Comparative study on bearing capacity of enhanced pretensioned spun concrete piles and conventional pipe piles

The application of the traditional pretensioned spun concrete pile (TPSCP) is limited in soft soils for its lower shaft resistance, backward connection method, weak bending-resistance and tensile properties. The enhanced pretensioned spun concrete pile (EPSCP) is developed on the basis of TPSCP, and its conformation, construction technology and a set of mechanical bonding joints are introduced. According to the static load tests, the results are as follows: (1) the vertical allowable load capacity of single EPSCP can be 1.23 times as much as that of TPSCP under the same pile diameter and pile length; (2) Compared with that of the TPSCP with the same diameter and length, the vertical ultimate uplift resistance of single EPSCP is increased by 73.3%. It is shown that the shaft resistance of the EPSCP can be improved by setting the ring and longitudinal rib along the pile shaft, and its compressive and tensile characters are ameliorated. So the application of the EPSCP can be extended for its better economic efficiency and social benefits with broad prospects.