Statistical research on performance of prestressed concrete pipe piles

An attempt is made in this study to research the performance of prestressed concrete pipe piles based on 10,333 pile tests. Short and medium-length piles with slenderness ratios ranging from 10 to 90 are most widely used, and the optimal length is between the range of 10~50 m. For the same bearing stratum and diameter, the capacity of pile increases with increasing pile length until a limiting value is achieved. The average pile-top settlement is approximately in the range of 10 ~ 25 mm, and the rebound rates for piles with various lengths are similar. The results show that the diameter of Φ400 and Φ500 is most widely used, accounting for 33.8% and 46.1%, respectively, and the optimal length is between the range of 10 ~ 50 m. Under conditions of, when the bearing stratum is clay, the bearing capacity of pipe piles increases with an increase in length to diameter ratio; when sandy soil, the bearing capacity firstly increases and then decreases; when with the same length to diameter ratio, the bearing capacity increases in both cases, and the latter is higher than the former. There is a large discreteness in settlement of pile top, and the average value is normally about 10 ~ 25 mm, without significant relationship with the bearing stratum. The results of statistical research will be a reliable reference for pipe pile research, design and construction in soft soil area. The results are expected to improve the understanding of prestressed concrete pipe piles and facilitate the design process.