Time-Dependent Analysis of Bearing Capacity for Permeable Pipe Piles with Localized Openings in Layered Soft Clay

This study develops a theoretical model for predicting the time-dependent bearing capacity of permeable pipe piles in deep layered soft soils, utilizing a consolidation-degree-dependent load-transfer method. It reveals the mechanism of side friction mobilization and the evolution of negative skin friction in precast piles embedded in soft soil. Firstly, an analytical solution for foundation consolidation considering pile side drainage is derived based on the three-dimensional axisymmetric consolidation theory, which is then combined with a nonlinear time-varying load transfer function to simulate the time-varying pile-soil interaction. The validity of the proposed theoretical model was verified through comparisons with existing model tests and field measurement data. Finally, a parametric sensitivity analysis was conducted on the opening rate, opening position and opening length of the permeable pipe pile. The study reveals that the opening rate of the permeable pipe pile is the primary factor affecting the consolidation of the foundation and the efficiency of the bearing capacity. With the increase of the opening rate, the drainage effect is enhanced, but when the opening rate exceeds 2.0‰ ~ 2.5 ‰, the marginal benefit diminishes. Furthermore, reasonable local opening design (such as covering the neutral point to the pile tip) can achieve the drainage effect close to the full pile long opening while ensuring the structural strength of the pile.