Experimental Research on Mechanical Properties of PHC Pipe Pile Filled with Core Concrete Under Axial Tension

In order to popularize PHC uplift pipe pile in UHV transmission line pile foundation, the uplift bearing performance of the bonding surface between core concrete and the inner wall of pipe pile was investigated. The full-scale tests of 6 PHC 600 B 130 uplift piles were completed. In the test, different core filling lengths and interface treatment methods of the inner wall of the pipe pile were considered, the test results of axial tension, average bond strength of the interface, bond coefficients of the interface, and slip were obtained. The results showed that the maximum axial tensile force of each specimen increased linearly with the increase of core length. The average bond strength test value of the whole length of the core filled concrete interface was between 0.603 MPa and 0.774 MPa, and the core filling length and interface treatment method had little influence on the test results. Along the whole length of the pipe pile core filling, the bond strength and slip of the core filling concrete interface on each section were larger near the loading end while smaller away from the loading end. The core filling concrete near the loading end bears a larger proportion of axial tensile load. The design value of the average bond strength of the whole length of the core concrete interface could be taken as 0.30 MPa.