Abstract: The long piles of the ocean oil platform are usually manufactured as the integration of several segments which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even cause refusal. A drivability analysis method for judging the risk of refusal by estimating the blow counts after pile extension is proposed, penetration GRLWEAP software is used to calculate the subsequent piling hammer the required number of hammer, in which the regain of soil strength is considered via the fatigue factor β. A case study is made using the proposed method, so as to prove the feasibility and applicability of the method.

Key words: super long pile, refusal, excessive pore pressure, hydraulic fracture, drivability analysis method