Axial cyclic performance of a jacked pile in structured clays: A semi-analytical solution approach

Cyclic loads resulting from environmental factors such as wind, waves, trains, and construction activities pose a potential hazard to the stability of piled structures. These loads can cause the performance degradation of piles, including cumulative settlement and weakening of bearing capacity. This paper presents a semi-analytical solution for evaluating the axial cyclic behavior of jacked piles in structured clays. The solution employs enhanced nonlinear load-transfer models that effectively capture the stress-strain hysteresis and interfacial cyclic degradation characteristics. The key factors influencing pile behaviors are incorporated within the analytical approach, encompassing pile installation, subsequent soil equalization, and the static and cyclic loading encountered during service. The validity of the current solution is established through model pile tests conducted in artificially structured clays under static and cyclic loading conditions. Extensive parameter studies are performed using the proven theoretical approach to emphasize the influence of soil structure and cyclic loading on pile behavior. The results demonstrate a favorable agreement between the theoretical and measured values in static and cyclic pile response analyses. Compared with the response of jacked piles in reconstituted clays, the pile response in structured clays with a cement content of Aw = 4%, including penetration resistance, final ultimate bearing capacity, and the convergence speed of permanent settlement, has been substantially improved. The parameter studies indicate that soil structure and cyclic loading patterns significantly influence the axial cyclic performance of jacked piles in natural clays.