Experimental–Numerical Analysis of the Ultimate Lateral Capacity of PHC Piles

A Theoretical Framework for Predicting Soil Setup in Laterally Loaded Piles in Clay

Soil setup is known to enhance the capacity of jacked piles and is well documented for axial resistance, but its influence on lateral behavior and corresponding evaluation methods remain limited. In this study, a new theoretical framework is proposed to estimate the time-dependent lateral response of closed-ended piles in normally consolidated clay by jointly considering installation-induced disturbance and subsequent consolidation. The framework couples cavity expansion theory with an effective stress approach to capture the evolution of pore pressure, effective stress and strength from installation through reconsolidation, and to quantify the attendant changes in pile–soil interaction. Its performance is demonstrated against finite-element simulations and a field experiment, showing close agreement. Results reveal a strong link between lateral capacity gain and the dissipation of excess pore pressure. Parametric studies further show that rigid piles experience significantly greater capacity improvements than flexible piles, as their associated soil flow mechanisms enable the mobilization of a wider zone of strength-enhanced soil. In addition, increasing pile diameter prolongs the dissipation of excess pore pressure and thus the setup process. While the setup effect for laterally loaded piles is generally less substantial than that widely reported for axially loaded piles, especially for flexible piles, the present framework offers a useful means of evaluating its influence in applications where lateral stiffness and deformation are particularly sensitive and govern performance.

Numerical Investigation of the Lateral Loading Behaviour of Plate–Monopile Hybrid Foundations in Clay

Plate–monopile hybrid foundations, as a potential alternative to monopiles, have demonstrated promising potential in enhancing load-bearing capacity and structural stability. To investigate its load transfer mechanisms and pile–soil interaction in clay, numerical models are developed under varying undrained shear strength (Su), pile diameter (D), and plate-to-pile diameter ratio (R). Through comparative analyses within different parameters configurations, the load-bearing capacity, pile deflection, bending moment and shear force distributions are systematically examined. The results indicate that: (1) Su, D and R are all positively correlated with the load-bearing capacity of the hybrid foundation, which can be expressed as the superposition of the monopile capacity and a quadratic function of R; (2) with increasing R, load transfer shifts from deep to shallow soil, accompanied by an upward pivot shift; increasing D causes a downward shift, more pronounced in weak soils; (3) for small-diameter hybrid foundation, the bending moment decreases progressively with increasing R, while for large-diameter, a stage-dependent response is observed, characterised by local moment concentration near the mudline within a certain range of R; (4) the shear force exhibits a double-peak pattern; increasing R strengthens the shallow peak and weakens the deep one, while increasing D localises the distribution near the mudline.

Simulation and measurement of pile settlement: a comparative study of pressure metric and numerical approaches

A Simplified Method for Calculating the Lateral Bearing Capacity of Rectangular Piles in Sloping Ground

Evaluating the lateral bearing behavior of rectangular piles in sloping ground is computationally demanding due to the complex three-dimensional spatial pile-soil interaction. To circumvent the inefficiency of full-scale numerical modeling and the limitations of conventional p-y methods, this study proposes a simplified analytical framework for rapid preliminary design. By systematically isolating the topographical slope effect and the cross-sectional shape effect, a series of mathematical modification factors, namely the ultimate lateral capacity factor KH, the maximum bending moment factor KM, and the maximum reverse shear force factor KQ, were established utilizing a standard level-ground square pile as the computational baseline. The results indicate that increasing the slope angle from 0° to 30° reduces the lateral capacity by approximately 14–20%, whereas increasing the aspect ratio from 1 to 4 effectively compensates for this reduction, improving the capacity by approximately 75%. However, the correspondingly enhanced flexural stiffness simultaneously triggers a substantial non-linear amplification in both the maximum bending moment and the deep reverse shear force. Benchmark comparisons show a maximum deviation of 4.58% for lateral capacity, while the maximum deviations in bending moment and reverse shear force are 10.43% and 9.78%, respectively. By integrating these modification factors with conventional equivalent calculation methods, this study provides an efficient analytical tool for rectangular pile foundation design in sloping ground.

Experimental Study on Vertical Bearing Characteristics of Prestressed High-Strength Concrete Pipe Pile-Group Foundations

To address the difficulty in accurately evaluating the vertical bearing behavior of prestressed high-strength concrete (PHC) pipe pile-group foundations, this study investigated three single piles and an eight-pile group with a Wang-shaped irregular pile cap through field static loading tests and theoretical analysis. The measured ultimate bearing capacities of single piles D1/D2 and D3 were 7040 and 3000 kN, respectively. For the pile-group foundation, the ultimate bearing state was not reached under the maximum applied load of 15,000 kN, at which the settlement was only 3.52 mm. The pile-head load distribution followed the order corner piles > side piles > inner piles, with corresponding load proportions of approximately 13.9%, 12.9%, and 9.4%. The calibrated API and hyperbolic models predicted the single-pile bearing capacities with errors ranging from 0.23% to 3.40%. The API model better represented the steep-drop portion of the Q-s curve, whereas the hyperbolic model more accurately predicted the initial stiffness and low-load response. For pile-group foundations, the combined equivalent-pier and load-transfer method showed good applicability. The main contribution of this study is to provide field evidence for the vertical bearing and load-transfer behavior of a large-diameter PHC pipe pile group with a Wang-shaped irregular pile cap, extending existing studies that have mainly focused on single piles or conventional symmetric pile groups. The results also provide a quantitative basis for the analysis and design of PHC pipe pile-group foundations in highway bridge engineering.

Model Test Study on the Factors Influencing Anti-Slide Pile Reinforcement in High Backfill Slopes

In civil engineering projects, the practice of partial excavation or backfilling of slopes often results in landslide occurrences because of the redistribution of internal stress within the slope mass. This paper presents the findings from scaled-model tests conducted to investigate the reinforcement of high-fill embankment slopes using anti-slide piles. During the filling process, data were meticulously monitored using strain gauges affixed to the pile bodies and embedded earth pressure cells. The analysis focused on the mechanical behavior, including load–displacement relationships at the pile tops, bending moments, and earth pressures. This study was designed to investigate how anti-slide piles contribute to slope stabilization and to evaluate their load-bearing behavior throughout the backfilling process. Additionally, particle image velocimetry technology was used to capture the variation patterns of the soil surface displacement field, thereby revealing soil displacement deformation and the overall failure mechanism. By integrating mechanical responses with the analysis of the soil displacement field, a more profound understanding of the pile–soil interaction mechanism was attained. This experimental method provided a comprehensive depiction of the entire process, from the initial slope movement to its eventual deformation and failure. The research indicates that a reduction in pile spacing leads to a decrease in the maximum bending moment of the pile body, thereby enhancing slope reinforcement. For the same pile spacing, the pile located on the first-level slope platform shows the smallest horizontal displacement at its top after deformation. The soil on either side of the anti-slide pile disperses outward from the pile body, with the maximum displacement occurring directly beneath the pile tip.