ABSTRACT

A test programme was carried out in the small geotechnical centrifuge of the University of Delft to investigate the horizontal bearing capacity of suction piles in sand and clay. Thanks to the small size of the samples the soil density could be accurately reproduced, so that slight differences in design could be made visible. The influence of several parameters was tested, such as height/diameter ratio, the attachment point of the cable and loading angle. In some typical cases the failure mechanism was visualized in a three-dimensional test. The test results were compared with the API standard and with three-dimensional finite element calculations. It appeared that the optimum bearing capacity was achieved if the attachment point of the cable is at 2/5 of the pile height. The AP| calculations yield rather conservative values for the horizontal loads. The finite element calculations appeared to be in good agreement with the measured tendencies of the test results. It is believed that a combination of numerical calculations and tests in a small centrifuge yield a powerful design tool.

INTRODUCTION

In recent years, suction piles have been applied increasingly often in offshore engineering (Wang et al., 1978; Senpere et al., 1982). Suction piles are attractive because of the convenient method of installation. A pile with a diameter of 9 m and a height of 10 m can be installed in a few hours, by using a pump only. In a previous test programme (Allersma et al., 1997) the installation process was investigated by means of a centrifuge test. There was found to be a linear relationship between the pressure and parameters such as height, diameter and wall thickness. In this test programme the attention is focused on the static horizontal bearing capacity. In practice suction piles are used for several different loading conditions.

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