The team focused on a type of structure that is deceptively common: a bridge pier founded on a group of piles, embedded in a slope affected by a slow-moving landslide. Unlike catastrophic, fast-moving slope failures that destroy bridges in seconds, slow-moving landslides creep at rates of millimeters to centimeters per year, often going unnoticed until cumulative deformation begins to distort the superstructure or crack the foundations. Yet these quiescent masses of soil are not necessarily benign. When an earthquake arrives, the weakened, sheared, and sometimes saturated landslide material can be reactivated, subjecting the piles to a combination of inertial forces from the shaking structure and kinematic forces from the moving ground. The study’s central question was deceptively simple: does the state of the slope before the earthquake matter for the pier’s seismic performance?

To answer it, the researchers built a nonlinear finite element model of the coupled soil-foundation-structure system, using a reference case study chosen precisely because it is paradigmatic of the numerous Italian bridges located in areas exposed to both seismic and hydrogeological hazards. Bridge piers, after all, may sit on the crest of a slope, along its face, or downstream of it, and the relative position of the bridge and the slope strongly influences the type and severity of the actions the structure must resist. The numerical model captured the essential mechanics of the problem: the nonlinear, strain-dependent behavior of the soil under cyclic loading, the interaction between the piles and the surrounding ground, and the dynamic response of the pier itself.

The analysis compared three distinct scenarios. In the first, the pier stands in a stable slope, representing the conventional design assumption in which the ground is competent and the only seismic demand comes from the shaking itself. In the second, the slope hosts a quiescent landslide that the earthquake reactivates, so the ground begins to move as the shaking progresses. In the third, the landslide is already active before the earthquake, meaning the piles have already accumulated deformation and stress from the creeping soil. This progression allowed the researchers to isolate the influence of pre-seismic slope conditions on the dynamic response of the pier, something that standard seismic assessment procedures, which typically assume stable ground, simply do not address.

The results, expressed in terms of maximum and residual displacements and rotations of the pier, show that the starting condition of the slope is far from a secondary detail. When the landslide is active before the earthquake, the piles enter the seismic event already stressed and deformed, and the ground movement during shaking adds kinematic demands on top of the inertial ones. The interaction between the two loading mechanisms can amplify displacements and, critically, leave the pier with larger residual deformations after the shaking stops. Residual displacement matters enormously for bridges, because permanent tilting or lateral shifting of a pier changes the geometry of the deck, alters load paths, and can compromise serviceability or trigger collapse even when the structure survives the earthquake itself.

Underpinning these findings is the physics of soil-structure interaction, a phenomenon that simplified design methods often reduce to a set of springs or, worse, ignore altogether. In reality, the piles, the surrounding soil and the pier form a single dynamic system whose response depends on the stiffness and damping of every component. Decades of research, from classical work on dynamic pile stiffness to modern studies of kinematic pile bending in layered soils, have shown that the ground is not a passive support but an active participant in the seismic response. The new study extends this understanding to the multi-hazard setting, demonstrating that the dynamic properties of a slope containing a landslide mass differ from those of a stable slope, and that these differences propagate directly into the demands on the foundation.

The Italian context gives the work particular urgency. The national landslide inventory compiled by the Institute for Environmental Protection and Research documents hundreds of thousands of landslide phenomena across the country, and recent research has catalogued extensive interactions between landslides and bridge foundations in Italian case studies. At the same time, Italy has endured repeated bridge failures, some linked to the degradation of structures subjected to unanticipated environmental actions. The national guidelines for classifying and managing the risk of existing bridges, introduced in 2020 and operationalized in subsequent years, pushed owners to assess their assets systematically, and recent technical guidance has begun to address landslide interaction explicitly. The new study provides a quantitative basis for that effort, showing what is at stake when a bridge pier’s foundation crosses a slowly moving mass of soil.

What makes the study especially valuable for practitioners is its methodological clarity. By using a nonlinear finite element approach within a single consistent model, the researchers could track the full path from static slope condition to dynamic seismic response, capturing the state of stress and strain in the soil at the moment the earthquake begins. This matters because the initial stress state governs how the soil stiffens or softens under cyclic loading, how pore pressures evolve, and how much permanent deformation accumulates. The approach also reflects the reality of earthquake-triggered landslide reactivation, a phenomenon documented in devastating detail after events such as the 2008 Wenchuan earthquake in China and the 2016 Kumamoto earthquakes in Japan, where seismically induced slope failures destroyed bridges that had performed adequately under shaking alone.

The broader message is a call for multi-hazard thinking in the assessment and retrofit of existing infrastructure. A bridge evaluated only for seismic loads, assuming stable ground, may be far more vulnerable than its safety factor suggests if it stands in the path of a slow-moving landslide. Conversely, retrofit strategies designed for landslide stabilization alone may leave the structure exposed to seismic demands that the modified soil-foundation system now transmits differently. The authors argue that accounting for soil-foundation-structure interaction is essential when assessing the seismic response of bridge piers in the presence of slow-moving landslides, and that a multi-hazard approach is needed to enhance both the assessment of existing bridges and the sustainability of retrofit strategies. As climate change alters rainfall patterns and slope hydrology, and as seismic hazard remains a permanent feature of the Mediterranean landscape, the quiet creep of a hillside may prove to be the hidden variable that determines whether the next earthquake is survivable for the bridges that carry our lifelines.

Subject of Research: Seismic response of pile-supported bridge piers founded in slopes affected by slow-moving landslides

Article Title: Seismic response of a pile-supported bridge pier under multi-hazard conditions in slow-moving landslides: a numerical investigation

Article References: Ambrosino, A., Servodio, M., Sica, S., Losanno, D., Parisi, F., & Santolo, A. S. D. (2026). Seismic response of a pile-supported bridge pier under multi-hazard conditions in slow-moving landslides: a numerical investigation. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02678-4

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02678-4

Keywords: soil-structure interaction, landslides, earthquake engineering, multi-hazard assessment, bridge piers, pile foundations, finite element analysis, slope stability, seismic retrofit, geotechnical engineering, infrastructure resilience, residual displacement

The scale of the opportunity is considerable. The buildings and construction sector accounted for roughly 34 percent of global energy-related carbon dioxide emissions according to the most recent Global Status Report for Buildings and Construction, and the manufacture of cement and steel remains one of the largest sources of industrial greenhouse gases worldwide. As operational emissions fall through better insulation and renewable energy, attention has shifted to embodied carbon, the emissions locked into materials, transport, construction and demolition. Whole-building benchmarking studies suggest that foundations can represent a significant share of structural embodied carbon, particularly where poor ground conditions or heavy loads demand deep foundations. Academic work has already shown that geometric optimisation, ribbed and hollow pile systems, and alternative materials such as timber or concretes incorporating supplementary cementitious materials can cut the embodied carbon of piled foundations by more than 70 percent while still satisfying structural and geotechnical requirements.

Yet the new research reveals a stubborn gap between what is possible in the design office and what happens on site. Kareem Abushama and colleagues, working with Will Hawkins, Loizos Pelecanos and Tim Ibell, conducted semi-structured online interviews lasting 45 to 60 minutes with five geotechnical consultants and five piling contractors, all with between 11 and 30 years of experience and most holding senior technical or managerial roles. Using Braun and Clarke’s thematic analysis, the team distilled the transcripts into twenty codes and seven themes, grouped into two opposing forces they call Brakes and Accelerators. Data collection continued until thematic saturation, with no substantively new themes emerging beyond the tenth interview, lending weight to the conclusion that the concerns expressed are genuinely representative of mainstream UK practice rather than the views of a few outliers.

The most powerful brake, cited by every single participant with 47 mentions, is commercial and temporal priority. Cost, the interviewees reported, accounts for 80 to 90 percent of the weighting at tender stage, and even a 5 percent premium is difficult to justify without a tangible additional benefit. Testing that could validate an innovative design is routinely sacrificed because, as one participant put it, there is just not time before you start on site. Consultants described client expectations and fee competitiveness; contractors described programme risk and construction efficiency. The result is a decision environment in which sustainability ambitions, however sincere, are systematically subordinated to the twin imperatives of lowest initial cost and fastest delivery, unless environmental value is explicitly tied to financial certainty through mechanisms such as carbon taxation or procurement rules.

Just beneath the commercial pressure lies a deeper cultural force: risk, liability and conservatism, which attracted 40 mentions and was again cited by all ten experts. Foundation failure is catastrophic and highly visible, professional indemnity insurance is expensive, and the person who specifies an unproven solution carries the liability if it underperforms. Participants described a pervasive reluctance to be the first to try, with one consultant stating he would need five projects proving a technology before he would be comfortable specifying it, even after five years of testing a novel pile. The industry, several noted, over-designs quite a lot because it is safer and easier to justify to a client. Historical factors of safety of 2.6 to 3.0 and conservative Eurocode partial factors still push designers towards over-compliance, and poor-quality or low-resolution ground investigation data force conservative assumptions that contribute to systematic over-design. One expert explained that limited geotechnical data necessitates conservative design assumptions, which consequently contribute to systematic over-design, a feedback loop that burns carbon simply to buy certainty.

Constructability adds a further layer of friction. Contractors questioned the practicality of complex optimised geometries when standard augers and casings come in 150-millimetre increments, and described quality-control risks when misaligned precast components require extra machinery and labour to correct. Durability loomed equally large: participants expressed deep nervousness about the long-term performance of more exotic concrete mixes over a 120-year design life, and explained why timber piles, despite their carbon-sequestering appeal, are unsuited to Britain’s wet, dry, temperate climate and fluctuating water tables, unlike the preserved piles of Venice or Amsterdam. Market structure compounds the problem, with consultants reluctant to specify a solution that only one contractor can provide because clients want to go to competitive tender, effectively penalising single-source innovations however promising their performance.

Against these brakes, the interviews identified clear accelerators. The most frequently cited, with 37 mentions and unanimous agreement, is the requirement for empirical proof: full-scale testing, documented case studies and official guidance from bodies such as CIRIA, BRE, ICE and the codes themselves. Participants stressed that authoritative guidance is needed to unlock a lot of interest and to convince insurers and warranty providers, who are often the real gatekeepers of innovation. Collaboration and dissemination, cited by all participants with 35 mentions, formed a second accelerator, with practitioners urging researchers to get out on site and watch people building piles to ensure solutions are practical, and recommending trade magazines such as Ground Engineering over long journal papers because they are what the industry actually reads. Practical, accessible design tools, with several participants noting that anything to do with Excel is great, ranked alongside early contractor engagement as prerequisites for translating academic optimisation into routine specification.

The study’s authors argue that the challenge is not a deficit of technical capability but a deficit of trusted knowledge pathways that translate research into design practice. Their proposed roadmap is a coordinated, system-level response: independently funded full-scale testing programmes, potentially through facilities such as Constructionarium, to validate alternative pile geometries and materials under conditions representative of a 120-year design life; transparent design tools that let engineers evaluate embodied carbon alongside capacity, serviceability and cost within standard workflows; and an open-access database of pile load tests and long-term performance data to allow progressive reductions in conservatism without sacrificing reliability or professional indemnity. Policy levers, including embodied carbon caps in public procurement and infrastructure tenders aligned with frameworks such as PAS 2080, would shift decision-making from lowest initial cost towards whole-life value. Responsibilities are distributed across the ecosystem: researchers must generate reproducible evidence on failure modes and boundary conditions, consultants must integrate carbon as a routine design parameter, contractors must validate constructability early and share performance data, and clients, especially in the public sector, must create demand through carbon reporting requirements and value-based procurement.

What makes the findings compelling is their timing. Regulatory frameworks and emerging planning requirements for whole-life carbon disclosure are progressively reshaping the sector, and substructures, historically exempt from detailed carbon scrutiny, are beginning to face explicit embodied carbon reporting and, in some cases, performance thresholds. As those requirements intensify, the long-standing reliance on conservative do-minimum foundations is likely to become commercially and strategically disadvantageous, and the ability to propose optimised low-carbon pile solutions may shift from discretionary innovation to competitive necessity. The Bath team’s verdict is ultimately optimistic: the brakes are entrenched but identifiable, the accelerators are actionable, and with codified innovation, accessible tools, shared data and clear client demand, the industry could move from a lowest-cost paradigm to a whole-life value paradigm, unlocking the substantial carbon-saving potential already demonstrated in the laboratory and the design office, and finally bringing the hidden half of the built environment into the net-zero equation.

Subject of Research: Barriers and enablers to decarbonising deep pile foundations in UK geotechnical practice

Article Title: Barriers and enablers to the decarbonisation of deep foundations in the UK: Insights from geotechnical industry experts

Article References: Abushama, K., Hawkins, W., Pelecanos, L., & Ibell, T. (2026). Barriers and enablers to the decarbonisation of deep foundations in the UK: Insights from geotechnical industry experts. Environmental and Sustainability Indicators, 32, Article 101521. https://doi.org/10.1016/j.indic.2026.101521

Image Credits: AI Generated

DOI: 10.1016/j.indic.2026.101521

Keywords: embodied carbon, pile foundations, geotechnical engineering, decarbonisation, UK construction, net zero, thematic analysis, risk aversion, sustainable construction, ground investigation, piling contractors, whole-life carbon