THE FORMATION MECHANISM OF SUPER LARGE DIAMETER AND DEEP PENETRATION PILE IN OFFSHORE PLATFORM

With the platform size increase, the super large diameter and deep penetration pipe piles are increasingly used in practice. Pile driving maybe suspended because of many reasons during installation. Whether the driving could re-strike or not is an important problem that many people concerned，and it is related to pile capacity set-up. Based on a case study, the characteristics of the soil in this area are summarized, and the influence of end bearing and skin friction on pile driving are analyze. At the same time, the soil resistance is calculated and the change of soil resistance with time is discussed according to driving record and in situ tests. It is found that the soil properties play a very important role in pile driving. For the super large diameter and deep penetration pipe pile, the soil in the pile is not plugged completely, and the average ratio of skin friction in continuous driving to static skin friction is 0.68. The soil resistance increases about 65% after a driving suspension of about 6 weeks. After 3 months driving suspended, the soil resistance is greater than the static bearing capacity, and the increment of pile bearing capacity with time is very obvious.