Power transfer and vibrator-pile-soil interactions within the framework of vibratory pile driving

The vibratory driving technique is used for driving piles and sheet piles into the ground, by imparting to the profile a longitudinal vibratory motion. Performance of the technique results from interactions between the driving unit, the pile and the soil. The objective of the present thesis is to develop a better understanding of those interactions. The research is based on a detailed study of experimental results, consisting in full scale vibratory driving tests and experience databases. A large amount of data was available thanks to the partners (and other participating organizations) of this research (BBRI, Arcelor-Mittal, Deltares, LCPC). A new full scale test campaign was also conducted in Limelette (Belgium) for investigating specific questions such as the influence of vibratory parameters and sheet pile movements on the efficiency of the technique, in terms of both driving time and power consumption. Analysis of the experimental results has allowed some shortcomings in the current methods addressing pile vibrodrivability to be identified. Shortcomings are mainly related to the assumptions regarding the vibratory action actually applied to the pile (force and frequency), the (sheet) pile movement, and the definition of soil parameters. The second part of the thesis is devoted to the improvement of vibrodriving prediction methods based on theoretical and experimental conclusions. In particular, suggestions are made to correct the definition of the vibratory force and to account for the possible influence of power limitation coming from the power pack. In that process, the definitions of the soil parameters are revisited based on the literature and experimental studies. Also the possibility of extending vibrodriving models for the prediction of power consumption is investigated, as well as the possibility to override the rigid body assumption through use of the finite element approach.Le vibrofonçage est utilisé pour foncer des pieux et palplanches dans le sol, en imposant au profil à foncer un mouvement vibratoire longitudinal. Les performances de cette technique résultent des interactions entre l’équipement de vibrofonçage, le pieu et le sol. L’objectif de la présente recherche est de développer une meilleure compréhension de ces interactions. La recherche se base sur une étude détaillée de résultats expérimentaux, issus d’essais de vibrofonçage en vraie grandeur et de bases de données constituées de relevés d’expériences. Une grande quantité de données était disponible grâce aux partenaires de la recherche, et autres organismes participant (BBRI, Arcelor-Mittal, Deltares, LCPC). Une nouvelle campagne d’essais en vraie grandeur a également été menée à Limelette (Belgique) pour investiguer des questions plus spécifiques telles que l’influence des paramètres de vibrofonçage et l’influence des mouvements de la palplanche sur l’efficacité de la technique, en termes de vitesse de fonçage et consommation énergétique. L’analyse de ces résultats expérimentaux a permis d’identifier des lacunes dans les méthodes actuelles de prédiction du vibrofonçage. Ces lacunes sont principalement liées aux hypothèses concernant l’action du vibrateur sur le pieu (force et fréquence), le comportement du pieu (ou de la palplanche), et la définition des paramètres de sol. La seconde partie de la thèse est consacrée à l’amélioration des méthodes de prédiction du vibrofonçage sur base des conclusions des études théoriques et expérimentales. En particulier, des suggestions sont faites pour corriger l’expression de la force vibratoire et prendre en compte l’effet d’un possible manque de puissance du groupe hydraulique, tandis que la définition des paramètres de sol est revue sur base de l’étude de littérature et des résultats expérimentaux. La possibilité d’étendre les modèles de calcul à la prédiction de la consommation énergétique lors du vibrofonçage est finalement étudiée, de même que la possibilité de s’écarter de l’hypothèse du corps rigide pour représenter le pieu, grâce à une approche par éléments finis.(FSA 3) -- UCL, 201

Axial Non-linear Dynamic Soil-Pile Interaction

This chapter describes recent analytical and numerical advances in the modeling of the axial nonlinear dynamic interaction between a single pile and its embedding soil. On one hand, analytical solutions are developed for assessing the nonlinear axial dynamic response of the shaft of a pile subjected to dynamic loads, and in particular to vibratory loads. Radial inhomogeneity arising from shear modulus degradation is evaluated over a range of parameters and compared with those obtained by other authors and by a numerical radial discrete model simulating the pile and soil movements from integration of the laws of motion. New approximate non linear solutions for axial pile shaft behaviour developed from general elastodynamic equations are presented and compared to existing linear solutions. The soil non linear behaviour and its ability to dissipate mechanical energy upon cyclic loading are shown to have a significant influence on the mechanical impedance provided by the surrounding soil against pile shaft movement. The limitations of over-simplified modelling of pile response are highlighted

Critical Review of the Hypervib1 Model to Assess Pile Vibro-Drivability

The vibratory driving technique is used for driving piles, sheet piles, tubes and rods into the ground by imparting to the element a longitudinal periodic motion. The small amplitude vibrations induced by the equipment reduce the ground resistance which allows penetration under the action of a relatively small axial force. The technique offers an alternative to impact driving due to lower installation costs and reduced environmental disturbance (noise, vibration, etc.) especially in sensitive environments, such as industrial and urban sites or offshore wind farm sites. The vibratory technique is also preferred when the maximum stress levels imparted to the driven element are of concern. Despite the advantages of the vibratory driving technique, its application remains however mainly driven by pragmatic aspects. Within that context, the access to experience databases and full-scale field test results is of valuable interest. The aim of this paper is to review the Hypervib1 model developed by (Holeyman 1993) for assessing the vibratory drivability of piles and sheet piles, based on the analysis of such experimental results. New findings and developments brought to the model are discussed. Conclusions in terms of reliability of the method are finally drawn

Vibrodriving prediction models vs. experimental results

This paper reviews and discusses methods currently available to assess the vibro-driveability of piles based on a comparison between calculations and experimental observations. The experimental results come from databases collected in Belgium and in The Netherlands, as well as from full scale tests campaigns conducted in Belgium and in France. Discrepancies between modeling assumptions and actual observations are highlighted, and some suggestions are made to improve the performance of design methods

Intrillen van damplanken: Invloed parameters en voorspellingsmethodes

Dit artikel focust op de interacties tussen de trilmachnes, de damplank en de grond

Impedance of pile shafts under axial vibratory loads

This paper describes analytical solutions for assessing the axial dynamic response of the shaft of a pile subjected to vibratory loads, with particular reference to pile vibratory driving. Radial inhomogeneity arising from shear modulus degradation is accounted for by assuming continuous variations of the medium properties. This approach alleviates wave reflections from the interface between inner (nonlinear) and outer (linear) zones. Novel analytical solutions are presented for two cases describing the radial decrease of the soil modulus according to (a) a linear law and (b) a parabolic law. The results are evaluated over a wide range of parameters and compared with those obtained by a semi-analytical model derived from Michaelides et al. [14,15] and by a radial discrete model simulating the pile and soil movements from integration of the laws of motion (Hipervib-II model) (Holeyman [8]). © 2012 Elsevier Ltd

Racisme et luttes de classes. Essai d'analyse sociologique de discours d'enfants sur le racisme, l'étranger et les sentiements d'appartenance ethnique

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