مدل سازی عددی توسط عناصر متناهی در یک پی شمعی تحت اقدامات چرخه ای جانبی Numerical modelling by finite elements for a pile foundation under lateral cyclic action

1 INTRODUCTION Off-shore structures, as for example oil platforms or off-shore wind mills, coastal structures or harbours, but also terrestrial structures are often submitted to cyclic lateral forces given by wind, waves, mooring forces or earthquakes. Such structures are usually built on pile foundations due to high forces to be transferred to the ground and also to the fact that usually are founded on grounds with soft, alluvial layers near surface. The strong aleatory character of cyclic actions, which can also have an important dynamic component, is giving a high complexity to their approach. For this reason, the variable actions are often consider as equivalent to a static one (the pseudo-static method) and the cyclic parameters are ignored, which can lead sometimes to an unconservative design. Also, complex soil – structure interaction phenomena appearing are difficult to model. For a better understanding of the behaviour of piles under lateral cyclic actions experimental models are needed. On international level the use of small-scale models tested in centrifuge is one of the best choices for analysing such foundations. Based on the experimental results, one can develop and calibrate numerical models to be used in design practice. The objective of this paper is to develop a numerical model calibrated based on experimental centrifuge results. Those latest have been obtained from IFSTTAR Nantes (France), being carried out by Rosquoët between 2002-2004 (Rosquoët 2004). The centrifuge tests were performed on a single pile in dry sand submitted to cyclic loading. Rosquoët (Rosquoët 2004) realized a couple of dozen tests, in which he varied four determinant parameters:  Unit weight of the sandy soil (15.1; 16; 16.5 kN/m3 );  Force applied on the pile’s head (300; 450; 600 N);  Amplitude of loading (150; 300; 450; 600 N);  Number of cycles (from 12 to 44).