Mini-Symposia

Filippo Medeghini (Ruhr University Bochum, Germany)
Peter Mark (Ruhr University Bochum, Germany)
Giovanni Plizzari (University of Brescia, Italy)

Daniela Boldini (Sapienza University of Rome, Italy)
Andrea Franza (Aarhus University, Denmark)
Arash Alimardani Lavasan (University of Luxembourg, Luxembourg)
Nunzio Losacco (Politecnico di Bari, Italy)

The design of mechanised tunnelling in urban environments requires the accurate prediction of the effects of excavation, operation, and construction parameters on stability, ground movements and the resulting forces within tunnel linings. This process involves not only assessing the impact of the excavation on nearby structures but also understanding how the characteristics of these structures—such as stiffness and self-weight—could affect the tunnelling process.

Key considerations include the effect of face and tail grouting pressures provided by the tunnel boring machine (TBM), the influence of lining geometry and connections, the role of passive and active reinforcements or barriers, and the challenges posed by complex or skewed tunnel alignments. Additionally, the presence of adjacent tunnels, foundations, and existing nearby tunnels introduces complexities that must be addressed during both the design and construction phases. Numerical methods are crucial in modelling these tunnel-soil and soil-structure interactions, considering short-term effects during excavation and long-term behaviour under static and dynamic loading, such as seismic events or surface construction activities.

This Mini-Symposium aims at exploring effective approaches to achieve reliable and precise predictions, with a focus on the appropriate level of complexity needed in both geotechnical and structural domains. We encourage contributions presenting state-of-the-art numerical simulations under static and dynamic conditions, along with discussions on analytical and simplified solutions derived for routine engineering calculations. Special attention will be given to the validation of numerical approaches using field monitoring data or experimental measurements, as well as the discussion of parameter selection for reliable simulations.

Georgios Anagnostou (ETH Zurich, Switzerland)
Lina-María Guayacán-Carrillo (Laboratoire Navier, École nationale des ponts et chaussées, Institut Polytechnique de Paris, Université Gustave Eiffel, CNRS, France)

After decades of research into the feasibility of safe long-term underground storage of
radioactive waste, the implementation phase is now approaching in several European
countries. As a result, issues relating to the short to medium-term structural safety and
serviceability of the underground structures are coming to the fore. In contrast to longterm nuclear safety issues, which are concerned with processes that evolve over several millennia, the focus here is on much shorter periods, in the order of 70 to 100 years, which covers the period of potential waste retrieval.

Although the construction methods, design approaches and planning procedures are
basically the same as for other civil engineering structures, a number of new questions and challenging problems arise due to nuclear safety requirements (such as maintaining the low permeability of the host formation, or limiting the quantities of certain construction materials) and repository site conditions (e.g. large overburden and high pore pressures, weak ground with complicated mechanical behaviour characterized e.g. by softening, pronounced time-dependent ground response to excavation due to hydromechanical coupling and extremely low permeability, significant thermal effects due to radioactive decay heat, etc.). Addressing such issues requires, on the one hand, advanced and rigorous computational methods that reproduce the behaviour observed in existing experimental facilities and allow reliable analysis of highly non-linear and multiply coupled processes. On the other hand, given the complexity of the processes outlined above, approaches are also needed that are reliable yet simple enough to be implemented in design practice.

The mini-symposium will promote the exchange of knowledge, experience and opinions among those involved in research and development related to proposed geological repositories. The target audience consists of both scientists investigating fundamental issues and engineers contributing to the generation

Bin Liu (Shandong University, China)
Bo Zhang

Jelena Ninić (University of Birmingham, UK)
Qianbing Zhang (Monash University, Australia)
Valentina Villa (Politecnico di Torino, Italy)
Günther Meschke (Ruhr University Bochum, Germany)

Digital, advanced computational, and machine learning technologies hold significant potential for enhancing the resilience of critical infrastructure, including tunnels. While these technologies are widely adopted across the construction industry to improve delivery, performance, and collaboration, their current use does not yet fully leverage the transformative potential of the digital revolution. Deploying these technologies within Digital Twin (DT) frameworks—virtual replicas of physical systems—can establish models that are a real-time single source of truth, integrating data from disparate systems to optimize design, construction, and operation, thereby enhancing productivity and resilience in underground construction.

Digital Twins combine 3D digital models with data, Machine Learning (ML), numerical models, and advanced data analytics to create dynamic simulations that continuously update based on changes in the physical counterpart across its lifecycle. These simulations enable process optimization, decision support, virtual control, and analysis. This Mini symposium invites contributions on all enabling technologies for Digital Twins in underground construction, including but not limited to:

• Information and digital modelling in underground construction
• Computational modelling, machine learning approaches for surrogate modelling, and data-model fusion in tunnelling
• Uncertainty modelling, inverse analysis, and parameter identification methods
• Design optimization and risk analysis
• Computer vision, soft computing, visualization, data mining, and expert systems in tunnelling
• Advanced multi-phase and multi-scale modelling for soils, rocks, and support structures
• Process and logistics modelling

Arash Alimardani Lavasan (University of Luxembourg, Luxembourg)
Frédéric Collin (University of Liege, Belgium)
Torsten Wichtmann (Ruhr University Bochum, Germany)

The accurate modelling of tunnel behaviour requires a thorough understanding of the constitutive behaviour of soils and rocks under complex loading and boundary conditions, where hydromechanical interactions are often critical. In tunnelling applications, coupled processes such as multiphase flow and mechanical deformation in sands, clays, and soft rocks significantly influence both short-term excavation stability and long-term tunnel performance. Accounting for the key phenomenological aspects including pore pressure evolution in sands, consolidation and creep in clays, and swelling or squeezing behaviours as well as tunnelling-induced damages in soft and sensitive rocks, require an adequate constitutive models to address the soil and rock behaviour along with an advanced coupled computational model to accurately capture their impact on tunnel design and operation. Moreover, coupled computational modelling is a crucial step to address the material properties variation in non-isothermal conditions and to study the pore pressure evolution, expansion or contraction of soils and rocks due to temperature variations in the underground space.

This Mini-Symposium aims to advance the understanding of constitutive models for soils and rocks and to discuss innovations in coupled Thermo-hydro-mechanical computational methods. Contributions are encouraged that present state-of-the-art numerical simulations and computational modelling approaches to capture these interactions for practical engineering applications. Special emphasis will be placed on the development and validation of constitutive models using field monitoring data or experimental studies, as well as discussions on parameter selection and calibration strategies to enhance predictive reliability in challenging tunnelling environments. Additionally, contributions addressing computational methodologies for modelling tunnel-induced coupled interactions and those involving field monitoring data are welcomed.

Bernhard Pichler (TU Wien, Austria)
Christian Hellmich (TU Wien, Austria)
Jiaolong Zhang (Tongji University, China)

Structural monitoring plays a crucial role in tunneling, providing essential data to make informed decisions and mitigate potential problems before they escalate. It helps ensure the safety of workers during construction and of the public once the tunnel is operational. Additionally, structural monitoring facilitates proactive maintenance and repair, as well as optimizing the design and construction processes for ongoing and future tunnel projects. This minisymposium aims to bring together leading researchers and engineers specializing in the computational analysis of tunnel monitoring data. To foster a dynamic dialogue among experts in the field, we invite papers that offer valuable insights into the structural behavior of tunnel linings and their interaction with the surrounding ground mass. Papers that highlight innovative methodologies, case studies, as well as advances in monitoring technologies and related evaluation techniques are particularly encouraged.

Mario Wölflingseder (Graz University of Technology, Austria)
Thomas Marcher (Graz University of Technology, Austria)
Peter Gamnitzer (University of Innsbruck, Austria)
Günter Hofstetter (University of Innsbruck, Austria)

The New Austrian Tunneling Method (NATM) is widely employed due to its adaptability to varying geological and geotechnical conditions. Numerical modeling has become an essential tool in the design, optimization, and monitoring of NATM projects, allowing engineers to predict deformations and stress distributions during construction.

This mini-symposium aims to advance numerical modeling techniques for enhancing the effective application of NATM. Key topics include finite element, finite difference, and discrete element methods for simulating excavation and reinforcement sequences, as well as their limitations. Special emphasis is placed on constitutive models, including those accounting for anisotropy, swelling rock conditions, and transitional material behavior (e.g., hard soil/soft rock). The selection of appropriate constitutive models, parameter identification, and adherence to geomechanical design guidelines are critical focus areas.

The symposium will also explore advanced 3D analyses, incorporating tunnel support ahead of the tunnel face, complex excavation sequences, radial support, pre-support elements, and concrete models for shotcrete. By integrating these aspects with cutting-edge research and case studies, the event fosters a deeper understanding of simulation approaches, promoting innovation in NATM tunneling methods and addressing the challenges of deep-seated rock tunnels and shallow tunneling in soil or transitional materials.