When it comes to the general design of laterally loaded piles in offshore environments, bedding resistance is usually modelled by the p‐y method recommended in the offshore guidelines (OGL). Several investigations presented in the literature indicate that the head displacements of large‐diameter monopiles are underestimated for extreme loads but overestimated for small operational loads. An extensive evaluation of the OGL method is presented here using three‐dimensional numerical simulations. The evaluation has shown that the OGL method is not applicable for the design of large‐diameter piles. Moreover, modified p‐y formulations presented in the literature accounting for the effect of the pile diameter are also not generally suitable for piles with arbitrary dimensions and load levels. Therefore, the derivation of a new p‐y approach is presented in detail. The new approach consists of “basic p‐y curves” that are valid for a pile of infinite length exhibiting a constant horizontal deflection. In an iterative scheme, these basic curves are adapted depending on the pile deflection line and the pile length to account for a more realistic bedding resistance along the pile shaft. A comprehensive parametric study with 250 pile‐soil systems reveals that the new p‐y approach is able to predict the horizontal loadbearing behaviour as well as the local pile‐soil interaction quite realistically.Ein neuer statischer p‐y‐Ansatz für Pfähle beliebiger Abmessungen in Sand. Für die Bemessung horizontal belasteter Offshore‐Pfähle wird der Bettungswiderstand üblicherweise durch die in den Offshore‐Richtlinien (OGL) empfohlene p‐y‐Methode ermittelt. Verschiedene Untersuchungen aus der Literatur zeigen, dass die Verformungen von Monopiles mit großen Durchmessern für Extremlasten durch die OGL‐Methode unterschätzt, für geringe Betriebslasten dagegen überschätzt werden. Der vorliegende Artikel beinhaltet eine umfassende Bewertung der p‐y‐Methode basierend auf dreidimensionalen numerischen Simulationen. Als Ergebnis ist festzustellen, dass die OGL‐Methode zur Bemessung von Pfählen großer Durchmesser nicht geeignet erscheint. Auch modifizierte p‐y‐Ansätze zur Berücksichtigung des Einflusses des Pfahldurchmessers sind nicht generell anwendbar für Pfähle beliebiger Abmessungen und Belastungen. Diesbezüglich soll die Ermittlung eines neuen p‐y‐Ansatzes dargestellt werden. Der neue Ansatz basiert auf sogenannten “p‐y‐Basiskurven”, welche Gültigkeit für einen unendlich langen Pfahl mit einer über die Länge konstanten horizontalen Verschiebung aufweisen. In einem iterativen Vorgehen werden diese Basiskurven zur Erreichung eines realistischen Verlaufs der Bettungswiderstände in Abhängigkeit der Pfahlbiegelinie und ‐länge angepasst. Eine umfassende Parameterstudie mit 250 Pfahl‐Bodensystemen zeigt, dass der neue p‐y‐Ansatz geeignet ist, sowohl das globale Tragverhalten als auch die lokalen Pfahl‐Boden‐Interaktionen realistisch zu prognostizieren.

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The p-y method according to the offshore guidelines is usually applied for the design of laterally loaded piles. However, a number of modified p-y approaches for piles in noncohesive soils were proposed in the recent years to account for the effect of the pile diameter. These approaches were developed for piles in homogeneous soil but are used in current engineering practice for piles in layered sand as well. Concerning this matter, this paper presents a comparative evaluation of the existing p-y approaches for piles in layered sand by means of three-dimensional numerical simulations. Two large-diameter piles in widely varied layered sand representing a monopile and a pile of a lattice structure for the foundation of an offshore wind energy converter are considered. It is demonstrated that the effect of the layering is limited; that is, the deviations of the analytical results from the numerical results are predominantly associated with the deviations obtained for homogeneous sand. An occasionally used overlay procedure to adapt the p-y curves depending on the adjacent soil layers is shown to have not only a small impact on the analytical results but also some major deficiencies with regard to a reliable consideration of the layering.

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A Monte Carlo simulation code is described that is suitable for modelling low-pressure glow discharges that possess cylindricaLsymmetry, but are of otherwise completely variable geometry. In this single-particle simulation in 3 space and 3 velocity dimensions, an entire discharge including the cathode fall can be modelled with or without magnetic fields of arbitrary shape. Electric and magnetic fields are given externally and are not adjusted self-consistently. Collision processes are modelled in great detail, and cathode sputtering phenomena are also included in the simulation.This simulation code is applied to hollow cathode discharges with and without superimposed magnetic fields and to a Penning discharge. Exemplary results are shown that include density profiles of cathodesputtered atoms, energy distribution functions of electrons and cathode sputtering effects for a Penning discharge. Comparisons to results from experiment and other simulations are given.