Open-ended pipe piles (OEPPs) are widely used in offshore foundations, yet accurately predicting their driving responses remains challenging due to soil plug complexities. Existing pile driving analysis models inadequately characterize the effects of soil plug, potentially leading to driving problems such as hammer refusal, pile running, and structural damage. This paper proposes an effective soil plug (ESP) model for OEPP driving analysis. The ESP model considers the effective range of soil plug, which exerts internal resistance that increases exponentially with depth while the beyond of effective range contributes only mass inertia. It also accounts for the relative slippage at the pile-soil plug interface. A differential iterative method is developed to solve the ESP model. Subsequently, investigations including the model validation and parameter analysis are conducted. Model validations against existing models and field measurements confirms the reliability of the ESP model. Parameters sensitivity analysis reveals the importance of soil plug length and distribution type of internal resistance on the pile dynamic responses. In addition, if soil plug slippage occurs, the displacement peak of soil plug increases with depth rather than one-dimensional wave attenuation. Furthermore, contrary to previous assumptions of continuous slippage, the soil plug experiences a discontinuous jump-sliding mode under long-duration impact loading. These findings provide theoretical basis for OEPP driving simulation and interpretations of high-strain dynamic test.

Impact pile driving is widely employed in various environments. The soil surrounding driven piles undergoes large shear displacements and highly cyclic loads, leading to significant strength degradation. This paper introduces a novel soil reaction model with easily calibrated parameters to estimate the pile penetration performance under continuous impact driving, incorporating both cyclic degradation and base gap. Soil cumulative plastic displacement is utilized to quantity the degradation, enabling more accurate simulation of cyclic pile response. The model is integrated into the pile driving system and applied in multiple-blow analysis. Non-linear cumulative displacement-blow count curves are analyzed and the development of residual stress varies between the pile upper and lower sections. It is found that lower blow counts are required when cyclic degradation is considered, although the increased rebound effect may counterbalance this benefit. Comparative analyses for degradation constants further demonstrate that early-stage degradation has a more pronounced impact. Finally, the proposed model is also adopted to predict blow count in field practice, offering valuable insights for driveability analysis.

Permeable pipe piles accelerate the bearing capacity of the pile foundation by releasing the excess pore water pressure (EPWP) of the soil around the pile through appropriate openings in the pile body. This study couples the Material Point Method (MPM) and the Finite Element Method (FEM) to establish a full-process model of pile driving and consolidation of permeable piles, and proposes a continuous drainage boundary condition that can reflect the plugging effect of permeable holes. The correctness of the model and boundary conditions are verified by comparison with experiments, and then the effects of soil properties, opening characteristics, and boundary permeability on the accelerated consolidation effect of permeable piles are analyzed. The results show that: the permeable pile with a permeable area ratio greater than 50% and a local opening ratio greater than 5% can save more than 60% of the consolidation time compared to conventional piles; the proposed boundary conditions can accurately describe the permeability of the permeable hole under the influence of plugging; in addition, the calculation formulae for the accelerated consolidation effect of permeable piles and the variation of continuous drainage boundary interface parameters with permeable area ratio are given, which can provide references for engineering design.

Open-ended pre-stressed high-strength concrete (PHC) pipe piles are susceptible to progressive distortion and even failure in the vicinity of the pile toe during driving into stiff soil or rock strata. This paper presents an experimental investigation conducted as part of a power plant construction in Huainan, China. After 50 piles were driven in the initial phase, the toe of 9 piles were detected as damaged using the sonic echo testing method. In the second construction phase, four piles were instrumented with longitudinal and circumferential fiber optic cables, as well as discrete strain gauges. The recorded responses of pipe piles throughout their driving process are analyzed to reveal the causes of damages. The results show that a maximum circumferential tensile stress developed at a distance of 1/6 pile length above the pile toe, with its value three times greater than that in other cross-sections. This high circumferential stress results in transverse cracks and the failure of open-ended PHC piles and is believed to be related to the formation of soil plugs. The findings provide valuable insights into performance evaluation of driven open-ended PHC piles.

The pore-water pressure response during vibratory pile driving considerably affects the piling process and environment. With the applications of high-frequency technology in upgrading the vibratory hammer, the pore-water pressure variation under high-frequency driving conditions becomes more complicated. However, there is a lack of relevant detailed investigations. This paper conducts an in situ experiment with a comprehensive monitoring and measuring system to examine the pore-water pressure response in the complete process of high-frequency vibratory pile driving. The real-time variations of pore-water pressure at the pile-soil interface and surrounding soil are evaluated, respectively. Furthermore, the excess pore-water pressure distributions and evolutions are analyzed in-depth. Then, the mechanism analysis and affected zone range determination are performed based on the development of excess pore-water pressure. The analysis results indicate that vibratory pile driving with high frequency leads to an increase of excess pore-water pressure and consequently soil quasi-liquefaction at the pile-soil interface. The apparent accumulation of excess pore-water pressure concentrates in the local range of soil around the pile tip and decays rapidly in the radial direction. According to the field observations, the increase of the pore-water pressure in the surrounding soil is attributed to the frictional penetration of the pile tip and the frictional vibration of the pile shaft. Furthermore, the maximum radial radii of the fully and partially quasi-liquefied zones are approximately 2.9 and 3.6 times the pile diameter, respectively.

Piles are deep foundation elements that play a crucial role in supporting substantial structural loads, particularly in the construction of heavily loaded port structures and bridges. Pile driving involves the installation of piles into the shoreline and/or seabed. These piles can be composed of different materials, including wood, concrete, steel, or a combination thereof. This article aims to provide an overview of pile driving fundamentals, highlight the common issues faced during the pile driving process, and potential solutions to address these challenges. The typical problems encountered in the advancement of displacement piles on large-scale marine projects are considered to include overrunning of piles, driving piles out of alignment, failing to account for obstructions, unexpected soil conditions, pile damage, lateral movement in adjacent piles, pile handling, and pile driving analysis issues. During pile installation, it is not uncommon to observe substantial differences between the field measurements obtained using a pile dynamic analyzer (PDA) and the axial capacity predicted by a GRLWEAP analysis. These discrepancies often arise when incorrect parameters are employed in the analysis. It is crucial to meticulously evaluate factors such as pile type, axial capacity, and site conditions during the design phase. Additionally, this article underscores the utmost significance of conducting a thorough soil investigation, including an understanding of the site's geology and development history. If necessary, conducting an indicative test pile program also helps to ensure the success of pile foundation design and construction.