A semi-analytical solution for consolidation of soft ground improved by locally permeable pipe piles under time-dependent loads

Excessive pore-water pressure in soft soil can compromise pile bearing capacity, leading to foundation failure and posing a risk to structure stability. Hence expedited dissipation of excess pore-water pressure is critical. Permeable pipe piles offer an alternative to accelerating this consolidation process. In this study, a modified vertical equal-strain consolidation model of composite foundations with locally permeable pipe piles under arbitrary time-dependent loads is investigated. The integral transform and boundary transform methods are used to obtain a semi-analytical solution to this consolidation problem. The proposed solution's validity and correctness are further confirmed via theoretical degradation and numerical analysis. Subsequently, a sensitivity analysis in terms of opening parameters, pile-soil modulus ratio, soil's hydraulic conductivity ratio and pile's length-diameter ratio is conducted. The results indicate that the consolidation rate of the permeable pipe pile composite foundations demonstrates a significant enhancement over impermeable pipe pile composite foundations, especially for deep and soft foundations with high hydraulic conductivity ratios. The consolidation efficiency improves with the increase of pile's opening ratio, opening length and opening depth until it reaches a plateau at larger opening parameters. The research can provide theoretical support for design and construction of infrastructure with permeable pipe pile composite foundations.