Experimental Study on Post-Installed Axial Force Testing Technology for Pile Foundations

To address the challenges of in-situ axial force testing in pile foundations while ensuring sensor survivability, this study designed a post-installation axial force testing device and its testing technology. Finite element analysis and model tests were conducted to validate the proposed system. Shear failure specimens of installation pipes and grout materials were fabricated to evaluate the interfacial bonding strength, confirming that the adhesion between the pipe and grout meets the requirements for axial force transmission. A model pile embedded with the post-installation axial force testing device was constructed, and axial compression tests combined with numerical simulations were performed to verify the synergistic strain behavior between the pile body and the testing system. Furthermore, finite element models of driven steel pipe piles and prestressed high-strength concrete (PHC) piles were established to investigate the influence of grout strength variation (C30 to C90) on axial force measurement accuracy.