Single Piles and Pile Groups Under Lateral Loading

Reese, Lymon C.; Impe, W. Van; Holtz, Robert D.

doi:10.1115/1.1445326

Cited by 104 publications

(97 citation statements)

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“…Research has included testing of full-sized piles in sand under both static and cyclic loading conditions. An overview of the important tests and results is given by Reese & Impe (2001). The p-y curves for piles in sand described by Reese et al (1974) and O'Neill & Murchison (1983) led to recommendations in the standards (DNV, 1977;API, 1993) for oil and gas installations.…”

Section: Current Methodsologymentioning

confidence: 99%

Response of stiff piles in sand to long-term cyclic lateral loading

LeBlanc¹,

Houlsby²,

Byrne³

2010

Géotechnique

490

273

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The driven monopile is currently the preferred foundation type for most offshore wind farms. While the static capacity of the monopile is important, a safe design must also address issues of accumulated rotation and changes in stiffness after long-term cyclic loading. Design guidance on this issue is limited. To address this, a series of laboratory tests were conducted where a stiff pile in drained sand was subjected to between 8000 and 60 000 cycles of combined moment and horizontal loading. A typical design for an offshore wind turbine monopile was used as a basis for the study, to ensure that pile dimensions and loading ranges were realistic. A complete non-dimensional framework for stiff piles in sand is presented, and applied to interpret the test results. The accumulated rotation was found to be dependent on relative density, and was strongly affected by the characteristics of the applied cyclic load. Particular loading characteristics were found to cause a significant increase in the accumulated rotation. The pile stiffness increased with number of cycles, which contrasts with the current methodology where static load-displacement curves are degraded to account for cyclic loading. Methods are presented to predict the change in stiffness and the accumulated rotation of a stiff pile due to long-term cyclic loading. The use of the methods developed is demonstrated for a typical fullscale monopile.KEYWORDS: laboratory tests; piles; repeated loading; sands; settlement; stiffness Le monopieu battu est actuellement le type de fondation préféré pour la plupart des parcs éoliens en mer. Bien que la capacité statique du monopieu soit importante, une conception sans danger doit également tenir compte des problèmes de la rotation accumulée et de variations dans la rigidité, à la suite d'efforts cycliques de longue durée. Les conseils et indications conceptuels relatifs à cette question étant limités, on a procédé à une série d'essais en laboratoire, dans le cadre desquels on a soumis un pieu rigide, enfoncé dans du sable drainé, à un nombre de cycles de moment de charge et de charges horizontales allant de 8000 à 60 000. On a utilisé, comme élément de base de cette étude, un modèle typique de monopieu pour éolienne en mer, afin d'assurer que les dimensions du pieu et les plages de charge étaient réalistes. Pour interpréter les résultats de cet essai, on présente et on applique un cadre non dimensionnel complet pour pieux rigides dans le sable. La rotation cumulée, qui s'est avérée tributaire du poids spécifique, était affectée dans une grande mesure par les caractéris-tiques de la charge cyclique appliquée. On s'est aperçu que certaines caractéristiques particulières de la charge engendraient une augmentaiton significative de la rotation cumulée. La rigidité du pieu augmentait avec le nombre de cycles, contrairement à la méthodologie actuelle, dans laquelle les courbes charge statique/déplace-ment sont dégradées pour tenir compte des charges cycliques. La communication présente des méthodes permettant de prédire les ...

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Section: Current Methodsologymentioning

confidence: 99%

Response of stiff piles in sand to long-term cyclic lateral loading

LeBlanc¹,

Houlsby²,

Byrne³

2010

Géotechnique

490

273

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“…Piles subjected to lateral forces and moments at the head are analysed in practice with the p-y method (Reese & Cox, 1969;Matlock, 1970;Reese et al, 1974Reese et al, , 1975Reese & Van Impe, 2001). In the p-y method the pile is assumed to behave as an Euler-Bernoulli beam with the soil modelled as a series of discretely spaced springs, each connected to one of the pile segments into which the pile is discretised.…”

Section: Introductionmentioning

confidence: 99%

A continuum-based model for analysis of laterally loaded piles in layered soils

2009

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An analysis is developed to calculate the response of laterally loaded piles in multilayered elastic media. The displacement fields in the analysis are taken to be the products of independent functions that vary in the vertical, radial and circumferential directions. The governing differential equations for the pile deflections in different soil layers are obtained using the principle of minimum potential energy. Solutions for pile deflection are obtained analytically, whereas those for soil displacements are obtained using the one-dimensional finite difference method. The input parameters needed for the analysis are the pile geometry, the soil profile, and the elastic constants of the soil and pile. The method produces results with accuracy comparable with that of a three-dimensional finite element analysis but requires much less computation time. The analysis can be extended to account for soil non-linearity.

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“…The interaction of the piles in the group increases resulting deformations and reduces the overall capacities of the Fig. 15 Circles of questions for site investigation [51] group to less than the aggregate sum of individual piles [65,67].…”

Section: Scale Effectmentioning

confidence: 99%

The first William Selim Hanna honor lecture from failure to success: lessons from geotechnical failures

Agaiby

Salem

Ahmed

2017

Innov. Infrastruct. Solut.

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An engineering failure may be defined as an unforeseen, substandard, performance of an engineered element. It can materialize in the forms of a catastrophic incident or just as a slight functional shortcoming. Failures are not all evil despite our natural aversion to encounter them. In fact, they are both our greatest enemy and, ironically, our foremost educator. Our ancestors who worked as ''geotechnical engineers'' based their design on experiences gained from failures. This is still the case until now despite the technological advances made by humankind especially in engineering. Unfortunate incidents of failures still happen and they coach us on how to design our buildings. Structures continuously tend to become heavier, bigger, and taller. Indeed, the odds of failures increase as we cross the limits of our engineering knowledge every day. Experts commonly disagree about the nature of failures due to their extreme complexities. Comprehending the causes of failures is one of the most difficult tasks for engineers. A special branch of integrated engineering studies that comprises sophisticated analyses has been established to study failures; Forensic Engineering. In this paper, different aspects of geotechnical failures, including their common causes, are highlighted. Some well-documented geotechnical failures are briefly described and lessons learnt from these failures are revisited with an emphasis on prevention measures of possible failures.

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Single Piles and Pile Groups Under Lateral Loading

Cited by 104 publications

References 0 publications

Response of stiff piles in sand to long-term cyclic lateral loading

Response of stiff piles in sand to long-term cyclic lateral loading

A continuum-based model for analysis of laterally loaded piles in layered soils

The first William Selim Hanna honor lecture from failure to success: lessons from geotechnical failures

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