Analysis and Comparison of In-situ Full Scale Test of Pile-head Core Pullout Resistance of Improved PHC Pile

PHC pile is the most widely used pile in mainland China and Taiwan, and the joint between pile head and pile cap is a problem that cannot be solved effectively in foundation engineering. Pullout resistance force on the pile-head core of improved PHC pile is tested in full scale, and the test result is compared with theoretical calculation and conventional estimation of PHC pile. The test pile of PHC 600 B 100-10 is a 600 mm diameter, 10 m long pile with pile head of 2 m in length. There are 6 layers in 2 by 2 horizontal D19 rebars placed within inner portion of the pile head. Test is followed with ASTM-D3689M. The result shows that the pullout loading goes up to 175 tons, and the theoretical value of the pullout resistance force calculated from the pile-head core is 371 tons, which is 7.5 times and 6.2 times higher of the pullout resistance force of the 2 m long pile-head core compared to the conventional PHC pile proposed by two literature studies respectively. The result also shows that the improved PHC pile can be more effectively connected with the pile cap.