Wednesday, July 08, 2026

New field-tested design framework improves bored pile foundations in weathered rock

Analysis of 20 instrumented pile load tests shows that weathering-adjusted rock strength enables more reliable bored pile foundation design

Shibaura Institute of Technology

Data-driven adhesion factors for safer and more efficient bored pile design in weathered siltstone and sandstone — image:
Researchers from Shibaura Institute of Technology analyzed instrumented load-test data from large-diameter bored piles in weathered siltstone and sandstone to develop practical adhesion factors and shaft-resistance correlations for foundation design.
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Credit: Professor Shinya Inazumi from Shibaura Institute of Technology, Japan

Large-diameter bored piles are essential for major infrastructure, from elevated railways and long-span bridges to high-rise buildings. Yet, when these piles extend into weak, weathered sedimentary rocks such as siltstone and sandstone, engineers face a persistent design challenge: the rock behaves neither like conventional soil nor like strong, intact rock. Instead, its load-bearing capacity depends heavily on in-situ weathering, fracturing, and the interaction between the pile and the surrounding rock. Many current design methods estimate shaft resistance using the uniaxial compressive strength of intact rock. However, intact rock strength alone does not accurately represent the weaker, weathered rock mass surrounding a pile socket. As a result, engineers may adopt overly conservative designs, leading to larger pile diameters, greater pile lengths, increased material use, and higher construction costs.

To address this gap, a research team led by Professor Shinya Inazumi from Shibaura Institute of Technology (SIT), Japan, developed empirical design correlations for bored piles installed in weathered siltstone and sandstone. The study was made available online on June 15, 2026, and will be published in Volume 31 of the Results in Engineering journal on September 1, 2026. The team analyzed data from 20 instrumented static axial load tests on bored piles with diameters of 1.2–1.5 m and lengths of 9.3–36.0 m. “The combined effects of rock weathering, in-situ rock strength, and adhesion factor (α) on the shaft resistance of bored piles in weak rock remain poorly understood, motivating the need for further site-specific empirical studies,” said Prof. Inazumi.

All piles were constructed using the wet-process method and equipped with strain gauges and extensometers, allowing the researchers to measure unit shaft resistance and layer displacement along the pile depth. For weak rock layers where the measured displacement did not reach 5 mm, the team used hyperbolic fitting to estimate shaft resistance at this representative working displacement. A key aspect of the study was the explicit incorporation of rock weathering. The researchers adjusted the intact rock strength using a weathering-based reduction factor to calculate an equivalent in-situ rock strength. This enabled them to compare conventional estimates based on intact rock strength with weathering-adjusted estimates that more accurately reflected field conditions at the pile-rock interface.

The results revealed clear differences between the two rock types. For siltstone, 11 layers yielded adhesion factors ranging from 0.08 to 0.42, whereas six sandstone layers showed adhesion factors between 0.04 and 0.10. In practical terms, siltstone mobilized adhesion factors roughly twice those of sandstone under comparable conditions. Moreover, the weathering-adjusted correlations reduced prediction bias and variability compared with estimates based solely on intact rock strength. The proposed framework can be applied in two stages. During preliminary design, engineers can estimate shaft resistance using intact rock strength and rock type. During detailed design, they can incorporate the degree of weathering along the pile socket, calculate weathering-adjusted rock strength, and apply the proposed adhesion-factor correlations. This provides a more field-calibrated pathway from subsurface investigation to foundation design.

The findings are especially relevant for bridges, high-rise buildings, retaining structures, quay walls, transportation hubs, water-treatment plants, and energy facilities built on weak sedimentary rock profiles. By improving confidence in shaft-resistance estimates, the approach can help reduce unnecessary overdesign while maintaining safety and serviceability. “The proposed empirical correlations provide a field-based framework for estimating the shaft resistance of large-diameter bored piles in weak sedimentary rock formations, highlighting the importance of explicitly accounting for rock weathering in pile design,” notes Prof. Inazumi.

The authors caution that the proposed correlations should be applied only within the tested geological conditions and parameter ranges, and that additional validation is needed for other weak rock types such as mudstone and shale. Nevertheless, the study offers a practical, field-based framework for improving foundation design in weathered sedimentary rock formations. By enabling more reliable estimates of pile capacity, it has the potential to support safer infrastructure while reducing unnecessary material use and construction costs.

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Reference
DOI: 10.1016/j.rineng.2026.111565

About Shibaura Institute of Technology (SIT), Japan
Shibaura Institute of Technology (SIT) is a private university with campuses in Tokyo and Saitama. Since the establishment of its predecessor, Tokyo Higher School of Industry and Commerce, in 1927, it has maintained “learning through practice” as its philosophy in the education of engineers. SIT was the only private science and engineering university selected for the Top Global University Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology and had received support from the ministry for 10 years starting from the 2014 academic year. Its motto, “Nurturing engineers who learn from society and contribute to society,” reflects its mission of fostering scientists and engineers who can contribute to the sustainable growth of the world by exposing their over 9,500 students to culturally diverse environments, where they learn to cope, collaborate, and relate with fellow students from around the world.

Website: https://www.shibaura-it.ac.jp/en/

About Professor Shinya Inazumi from SIT, Japan
Dr. Shinya Inazumi is a Professor at the College of Engineering, Shibaura Institute of Technology (SIT), Japan, where he leads the Geotechnical Engineering Laboratory. He obtained his Master’s and PhD degrees in Engineering from Kyoto University in 2000 and 2003, respectively. With over two decades of academic and research experience, he has authored more than 250 journal papers. His research focuses on geotechnical engineering, geo-disaster mitigation, sustainable social infrastructure, soil and ground improvement, numerical simulations, and AI applications in infrastructure planning. His notable achievements include best paper recognition at GEOMATE 2023 and editorial board honors.

Journal

Results in Engineering

DOI

10.1016/j.rineng.2026.111565

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Adhesion factors for bored piles in weathered siltstone and sandstone based on instrumented load tests

Article Publication Date

1-Sep-2026

Cheetah chases inspired researchers to make a biologically accurate video game

Society for Experimental Biology

image:
The species selection screen from Run FoVE Your Life.
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Credit: Baptiste Morel

Movement data from wild predator-prey encounters and controlled human catch-tag games have been combined to create realistic simulations of high-intensity movement dynamics and energetics – before transforming them into a publicly accessible video game. This game utilises a citizen science approach to data collection and is helping to further our understanding of the role of movement decision-making and fatigue in life-or-death encounters.

Intense physical exertion during predator-prey chases can trigger fatigue in both participants, which is defined as the reduction of muscle and movement capacity when operating above a critical threshold. The ability of an animal to capture or elude its opponent is often determined by its capacity for speed and agility before becoming fatigued.

This project, presented at the Society for Experimental Biology conference in Florence, Italy, highlights how real movement data have been captured and transformed into simulated models that allow for human decision-making, so the team can now create more accurate simulations of predator-prey interactions.

Dr Baptiste Morel, an associate professor at the University of Savoie Mont Blanc, France, leads the Force-Velocity-Endurance (FoVE) team that are interested in evaluating the physical abilities of athletes across various sports.

The inspiration for this project came from a collaboration between the FoVE team, who primarily work with human movement, and an ecology lab, who focus on animal movement. “We started to apply the methods that we developed for sports science to the animals in the wild, so we can have an estimation of their physical ability and how much of this ability they will use,” says Dr Morel.

However, high-quality movement data from wild predator-prey chases, comparable to the high-resolution GPS tracking used in professional sports, is limited and practically impossible to produce in controlled conditions. “It’s interesting data because it comes from real life, but it's not possible to control these experiments and understand how their physical ability will lead to fatigue or how the prey might escape or not,” says Dr Morel.

To overcome this data limitation, Dr Morel and his team used human athletes taking part in chase-tag games as models to compare against the wild predator-prey encounters.

“Chase-tag games are not as intense as true predator-prey encounters, as lives are not typically at risk. However, the roles of predator and prey are so deeply ingrained in animal nature that even without real danger, the game still triggers a high level of physical exertion and intense anxiety,” says Dr Morel.

Movement characteristics were captured from 16 human athletes taking part in “chase tag” interactions, including force, velocity and endurance. These pursuit scenarios simulated iconic predator-prey encounters, and the participants’ movements were tracked by high-frequency GPS and accelerometery.

The team investigated fatigue using two methods. Firstly, by having the humans perform a sprint before and after the chase and comparing the reduction in physical capacity to move. Secondly, by taking blood samples to measure the levels of lactic acid, a marker of muscular chemical disruptions that contributes to fatigue.

Control over the chase-tag scenarios enabled the team to capture a wide range of behavioural data. “For example, we ran experiments with ambush predation over really short distances, and others with long-distance tracking,” says Dr Morel.

Over the last year, Dr Morel and his team have used their findings to develop an innovative online game that simulates the real-world predator-prey encounters with a variety of animals, including wolf, deer and humans. Since virtual simulation now makes anything possible, players can even step into the shoes of extinct species like the Tyrannosaurus rex.

Players take the roles of predator and prey species and chase each other across a digital landscape until either the prey is caught or they survive long enough to escape. Real movement and fatigue calculations have been used to improve the realism of the game.

“We thought that this could not only be a really interesting to share our science, but it could also be a participatory way of doing science,” says Dr Morel, who is very interested in assessing how representative the digital game will be compared to the real human data they have collected.

“For example, we have wolf and African wild dog data where they can hunt persistently for several tens of minutes over kilometres of a chase” says Dr Morel. “But the average chase length for a cheetah is just 200 meters because after they ambush, they start to fatigue and usually will not catch an antelope after that.”

The game ‘Run FoVE your life’ will be soon available for people to play online. Anyone with a computer and an opponent will be able to play.

"Predators win" screen from Run FoVE Your Life.

Credit

Baptiste Morel

Lost medieval manuscripts inferred by family tree

PNAS Nexus

image:
Chanson d'Aspremont (a version of the Legend of Roland). Shelfmark: Lansdowne 782.
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Credit: From the British Library archive. E50003-09

For every King Arthur or Roland, whose adventures readers can still enjoy today, another hero of ancient literature may have been lost forever. Before the printing press, texts were copied manually. This process introduced errors and innovations. Like mutations in the replication of DNA, these manuscript changes can be used to create evolutionary trees that philologists call stemmata. Since these trees are based on the extant copies, they do not reflect the full evolutionary history of texts and cannot account for the ones that are completely lost. Jean-Baptiste Camps and colleagues use a complexity science approach to estimate the amount of lost literature among chivalric narratives, beginning in the 12th century. Agent-based simulations suggest that up to 60% of texts and more than 95% of manuscripts may have been lost. The model reveals that the first few years after a text’s creation are key: If few copies are made, the work is at high risk of extinction. The model also suggests that for most texts, no existing copies capture the original state of the work; all surviving texts are likely to be from a subsidiary branch of a given work’s family tree. The oldest version of the Song of Roland is probably unknowable, for example. Seemingly random accidents or major historical contingencies, such as the Black Death, also likely led to the extinctions of texts. According to the authors, cultural heritage is fragile, and the model helps understand how randomness, historical contingencies, and human choices shaped the literature we inherit today.