave solution, based on linear elastodynamic theory, is then derived for the harmonic steady-state response of finite and infinitely long piles in a homogeneous viscoelastic soil stratum, with the former type of pile resting on rigid rock. The pile is modelled as a continuum, without the restrictions associated with strength-of-materials approximations. Closed-form solutions are obtained for: (a) the displacement field in the soil and the pile; (b) the stiffness and damping (‘impedance') coefficients at the pile head; (c) the actual, depth-dependent, dynamic Winkler moduli; and (d) a set of fictitious, depth-independent Winkler moduli to match the dynamic response at the pile head. Results are presented in terms of dimensionless graphs, tables and simple equations that provide insight into the complex physics of the problem. The predictions of the model compare favourably with existing solutions, while new results and simple design-oriented formulae are presented.

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Section: Problem Definition and Model Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamic Winkler modulus for axially loaded piles

Anoyatis¹,

Mylonakis²

2012

Géotechnique

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“…Indeed, most relevant analytical models are restricted to two dimensions and, therefore, cannot capture key aspects of the problem such as continuity of the medium in the vertical direction and attenuation of settlement with radial distance from the pile. On the other hand, three‐dimensional analytical models that can provide more realistic predictions over two‐dimensional counterparts have been explored to a lesser degree …”

Section: Introductionmentioning

confidence: 99%

“…the other hand, three-dimensional analytical models that can provide more realistic predictions over two-dimensional counterparts have been explored to a lesser degree. [33][34][35][36][37] A promising family of three-dimensional analytical models is the one associated with the approximate continuum formulations of Matsuo and Ohara 38 and Tajimi, 39 which, in turn, have their roots in the classical point-load solution of Westergaard. 40 These models (often referred to as Tajimi formulations) reduce the number of dependent variables by eliminating certain stress and displacement components in the governing equations and express the solution in terms of eigenfunctions along the vertical coordinate.…”

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confidence: 99%

An analytical continuum model for axially loaded end‐bearing piles in inhomogeneous soil

Anoyatis

Mylonakis

Tsikas³

2019

Num Anal Meth Geomechanics

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Summary An approximate static solution is derived for the elastic settlement and load‐transfer mechanism in axially loaded end‐bearing piles in inhomogeneous soil obeying a power law variation in shear modulus with depth. The proposed generalised formulation can handle different types of soil inhomogeneity by employing pertinent eigenexpansions of the dependent variables over the vertical coordinate, in the form of static soil “modes”, analogous to those used in structural dynamics. Contrary to available models for homogeneous soil, the associated Fourier coefficients are coupled, obtained as solutions to a set of simultaneous algebraic equations of equal rank to the number of modes considered. Closed‐form solutions are derived for the (1) pile head stiffness; (2) pile settlement, axial stress, and side friction profiles leading to actual, depth‐dependent Winkler moduli, (3) displacement and stress fields in the soil; and (4) average, depth‐independent Winkler moduli to match pile head settlement. The predictive power of the model is verified via comparisons against finite element analyses. The applicability to inhomogeneous soil of an existing regression formula for the average Winkler modulus is explored.

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“…Summaries of available information are provided in Tajimi [17], Pender [18], Gazetas and Mylonakis [19], Syngros [20], Guo [21] and more recently by Saitoh and Watanabe [5] and Shadlou and Bhattacharya [22]. Additional information on the Tajimi model is provided by Akiyoshi [23], Veletsos and Younan [6], Chau and Yang [24], Latini et al [25], Mylonakis [36], Anoyatis and Mylonakis [27] and Novak and Nogami [37].…”

Section: Introductionmentioning

confidence: 99%

Dynamic pile impedances for laterally–loaded piles using improved Tajimi and Winkler formulations

Anoyatis

Lemnitzer

2017

Soil Dynamics and Earthquake Engineering

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a b s t r a c tThe analytical representation of dynamic soil reaction to a laterally-loaded pile using 3D continuum modeling is revisited. The governing elastodynamic Navier equations are simplified by setting the dynamic vertical normal stresses in the soil equal to zero, which uncouples the equilibrium in vertical and horizontal directions and allows a closed-form solution to be obtained. This physically motivated approximation, correctly conforming to the existence of a free surface, was not exploited in earlier studies by Tajimi, Nogami and Novak and leads to a weaker dependence of soil response to Poisson's ratio which is in agreement with numerical solutions found in literature. The stress and displacement fields in the soil and the associated reaction to an arbitrary harmonic pile displacement are derived analytically using pertinent displacement potentials and eigenvalue expansions over the vertical coordinate. Both infinitely long piles and piles of finite length are considered. Results are presented in terms of dimensionless parameters and graphs that highlight salient aspects of the problem. A detailed discussion on wave propagation and cutoff frequencies based on the analytical findings is provided. A new dimensionless frequency parameter is introduced to demonstrate that the popular plane-strain model yields realistic values for soil reaction only at high frequencies and low Poisson's ratios.Published by Elsevier Ltd.

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Soil‐pile interaction in vertical vibration induced through a frictional interface

Cited by 24 publications

References 7 publications

Dynamic Winkler modulus for axially loaded piles

Dynamic Winkler modulus for axially loaded piles

An analytical continuum model for axially loaded end‐bearing piles in inhomogeneous soil

Dynamic pile impedances for laterally–loaded piles using improved Tajimi and Winkler formulations

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