In an era of increasingly complex and ambitious civil engineering projects, the importance of robust, efficient, and well-understood foundation systems cannot be overstated. Piled foundations, in particular, have long been a cornerstone of geotechnical engineering, enabling the construction of towering skyscrapers, expansive bridges, and critical offshore structures. Yet, as our built environment evolves to meet the challenges of the 21st century, so too must our understanding and application of piled foundation technology.
This themed issue, ‘Piled foundation behaviour: monitoring, modelling and measurement,’ brings together cutting-edge research that pushes the boundaries of our knowledge in this critical field. The ten papers presented herein offer invaluable insights into advanced monitoring methods, complex interactions between piles and surrounding soil, and innovative installation techniques. The importance of this theme is underscored by the growing demands placed on our infrastructure. As urbanisation accelerates and we venture into more challenging environments both onshore and offshore, the need for precise, reliable foundation solutions becomes ever more acute. Moreover, the increasing focus on sustainability in construction necessitates optimised designs that minimise material usage while maximising performance — a goal that can only be achieved through a deeper understanding of pile behaviour.
One of the most exciting developments in pile foundation technology is the application of advanced monitoring techniques. The paper by Höttges et al. (2024) showcased a novel methodology for assessing the geometry of self-drilling micropiles (SDMs) using distributed fibre optic sensors. This approach not only offers unprecedented insight into pile geometry but also holds promise for real-time structural health monitoring. Such innovations are crucial for reducing uncertainty in pile design and installation, particularly for techniques like SDMs that offer significant time and cost savings but have historically been limited by geometric uncertainties. The theme of monitoring is further explored in the comprehensive nine-year case study of a wide pile group supporting three 70-storey towers (Buttling et al., 2024). This long-term study provides invaluable data on load distribution and settlement patterns, highlighting the complex interplay between pile groups, mat foundations, and underlying soil layers. Such longitudinal studies are rare yet essential for validating and refining our design methodologies for large-scale foundation systems.
Advancements in modelling techniques form another crucial aspect of this issue. The paper by Ma et al. (2023) on calculating screw pile bearing capacity using the limit equilibrium theory offers a refined approach to optimising screw pile design. Similarly, Rahimi et al. (2024) presented a database approach on hyperbolic load-displacement behaviour of helical and expanded piles, providing a data-driven framework for predicting pile performance. These analytical tools, when combined with empirical data, enable engineers to design more efficient and reliable foundation systems. Full-scale tests were conducted to investigate the mechanical response of a cast-in-place energy pile beneath a liquefied natural gas (LNG) tank in Zhang et al. (2024). Such experimental setting enables accurate replication of the complex thermo-mechanical loads an energy pile experiences under real-world operational conditions.
The dynamic behaviour of piles under torsional loads is a theme that runs through several papers in this issue. Sallam et al. (2023) investigated the performance of fin piles subjected to torsional loads in dry sand, demonstrating the efficiency gains from this innovative design. Two papers by Li et al. (2024) and Feng et al. (2023) explored the torsional dynamic loading on pile foundations, with one focusing on the circumferential support of surrounding soil and the other examining the influence of pile end soil considering stress diffusion. These studies shed light on a critical yet often overlooked aspect of pile behaviour. As our structures grow taller and are subjected to more complex loading conditions, understanding and mitigating torsional effects becomes increasingly important.
Installation methods and their effects on pile performance are another key focus. Massarsch (2023) presented a detailed study on soil resistance during vibratory driving in sand, offering insights into the mechanism of shaft resistance reduction during installation. Complementing this, Stein (2024) compared stress effects due to different installation methods for pipe piles in sand, providing crucial insights into the advantages and limitations of vibratory driving versus traditional impact driving. This research is particularly relevant as the industry seeks more environmentally friendly and efficient installation techniques, especially for offshore applications.
In conclusion, this themed issue serves as a testament to the vibrant and critical nature of research in piled foundation behaviour. By bringing together diverse studies on monitoring, modelling, and measurement, we hope to inspire further innovation and collaboration in the field. As we look to the future, it's clear that the field of piled foundations will continue to evolve. The integration of smart sensors, advanced materials, and data-driven design approaches promises to revolutionise how we conceive, construct, and monitor foundation systems. Moreover, as we grapple with the challenges of climate change and urban resilience, innovative pile technologies may play a crucial role in adapting our infrastructure to changing environmental conditions.
