%0 Journal Article
%T R¨¦paration des pieux battus dans les sables carbonat¨¦s Repair of Driven Piles in Calcareous Formations
%A Nauroy J. F.
%A Brucy F.
%A Le Tirant P.
%A Barthelemy H.
%J Oil & Gas Science and Technology
%D 2006
%I Institut Fran?ais du P¨¦trole
%R 10.2516/ogst:1988032
%X Les formations carbonat¨¦es rencontr¨¦es en de nombreuses zones d'activit¨¦s p¨¦troli¨¨res en mer posent de difficiles probl¨¨mes de dimensionnement et de mise en place des pieux. Sur plusieurs sites de sable carbonat¨¦, la capacit¨¦ portante des pieux battus se r¨¦v¨¨le beaucoup plus faible que pr¨¦vu et des techniques de r¨¦paration doivent ¨ºtre ¨¦tudi¨¦es. Dans ce contexte, l'ARGEMA (Association de Recherche en G¨¦otechnique Marine), groupement fran ais d'organismes de recherche, de compagnies p¨¦troli¨¨res et de contracteurs offshore, a exp¨¦riment¨¦ une r¨¦paration d'un pieu exp¨¦rimental de 30 cm de diam¨¨tre et 23 m de long battu dans un sable carbonat¨¦. Le frottement lat¨¦ral de ce pieu mobilis¨¦ juste apr¨¨s battage ¨¦tait tr¨¨s faible. La r¨¦paration a consist¨¦ ¨¤ injecter du coulis de ciment ¨¤ partir d'un forage situ¨¦ ¨¤ 40 cm du pieu. Cet article d¨¦crit les proc¨¦dures et les caract¨¦ristiques des injections r¨¦alis¨¦es et leurs cons¨¦quences sur la capacit¨¦ portante du pieu. Le frottement entre le pieu et le terrain s'accro t avec le volume de ciment inject¨¦; les valeurs maximales obtenues sont du m¨ºme ordre de grandeur que celles observ¨¦es avec un pieu for¨¦-ciment¨¦. The calcareous formations encountered in many zones of offshore petroleum activity raise difficult problems for designing and installing foundation piles. On several sites with calcareous sands, the bearing capacity of driven piles proves to be much less than had been planned, and repair techniques have to be examined. Within this context, ARGEMA (Association de Recherche en G¨¦otechnique Marine), a french group of research organizations, oil companies and offshore contractors, has tested a repair of an experimental pile 30 cm in diameter and 23 m long driven into a calcareous sand. The skin friction of this pile, mobilized just after driving, was found to be very low. The repair-job consisted in injecting grout from a drilled borehole located at some tens of centimeters outside the pile. The paper describes the procedures and the characteristics of grout injections and their results on the pile bearing capacity. The skin friction mobilized between the pile and the soil depends to a great degree on the volume of grout injected, a small part of which appears to reach the pile; the maximum values are of the same order of amplitude as that obtained, with a drilled and grouted pile in the same formation.
%U http://dx.doi.org/10.2516/ogst:1988032