Abstract：Due to many merits such as high bearing capacity on bending and low cost, the large diameter concrete pile made with post-tension method is now widely used in harbour engineering：As the large pile is produced by dry-hard concrete through special procedures of high speed centrifugation, vibration and roll compaction, the lose of prestress for long time is different from conventional prestressed-concrete structures. By means of sensors embedded in the pile body, the research on its long-term prestress lose, caused by relaxtion of prestressed reinforcement and the shringage or creep of concrete, is carried out and its law has been obtained.
Abstract：Based on the field tests datas of six piles, the Q-S (load-displacement) curves of the new type of prestressed piles with rib were compared to the traditional smooth circular piles. And then according to the data measured by the standard penetration test (SPT) and cone penetration test (CPT) of the soil around the new type of piles, before or past the time of pile-construction, the soil squeezing efficiency was analysed. The results indicated that the load-displacement curves of the new type of prestressed piles with rib were expressed relatively even, and the ultimate bearing capacity of the new type of prestressed piles was increased 15% than that of smooth circular piles with equal diameter, obviously, the soil squeezing efficiency of the new type of piles was higher.