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Programme

Monday 12 october 2026

12.10.2026
10:30 - 12:20
Théâtre Marie Curie
A. Sustainable solutions to environmental challenges
OPENING CEREMONY

10:15-10:30
Welcome and registration of participants

10:30-10:35
Welcome address by the Congress President
Philippe MILLARD (Argenteuil, France)

10:35-10:45
Welcome to the Lille metropolitan area.
Michel Delepaul, Vice-President of the European Metropolis of Lille

10:45-10:55
Address by the President of AFTES
Hubert TOURNERY (Paris, France)

10:55-11:00
Address by the President of the International Tunnelling and Underground Space Association (ITA-AITES)
Andrea PIGORINI (Rome, Italy)

11:00-11:15
Update on the CIGEO radioactive waste disposal project
Lydie EVRARD, Director General of ANDRA (Chatenay Malabry, France)

11:15-11:30
The Grand Paris Express and the Metropolitan Regional Express Services projects
Bernard CATHELAIN, Member of the SGP Executive Board (Paris, France)

11:30-11:45
Entertainment

11:45-11:50
European Underground & Tunnel Forum (EUTF): review and outlook
Éric LECA, President of the EUTF (Paris, France)

11:50-12:10
The European Union and transport: Trans-European corridors and transport funding policy
Mathieu GROSCH, European Coordinator for the Mediterranean Corridor of the TEN-T network, European Commission

12:10-12:20

Address by Éric Prémat, Deputy Director of CETU.

Eric PREMAT - CETU (Bron, France)

12:20

Official opening of the exhibition

12.10.2026
12:30 - 14:00
LUNCH BREAK

LUNCH BREAK

12.10.2026
13:20 - 13:50
e-poster station 1
Commented e-posters
COMMENTED E-POSTERS SESSION 1

13:20 - 13:28
Collapse of the Schieburg tunnel in Luxembourg: geological causes and emergency securing works
Steve GRUSLIN (Contern, Luxembourg)

13:30 - 13:38
3D pre-design: a key driver of BIM on the L15 West, Southern Section of the Grand Paris Express project
Omaima AKILI (Choisy-Le-Roi, France)

13:40 - 13:48
Post-Thaw Behavior of Artificially Frozen Soils: Implications for the Long-Term Performance of Urban Underground Infrastructures
Zeina JOUDIEH (Guyancourt, France)

On 27 August 2022, a collapse occurred in the Schieburg tunnel during repairs to the vault. Around 400 m³ of debris fell in a matter of seconds, completely blocking the tunnel and the only railway line serving northern Luxembourg towards Belgium. The rockfall occurred 60 m from the southern entrance, at a point where the overburden above the tunnel is 31 m. The geological and geotechnical studies carried out included reconnaissance boreholes extending to a depth of 80 m, with parameter recording, geophysical surveys using electrical and seismic tomography, and a structural study of outcrops in the vicinity of the tunnel. These investigations revealed a highly complex geological situation, with the rockfall zone located at the intersection of a system of conjugate faults not recorded on geological maps. The results made it possible to estimate the volume and shape of the deconsolidated zone above the collapse and to propose safety measures to reinforce the deconsolidated zone above the tunnel, safely remove the cone of debris, and repair the vault. Geotechnical monitoring was carried out throughout the safety works, enabling the tunnel to be reopened less than one year after the collapse, despite very difficult access conditions. --- BIM is widely deployed in construction projects, but its overall integration with infrastructure projects remains still recent, particularly for metro lines. The implementation of an innovative 3D "pre-synthesis" (PSY) process on the project mentioned in the subject, by the holder of the contract awarded in COREA (Design & Production), and covering all disciplines (civil engineering, state technical corps and station facilities, transport systems & transversal systems) marks an important evolution. This approach, initiated at the design phase (AVP and then PRO), was identified as a strong point by all project stakeholders, including the Société des Grands Projets (SGP), the "third-party" prime contractors acting as interfaces, and of course the internal partners of the COREA Group. The project, which was the first awarded in design-build (CR) by the SGP in mid-2023, saw the completion of its Design phase (PRO-2) in 2025, and work has been gradually initiated in parallel at the Project’s 22 sites, including 5 underground stations and 17 service structures. The design is the result of a close and multi-disciplinary collaboration between engineering and architecture teams, involving more than 300 people. This project also involves a strong collaboration with the film companies, initiated during the offer phase. Collaboration with the third-party EOMs in charge of transverse systems is finally a key element. Three levels of presynthesis have been defined: • An internal PSY, to coordinate the production of integrated project management teams (MOEI), • An external PSY, to integrate the contributions of work entities within the COREA Group, • An external PSY, to collaborate with third-party EOMs (TMs) on the interfaces within their scope, with the consortium ensuring overall BIM management. To structure this approach, the Autodesk Construction Cloud (ACC) platform was used, notably the Docs modules for external exchanges and Model Coordination for internal coordination. The innovation lies in the use of plugins between Navisworks, Revit and ACC, allowing an automatic synchronization of detected conflicts, as well as the automatic and regular compilation of models, without manual intervention. The PSY manager thus benefits from a centralized and updated environment, allowing him to effectively monitor coordination topics and fully assume his role as conductor of synthesis. --- Artificial Ground Freezing (AGF) is widely used in underground construction to create a temporary watertight and mechanically reinforced soil mass by converting porewater into ice. Although AGF provides effective short-term ground support, the mechanical behavior of thawed soils remains poorly understood, particularly in dense urban environments where long-term stability is critical. This study investigates the freeze–thaw (FT) behavior of a silty sand under thermal and mechanical conditions representative of AGF applications. Tests were conducted using a temperature-controlled oedometer capable of applying vertical stresses up to 5000 kPa to simulate the impact of the overburden pressure, while imposing an upward freezing gradient. Results highlight the strong influence of applied stress on both freezing and post-thaw behavior. Under low applied stress (30 kPa), frost heave reached 6.8 mm, followed by large thaw settlement and structural weakening, indicating loss of stiffness and increased post-thaw compressibility. In contrast, under high applied stress (1000 kPa), ice lens formation was limited, leading to reduced heave and a post-thaw hardening effect associated with stress-induced densification. The temperature gradient significantly affected deformation, particularly under low stress. Overall, the results show that the applied stress during freezing governs both the magnitude and nature of FT-induced deformations. Recognizing this behavior is essential for AGF design, ensuring deformation control and long-term performance of underground structures in urban environments.
12.10.2026
13:20 - 13:50
e-poster station 2
Commented e-posters
COMMENTED E-POSTERS SESSION 1

13:20 -  13:28

TELT CO7 project: Construction of an Inner Concrete Lining in a Segmental Tunnel Using an Internal Structure Installation Gantry 

Marie COBLARD Setec Tpi (Paris, France)

13:30 -  13:38

Segment Erection Assistant

Jean-Camille BROCHARD (Saint-Jory, France)

13:40 -  13:48

Incorporating Water Pressure Effects into Chloride Migration Modelling for Underground and Marine Structures

Luke MARRIOTT Atkinsrealis (London, United kingdom)

The TELT project aims to create a new mixed freight and passenger train line though the Alps, between France and Italy. Its main feature, the Mont Cenis base tunnel is currently under construction and is set to become one of the longest railway tunnels in the world upon its completion. The operational sites CO6/7 are responsible for the construction of 23 km of the base tunnel through one of the most geologically complex zones of the Alps. A 9 km geognostic gallery, previously excavated by a single shield TBM during feasibility works is currently being repurposed as a part of the base tunnel itself. Although already lined by concrete precast segments, studies showed that a cast in place concrete lining would be required to resist the loads over the tunnel life span. Due to feasibility constraints, coactivity in the gallery and security reasons, the CO6/7 opted for the use of an Internal Structure Installation Gantry, also known as ISIG to construct the invert of this definitive lining. Composed of multiple working zones dedicated to waterproofing, rebar installing and concrete pouring, the structure also allows vehicles to drive over itself. --- Erecting a segment ring in a tunnel boring machine is a high-stakes task, but time-consuming and repetitive. Generally, it requires an erector pilot and an assistant who gives positioning instructions. This working mode exposes operators to risks, as the environment involves moving elements and the handling of heavy loads within a confined space. The correct positioning of the segments also depends on effective communication between operators, making installation quality highly dependent on the team. In this context, the SEA (Segment Erection Assistant) was designed to make the process more reliable and faster. This intelligent system provides the erector operator with all necessary information in real time, enabling accurate, rapid, and fully autonomous decision-making. Tested on several construction sites, the system has evolved and now fully meets market expectations. It can be installed on any type of machine, quickly and at any stage of the project. The Segment Installation Assistant system is based on embedded intelligence and offers several major operational advantages: - Time saved on the ring erection cycle as the information is brought directly to the attention of the pilot. - Improved safety by limiting the intervention of the erector pilot assistant. - Reliability of the information transmitted to the erector pilot because the communication chain is automatic and shorter, ensuring an accurate and quick transmission. --- Chloride migration modelling is a well-established methodology for determining appropriate concrete cover depths to reinforcement in structures situated in saline environments. Unlike conventional empirical approaches, such as those outlined in BS 8500-1:2023, this modelling approach enables the specification of tailored cover requirements by accounting for the unique material properties and environmental exposures of individual structures. Guidance on the application of chloride migration modelling is provided in the Concrete Society’s Technical Report 61 and fib Bulletin 34. These references describe diffusion-based transport mechanisms for chloride ions, with no explicit consideration of pressure-driven transport processes, where saline water is forced into the concrete’s pore structure under elevated hydraulic pressures. This mechanism, referred to hereafter as advection, is especially relevant for submerged structures where water pressure can significantly accelerate chloride ingress into concrete and consequently, the onset of reinforcement corrosion. This paper introduces a modification to existing diffusion-based chloride migration models by incorporating advection effects, providing a more accurate representation of chloride transport in underground and marine structures subjected to high water pressures. A comparative analysis is presented, illustrating the differences in calculated cover values when advection is considered alongside diffusion to highlight the implications for service life design in critical infra-structure.
12.10.2026
13:20 - 13:50
e-poster station 3
Commented e-posters
COMMENTED E-POSTERS SESSION 1

13:20 -  13:28

Reassessment of the partial safety factor of flexural tensile strength using tests from the prefabrication of steel fiber-reinforced concrete tunnel segments 

Yi ZHANG - Eiffage Génie Civil (Velizy Villacoublay, France)

13:30 -  13:38

Tunnel design for the “Ligne Directe” railway between Neuchâtel and La Chaux-de-Fonds, Switzerland

Geoffroy AYMERIC - Amberg Engineering Sa (Regensdorf, Switzerland)

13:40 -  13:48

Reference Design of the Deep Tunnel Option for the Sizewell C nuclear power station Tunnel-to-Shaft online and offline Permanent Connections  

Jiang SU - Atkinsréalis (Epsom, United kingdom)

Steel fiber-reinforced concrete (SFRC) is a solution recently deployed in France for the prefabrication of tunnel segments, due to its structural quality, cost-efficiency and durability. The residual flexural tensile strength of SFRC is one of the most important parameters in tunnel segment design. The fib 83 bulletin uses the same partial safety factor for the residual flexural tensile strength of SFRC (γF = 1.5) as for the compressive strength of concrete for reinforced concrete. As part of the follow-up to a large-scale application, this safety factor was re-evaluated based on a reliability-analysis with data from internal control tests carried out on line 16-1 of the Grand Paris Express project. A database of test results from over 730 days' production of SFRC tunnel segments was thus created. This database was used to determine the characteristic values and distribution laws of key parameters in the reliability analysis for re-assessing the partial safety factor γF. More specifically, the various load cases were studied, using both analytical and probabilistic methods. Two values of the reliability index (β = 3.89 and β = 3.72) were considered, associated respectively with a service life of 50 years and 100 years for a reliability class RC2. The results of these analyses demonstrated that the partial safety coefficient γF can be optimized using an appropriate production procedure, accompanied by rigorous quality control and a precisely controlled structural model to reduce the uncertainties associated with soil parameters, installation and consideration of geometric variability. --- La Ligne Directe is a major railway project linking Neuchâtel and La Chaux-de-Fonds (14 km apart), reducing travel time from 28 to 15 minutes with a quarter-hourly service. The project relies on extensive underground works whose design is founded on detailed geological investigations and robust engineering solutions, requiring close collaboration between geologists and engineers. This paper presents the geology and tunnel design developed for the project. The project includes two underground sections, each comprising a main railway tunnel and a parallel service and emergency gallery connected by regularly spaced cross passages, for a total of approximately 24 km of underground works. Geological investigations involved 2,430 m of cored boreholes, intersecting formations from the Lower Jurassic to the Tertiary and crossing complex anticline and syncline structures, numerous faults, and karstified limestone. The paper describes the geological context, geotechnical investigations, design parameters, excavation methods, tunnel support and lining concepts, and presents the key challenges. --- Sizewell C (SZC), a new nuclear power station on England’s east coast, adopts a once-through cooling system with intake and outfall tunnels extending approximately 3 km offshore into the North Sea. These tunnels terminate at vertical shafts founded in complex geology, including Coralline Crag, London Clay, and Harwich Formations. AtkinsRéalis developed the reference design for the Deep Tunnel Option and evaluated online and offline shaft configurations. A key innovation is the integration of soil–structure interaction and structural analysis within a unified PLAXIS modelling environment, eliminating the need for separate geotechnical and structural models and improving efficiency. Seismic performance, critical for nuclear-classified structures, was addressed using a novel methodology combining analytical techniques with advanced numerical modelling to capture three-dimensional tunnel-shaft interactions. PLAXIS 2D and 3D models used volume elements to realistically represent lining thickness and stress concentrations, enabling accurate prediction of required reinforcement and simulation of movement joints. This approach informed reinforcement design and confirmed compliance under static and seismic conditions. Conservative assumptions were adopted for the reference stage, while allowing flexibility for optimisation during detailed design. The design introduces integrated modelling, advanced seismic assessment, and enhanced structural realism, providing a robust and adaptable framework for safe and efficient delivery of critical offshore infrastructure.
12.10.2026
14:00 - 15:30
Room 0.4
Congress Conference
A. Sustainable solutions to environmental challenges
SUSTAINABILITY ASSESSMENT OF UNDERGROUND INFRASTRUCTURE

Chairmen : Michel DEFFAYET (Lyon, France), Nataliya DIAS (Chatenay-Malabry, France)

14:00-14:10
Introduction

14:10-14:30
Sustainability Assessment of Underground Infrastructure – Integrating Socio-Economic Factors and Ecosystem Preservation into the Assessment of Underground Projects
Pierre CARLOTTI (Choisy-Le-Roi, France), Laétitia D'ALOIA-SCHWARTZENTRUBER (Bron, France)

14:30-14:50
Sustainability assessments for tunnels - where are we and what needs to be done?  ​​​​​​​
Markus THEWES (Bochum, Germany), Goetz VOLLMANN (Bochum, Germany)

14:50-15:10
The eco-design of the Toulouse metro Line C certified HQE Sustainable Infrastructures
Erwan CARFANTAN (Toulouse, France)

15:10-15:30
Underground infrastructures as laboratories for sustainability: a multi-standard reading of the Mont-Cenis Base Tunnel (Lyon–Turin)
Manuela ROCCA (Turin, Italy)

This article provides an in-depth analysis of the sustainability of underground infrastructure and highlights the need for assessment methods tailored to their specific characteristics. While existing tools such as HQE, ENVISION, and BREEAM address sustainability in a general way, they poorly account for the distinct features of underground structures, whether in terms of impacts or advantages. Underground infrastructure helps reduce land take, preserve ecological continuity, and improve urban resilience, in alignment with several Sustainable Development Goals (SDGs). It is also essential for managing natural hazards, mobility, storage, and climate change adaptation. The article distinguishes the functional dimension from construction related impacts. In both areas, it analyses the advantages and limitations of underground solutions, during both early-stage planning and project execution. Based on these specificities, requirements are defined for upstream and downstream project phases, combining traditional best practices with additional sustainability driven expectations: planning, stakeholder engagement, whole life costing, BIM, impact reduction, and environmental and social optimisation. Risk management—already central in underground works—can also support a sustainability-oriented approach: quantitative analysis can reduce overdesign and thus carbon impact, as demonstrated in fire safety design for metro systems. Similarly, accepting a higher level of settlement risk can influence construction methods and ground support design. This approach, balancing probabilistic risks with proven impacts, opens promising avenues that remain under exploration.  

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Sustainability is understood as a triad of economic, ecological, and social aspects that must be considered equally and given the same priority in evaluations. While it is increasingly becoming a dominant topic for construction in general, and for underground construction in particular, the issue of the so-called “carbon footprint” dominates all other discussions in the public perception. However, sustainability is actually much more than just balancing greenhouse gases and looking at the planning and construction period of a project. Underground infrastructure, with its service life often far exceeding 100 years and its undeniable effects on the surface provides assets far beyond the carbon footprint, which are currently underrepresented in assessment methods. With that being said: when two variants are compared, it is theoretically possible that the one with the higher CO2-emissions might be the more sustainable in the long run, if it provides a better performance regarding economic or social aspects. This article show how sustainability is currently assessed and, above all, where the weaknesses and problems of the available assessment algorithms lie. In addition, the aforementioned blueprint will be presented and an outline will be provided of the knowledge gaps that urgently need to be closed at the international level so that tunnel construction can continue to be carried out effectively.  

  

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The first metro line to be certified HQE Sustainable Infrastructures™ during the programming and design phases, the Line C project certification reflects a strong environmental commitment from the preliminary studies onward. Tisseo has thus chosen to pursue the HQE approach for its comprehensive methodology, which integrates all sustainable development challenges in a balanced manner: economic, social, and environmental. With over 60 Sustainable Development objectives and 200 concrete actions, the environmental ambition for the project's underground spaces is embedded in the DNA of Toulouse's new metro line. The purpose of this article is therefore to outline the essential prerequisites for successfully completing all stages of HQE Infrastructures Durables™ certification for a metro line. The final chapter presents some of the flagship initiatives implemented in Line C's underground spaces, made possible by the certification's ambitious goals. These include energy-saving measures, resource conservation, indoor air quality performance, and rigorous management of excavated soil.

  --- Underground infrastructures represent very valuable test benches for employing and developing multi-standard protocols to measure and improve the sustainability of projects and construction sites. The Mont-Cenis base tunnel project, the central structure of the Lyon-Turin line, which is a cross-border infrastructure and one of the main construction projects in Europe, is an emblematic case. From the design phase to the execution of the work, several recognised standards were used to organize and evaluate the environmental and societal performance of the project. Among them, the Envision protocols, which originated in North America, and HQE are being used with three objectives: to measure the overall sustainability of the project or specific operational construction sites, to guide the execution project phase of the construction sites and as a basis for scoring in the evaluation phase of the tenders. During the construction phase, for example, the Sustainable Construction Site Guideline, which in 2025 became a practice recognised by the UNI under the name UNI/PdR 172:2025, developed by a working group of the Italian Sustainable Infrastructure Association, has been integrated as an operational tool to supervise practices in the field, reduce nuisance for the local area and integrate social aspects. The joint application of these standards has made it possible to implement a coherent, measurable and innovative approach to sustainability. However, protocols and standards must always be customized. This is the case, for example, of the environmental indicators during the construction phase that were developed by TELT and which were the subject of a subsequent study with the CETU, or the project carbon footprint, for which TELT has developed a dynamic monitoring tool.  
12.10.2026
14:00 - 15:30
Room 0.5
Congress Conference
F. The future of underground infrastructures: flexibility, resilience and innovation
RESILIENCE AND ADAPTATION OF UNDERGROUND INFRASTRUCTURE TO CURRENT AND FUTURE NEEDS

Chairmen : Emmanuel HUMBERT (Chambery, France), Eric LECA (Paris, France)

14:00-14:10
Introduction

14:10-14:30
Geothermal energy in tunnels and stations: which the barriers and solutions for its implementation?
Lassana TRAORÉ (Bron, France)

14:30-14:50
Railway tunnel gauging: adaptation challenges and sustainable solutions for structures
Marina MACHADO (Saint-Denis, France)

14:50-15:10
Modernizing Historic Railway Tunnels: An Industrialized Approach to Under-Traffic Operations
Houda TADLAOUI (Saint-Denis, France)

15:10-15:30
Lyon (France) - Fire resistance analysis of the four existing metro lines.
Gaelle BRONN (Annecy, France)

Although studies show that tunnels and stations are underground structures with high geothermal potential, their development still remains marginal. Discussions with various specialists and stakeholders involved in geothermal projects for tunnels and stations in France have allowed to point out several issues mostly organisational aspects that complicate the implementation of geothermal energy in these structures. However, favourable outcomes can be achieved if all stakeholders in the geothermal energy chain are involved from the early stages of the project. --- In the face of road congestion and ecological imperatives, rail freight development is a priority. The National Rail Freight Development Strategy (SNDFF) aims to deploy, by 2030–2050, a network of rail highways to concentrate flows and strengthen rail competitiveness versus road transport. Existing tunnels, often over a century old, require substantial adaptation works to carry semi-trailers on wagons while maintaining operations. Several technical solutions are possible (partial or full vault widening, track lowering), adapted to each structure’s specifics (layout, condition, depth, prior works). These heavy, complex interventions on aging and sensitive structures, which must reconcile structural adaptation with continued operation, entail high costs and significant capacity impacts that discourage investment. To address these challenges, the Tunnels and Geotechnics Division of SNCF Réseau is conducting exploratory studies as part of the Ulysse Fret project, in cooperation with the Ministry of Transport and the 4F consortium (Fret Ferroviaire Français du Futur). A dedicated methodology has been developed to assess the impact of semi-trailers trucks on wagons in existing tunnel structures, identify priority zones for intervention, and propose a phased investment plan to ensure the technical and economic feasibility of the projects. The ultimate goal is to establish a master plan for the transport of semi-trailers that will provide a long-term vision for investment. --- The French railway network includes a vast heritage of old tunnels, with an average age of around 135 years. While these structures remain robust, they no longer meet the performance standards required for a modern and competitive rail freight system-particularly for accommodating LGP400-gauge freight trains operating on European corridors designated as rail freight highways. Conventional tunnel enlargement methods (widening, lowering the track bed, or both) are costly, disruptive, and operationally intensive. An industrialized alternative—using a sliding gantry—has been developed to minimize disruptions. This mobile structure isolates the work area while allowing trains to pass inside, enabling continuous rail operations during construction. The solution aims to reduce service interruptions while achieving the necessary infrastructure upgrades. This method, inspired by practices already implemented in Germany and Spain for tunnel widening projects, aims to increase work rates, lower costs, and minimize operational impact. This paper compares, for five tunnels on line 070 000, the costs, timelines and operational impacts of an industrialized method versus traditional tunnel enlargement methods, in order to quantify potential performance gains and assess the relevance of large-scale deployment across the national rail network. --- SYTRAL Mobilités is the transport authority for the city of Lyon and almost the entire Rhône department in France. SYTRAL Mobilités organizes the metro network, which consists of four lines (A, B, C, and D) with of 42 stations and 34.55 km of tracks. The structures of these four metro lines, built in the 1970s and 1980s, were not designed with fire resistance in mind. SYTRAL Mobilités wished to assess the fire resistance of its tunnel infrastructure in the event of a train fire. This paper presents the study carried out to determine the fire resistance of each homogeneous section of the metro network. After presenting the network, the methodology adopted to analyze the fire resistance of the existing tunnels is detailed. The first step was to gather detailed information on the structures from archives (plans, calculation notes), to select representative sections. Thermal and mechanical models were then developed for these sections. The results obtained indicate the fire resistance duration of the various sectors, enabling SYTRAL Mobilités to adapt its safety measures, particularly the management of roadways in the event of a fire. The calculations also provide the failure method for each homogeneous section and help identify the weaknesses of each type of structure under fire conditions. The diversity of structure types encountered (cut-and-cover, bored tunnel, tunnel boring machine, bridges, buildings, etc.) and the scale of this study provide a reference in the field of fire resistance analysis for existing structures.
12.10.2026
14:30 - 15:00
Agora
Lecture
LECTURE - EIFFAGE

LECTURE - EIFFAGE

Conjoncture et Perspectives économiques / Economic Environment and Outlook

Loïc THEVENOT, Director of the Major Underground Works Department

12.10.2026
15:30 - 16:30
COFFEE BREAK

COFFEE BREAK

12.10.2026
15:45 - 16:15
Agora
Lecture
LECTURE - EGIS

Lecture - EGIS

12.10.2026
15:50 - 16:20
e-poster station 1
Commented e-posters
COMMENTED E-POSTERS SESSION 2

15:50 -  15:58

The transformation of Paris’s underground car parks: Towards circular urban infrastructure

Youssef DIAB - Université Gustave Eiffel (Paris, France)

16:00 -  16:08

Innovation of TELT’s Constructive Geological Portal: Turning Data into knowledge 

Parisi - MARIA ELENA Telt (Turin, Italy)

16:10 -  16:18

Simplified numerical modelling of tunnel excavation using a TBM and its effects on piles: application to the TULIP project

Hadia ZAITER - Université De Lille, Imt Lille Douai, Université D’artois, Yncréa Hauts-De-France, Ulr 4515-Lgcge, Laboratoire De Génie Civil Et Géo-Environnement, F-59000 Lille, France (Villeneuve d'Ascq, France)

The transition to low-carbon and resilient cities requires a profound reassessment of urban infrastructure inherited from the 20th century. Among these, underground parking garages constitute a considerable built stock, designed for a mobility model that is now in decline. This article offers a systemic and interdisciplinary analysis of the repurposing of Parisian underground parking garages according to the principles of the circular economy. It draws on frameworks from urban engineering, ecological economics, and governance science to demonstrate that these infrastructures can become strategic hubs for the production, storage, and redistribution of resources (energy, materials, logistics, services). Based on technical analyses, feedback from several ongoing projects, and prospective scenarios, the article formulates recommendations for public decision-makers and urban operators. --- In the midst of work to build the Lyon-Turin Cross-Border Section, the new high-speed rail line that will connect France to Italy, TELT's Construction Geology Portal plays an important role. This portal, dedicated to managing technical data, has collected a vast amount of information over time. The first data dates to feasibility studies in the early 1990s. Today, with construction sites operational, data collection continues seamlessly with an ever-increasing amount of information. The integration of new technologies and the constant updating of TELT's Constructive Geology Portal, organized according to the logic of Work Breakdown Structure (WBS), are the key elements to ensure that all information can be accessed and used in real time. Recently, the types of data collected have increased to include pre-classification of excavated material, a preliminary step to its classification for use. This increase in information has made it clear that content needs to be made more usable and understandable for technical users. To meet this need, advanced data representation and aggregation features have been introduced. These include static and dynamic graphics dedicated to specific topics, which have significantly improved interaction with the portal. These visualizations facilitate data analysis and interpretation, making the process more intuitive and immediate. The evolution of the portal also involved optimizing the underlying architecture to ensure high performance and real-time updates. This continuous improvement ensures that TELT's Construction Geology Portal remains a state-of-the-art tool capable of effectively supporting the Lyon-Turin works and responding to the growing technical needs of the project. --- Numerical modelling of tunnel excavation using tunnel boring machines (TBMs) remains a challenge due to the complexity of the phenomena involved and the large number of parameters to be taken into account. Although widely used, conventional approaches have limitations in terms of accuracy and parameter calibration, and their implementation often remains difficult. In this context, the TULIP project (Tunnelling and Limitation of Impacts on Piles), carried out between 2019 and 2022 in Aulnay-sous-Bois by Société du Grand Paris in collaboration with Université Gustave Eiffel, ENTPE and the French Centre for Tunnel Studies, enabled full-scale investigation of the effects of an Earth Pressure Balance TBM passing near three instrumented piles. The experimental results obtained provide a valuable basis for the development and validation of new simulation tools. To address the identified challenges, a simplified and automated numerical modelling method has been developed. This approach is based on the combined application of stress relaxation forces due to excavation and grout injection pressure, directly applied in the annular gap between the tunnel lining and the surrounding ground. Integrated into a three-dimensional finite element model, the method makes it possible to reproduce, in a simplified but realistic way, the complex interactions between the ground, the TBM, the grout and nearby structures. Applied to the TULIP case study, the method satisfactorily reproduces the measured ground and pile displacements, while providing good accuracy, numerical robustness and a level of implementation suited to engineering practice. This paper will highlight the 3D modelling results, the influence of injection parameters, TBM advance rate, and the evolution of grout rheology, while underlining the relevance of this method as a practical alternative to conventional approaches. Keywords: Tunnel Boring Machine (TBM), numerical modelling, simplified method, deep foundations, soil–structure interaction, annular grout
12.10.2026
15:50 - 16:20
e-poster station 2
Commented e-posters
COMMENTED E-POSTERS SESSION 2

15:50 -  15:58

Automation of the Time Adjustment Mechanism: An asset for construction phasing and contractual management of a project modification on the TELT CO6-7 Worksite

Narjes OUALI - Systra (Saint jean de maurienne, France)

16:00 -  16:08

From data analysis to the improvement of an earth pressure balance shield's performance

Nour EL SOUWAISSI - Eiffage Génie Civil (Velizy Villacoublay, France)

 

Schedule management is a critical challenge for complex infrastructure projects. The TELT project (Tunnel Euralpin Lyon–Turin) involves building a 57.5 km cross-border base tunnel between France and Italy, a central link of the new high-speed line. Worksites 6 and 7 (CO6-7) cover 50 km of tunnel excavation, including 23 km carried out using three tunnel boring machines (TBMs) and conventional methods for the base tunnel. For CO6-7, the Vinci-WeBuild consortium proposed a modification to optimise the phasing and timelines for constructing the La Praz safety site (CO6) and launching two TBMs in this area. This Modification Sheet (FM) notably provides for the creation of two logistics structures (log 5 and log 6) to increase the number of excavation fronts, the simultaneous assembly of the two TBMs in the technical cavern, their 90° rotation and lateral shift to avoid building temporary assembly caverns, and the continuation of the CO7 TBM excavation into CO6 to remove the need for a disassembly cavern. These measures strengthen the phasing while maintaining the contractual final milestone dates. This context highlighted the need for a robust and flexible contractual tool to monitor milestones: the Time Adjustment Mechanism. Monitoring tools have been implemented to integrate geological hazards and phasing changes on a daily basis, allowing critical paths to be recalculated and the associated contractual milestones to be adjusted.
12.10.2026
15:50 - 16:20
e-poster station 3
Commented e-posters
COMMENTED E-POSTERS SESSION 2

15:50 -  15:58

Moriez Tunnel: Financial, Organisational and Technical Challenges

Grégoire DAMIEN - Spie Batignolles Génie Civil (Nanterre, France)

Located between the municipalities of Moriez and Saint-André-les-Alpes (04), the Moriez tunnel, commissioned in 1880, is undergoing a major renovation operation aimed at restoring rail traffic between Digne-les-Bains and Nice by the end of 2026. The tunnel, 1.2 km long, has been the subject of works carried out by the Spie Batignolles Génie Civil - NOUVETRA joint venture, divided into two lots. The first lot aims to reinforce and secure the tunnel. The critical zone at chainage PM 400, marked by a collapse in 2019 and backfilled in 2021, is being re-excavated, followed by the installation of heavy support and then a cast-in-place reinforced concrete lining. The same principle is applied at PM 1100, without a re-excavation phase, with gradual demolition of the masonry after prior rock bolting. For areas with high convergence of the sidewalls, the reinforcement includes rock bolting and a fibre-reinforced sprayed concrete shell. In less sensitive areas, rock bolts alone are sufficient to stabilise the sidewalls. The second lot concerns the restoration of the masonry lining. It includes surface cleaning followed by repointing with mortar. Grouting operations, used to fill voids and restore contact between the masonry and the surrounding ground, as well as regeneration injections within the thickness of the lining, help to restore the structural integrity of the facing. This project has made it possible to sustainably secure the structure and ensure the long-term durability of the railway line while respecting the technical constraints of a historic tunnel.
12.10.2026
16:30 - 18:00
Room 0.4
Congress Conference
A. Sustainable solutions to environmental challenges
MANAGEMENT OF EXCAVATED MATERIAL

Chairmen : Nataliya DIAS (Chatenay-Malabry, France), Emmanuel HUMBERT (Chambery, France)

16:30-16:40
Introduction

16:40-17:00
Assessment of the environmental impacts associated with the use of excavated materials from underground structures? Application to the case of the base tunnel of the cross-border section of the Lyon-Turin line 
Agnès CHERREY (Bron, France)

17:00-17:20
The Lyon-Turin cross-border section: An innovative example of circular economy for excavated materials 
Rocca MANUELA (Turin, Italy)

17:20-17:40
The French spoil valorisation lot of the Montcenis base tunnel, a project within the project: commissioning and first feedback 
Lione STEFANO (Turin, Italy)

17:40-18:00
Management and use of excavated materials of the CERN’s Future  Circular Collider (FCC)
Laétitia D'ALOIA-SCHWARTZENTRUBER (Bron, France)

The Euralpin Lyon Turin Tunnel (TELT) company is committed to optimising the management of excavated materials from various civil engineering sites for the construction of the cross-border section of the Lyon-Turin base tunnel. Although space is limited, TELT has planned a substantial logistics operation to reuse the excavated material on site, in concrete aggregates and backfill, supplemented by the use of rail to transport surplus material to distant quarries. These circular economy practices should help to limit environmental impacts such as the depletion of natural and energy resources, climate change, land use and land use change. The aim of the study is to assess the potential environmental impacts of reusing excavated material from the Lyon-Turin tunnel and to compare them with sourcing aggregate from quarries. --- As part of the project to build the cross-border section of the new Lyon-Turin railway line, TELT is implementing a sustainable strategy for the management of the excavated materials resulting from the excavation of the base tunnel. While the construction of the base tunnel will require the excavation of a total of 37 million tonnes of material over a period of 10 years, including 30 million tonnes on the French side and 7 million tonnes on the Italian side, most of this material (> 50%) will be used for the project. This is a remarkable goal that can be even more ambitious in the future. To achieve this, TELT has set itself even greater environmental challenges: ensure a binational balance and management in the use of materials. In 2023, with the signing of an agreement, the two governments took a political decision to go beyond the border and make the Lyon-Turin project a pilot experiment in the binational circular economy, with the aim of achieving a global balance - with a zero-waste trend - as a concrete contribution to the European Green Deal. A targeted implementation mechanism has been developed by TELT, under the auspices of the intergovernmental committee, to put this agreement into practice: an operational protocol will regulate the process for using surplus CL1 from Italian construction sites on French sites, and vice versa for using surplus French CL2 on Italian sites. This will enable TELT to optimize the materials balance of the single French-Italian construction site. --- Spoil management is one of the most complex challenges in the construction of the cross-border section of the Lyon–Turin railway line. The project involves the excavation of a base tunnel more than 57 km long through the Alps, including 45 km on French territory, with an estimated production of approximately 23 million tons of excavated material. The efficient, safe and sustainable management of these materials is a key factor in the success of the project. Sustainable development objectives are implemented through concrete actions, with more than 50% of the excavated materials intended for reuse in environmental rehabilitation works, aggregate production for concrete and the construction of embankments for the project infrastructure. Extending over more than 30 km between Saint-Jean-de-Maurienne and Villarodin-Bourget/Modane, this project is part of a complex system of construction sites, requiring the management of numerous interfaces and continuous adaptation to rescheduling linked to excavation progress. Having now exceeded two million tons of processed materials, this paper presents the key design principles of the integrated spoil management system on the French side, together with initial feedback highlighting both the opportunities and the challenges encountered at the interface between technological innovation, safety and environmental and territorial sustainability. --- Building the underground infrastructures of the CERN's Future Circular Collider (FCC) in the Geneva basin beneath the Swiss and French territories, will produce approximately 6.3 million cubic meters of excavated materials (in-situ volume), mainly molasse (95%), a highly heterogeneous sedimentary rock. The feasibility study for this research infrastructure was co-financed by the European Community (EC) as part of the H2020 program. The study focused in particular on geological and environmental conditions, as well as technically feasible concepts for infrastructure, civil engineering, and detectors. With regard to civil engineering and in accordance with the circular economy principle, the study aimed to develop approaches for the reuse and recovery of excavated materials. Uses have been identified, such as the production of fertile soil, the benefits of which were highlighted by the international challenge “Mining the future”. Beyond the economic and environmental aspects, several issues were also addressed in the deliverable: “Strategy for the management and use of excavated materials” This document, produced by a dedicated working group, describes a possible strategy based on the current state of knowledge. Anticipation, territorial analysis, compliance with French and Swiss regulations, characterization, and sorting are some of the key points for successful management to help ensure the technical and economic feasibility of the project and strengthen its societal acceptability. If the decision to build the FCC is made, the strategy will be refined as the project progresses and supplemented by operational documents.
12.10.2026
16:30 - 18:00
Room 0.5
Congress Conference
B. Technological and digital innovations in underground work
FEEDBACK FROM PROJECTS (Part 1)

Chairmen : Morgane BERTRAND (La Motte-Servolex, France), François LAIGLE (Lyon, France)

16:30-16:40
Introduction

16:40-17:00
Design of the interconnection between Line 15 East and the extension of Line 1 
Omar MORENO REGAN (Paris, France), Rémi HURE (Paris, France)

17:00-17:20
Technological and digital innovations in underground construction: The case of the Chiltern Tunnels (UK)
Karine BEN KEMOUN (Guyancourt, France)

17:20-17:40
Innovative Waterproofing Strategy under Extreme Alpine Conditions: TELT deep-depth durability protocol
Arnaud TAILLANDIER (Chambery, France)

17:40-18:00
Evolution of the AFTES recommendation on the design and dimensioning of shotcrete for tunnel support. 
Christophe JASSIONNESSE (Nanterre, France)

This paper presents the design studies for the interconnection shaft between lines 15 and the future extension of line 1, located in Val de Fontenay station on line 15 East of the Grand Paris Express. This context led to the development of a complex structure that enables the two lines to cross underground, under significant geometric and urban constraints, meeting both the functional and technical requirements of the project. The structure's atypical geometry stems from the numerous constraints associated with the site (proximity to the A86 motorway and the RER E regional express railway) and the requirements of the SGP. To this end, a diaphragm wall enclosure was designed, into which a second, deeper wall was inserted, creating a framework for the M1 tunnel to pass through. In addition, the structure is divided into two areas built under separate contracts, requiring specific phasing. The design was guided by two main uses: to serve as a launch shaft for the TBM in its Line 15 section and to enable interconnection with Line 1. During the tendering process, the SGP's programme changed several times, leading to a review of the design at each iteration. The structural design was first carried out using conventional 1D approaches with subgrade model method, then using more complex 3D models based on plates supported by elastoplastic springs. All calculations were performed using in-house ‘Pythagore’ finite element software. --- As part of the HS2 project in the UK, the excavation of the 32 km Chiltern Tunnels represented a major technical challenge and a unique opportunity to advance innovation in the field of tunnel boring machines. Bouygues Travaux Publics deployed robotic solutions to reduce operator exposure to high-risk areas, including the KROKODYL robotic arm for the automatic removal of wedge spacers and the ATLAS system for automated ring assembly. Automated management of pumps and bypasses optimised hydraulic control, while the new digital interface of the Thrust Centre facilitated automatic TBM guidance via PYXIS and enabled the implementation of continuous excavation, allowing rings to be installed without interruption. A third recycled water supply line and the use of an inert polymer, which processed 3 million m³ of spoil without chemicals, reduced water and energy consumption, carbon emissions and transport, while improving operator safety. Thanks to this combination of digital, robotic and environmental innovations, the Chiltern Tunnels project showcases a new generation of smarter, safer and more sustainable underground construction. --- TELT (Tunnel Euralpin Lyon–Turin) project is a major binational rail tunnel connecting France and Italy through the Alps. It faces unprecedented waterproofing challenges due to its extreme geological conditions, with rock overburdens exceeding 2,000 meters, groundwater temperatures above 50°C, and chemically aggressive environments. In these conditions, achieving a 120-year design life requires exceptional material performance and durability verification. To meet these demands, TELT specified a 3 mm transparent PVC-P geomembrane, exceeding the conventional 2 mm standard used in France, and tested it through a dedicated Deep-Depth Durability Protocol. The protocol was developed and run in collaboration with CETU, CEREMA, INRAE, and geomembrane manufacturers Mapei, Renolit, and Soprema ; reproduces severe thermal and chemical ageing through prolonged immersion in controlled baths, to assess the long-term resistance of these geomembranes under simulated deep-tunnel conditions. During the 24-month accelerated aging, the geomembrane samples were periodically tested for tensile strength, puncture resistance, and plasticizer retention under acidic, basic, and high-temperature exposure. Results demonstrated stable mechanical performance and limited degradation, confirming the geomembranes’ suitability for deep alpine tunnelling. This proactive, result-driven approach highlights how early collaboration among clients, researchers, and manufacturers can drive innovation and mitigate long-term risks. The Deep-Depth Durability Protocol establishes a reproducible testing framework adaptable to other large-scale tunnelling projects, providing a scientific basis for developing robust, evidence-based waterproofing strategies in extreme underground environments. --- The upcoming updates to the AFTES recommendations introduce significant advancements in the design and structural sizing of shotcrete used for tunnel support. These updates include a more precise definition of the three key functions expected of shotcrete, improved consideration of its early-age mechanical behavior, and a harmonization of calculation methods with existing AFTES guidelines on rock bolt design and shotcrete intended for permanent use in underground structures. Additionally, the recommendations now incorporate Ultimate Limit State (ULS) design principles for fiber-reinforced shotcrete—whether using steel or synthetic fibers—and reflect the latest developments in Eurocode 2 in this area.
12.10.2026
16:30 - 17:30
Agora
European Session
A. Sustainable solutions to environmental challenges
EUROPEAN SESSION: PROJECTS & PERSPECTIVES PART 1

Chairman: Eric LECA - President of the EUTF (Paris, France)

16:30 - 16:40
Introduction
Eric LECA - President of the EUTF (Paris, France)

16:40 - 16:50
BELGIUM
Bart DEPAUW (Zaventem, Belgium)

16:50 - 17:00
GERMANY
Roland LEUCKER (Cologne, Germany)

17:00 - 17:10
SWITZERLAND
Davide FABBRI (Bellinzona-Giubiasco, Switzerland)

17:10 - 17:30
Discussion

12.10.2026
18:00 - 20:00
OPENING COCKTAIL RECEPTION

OPENING COCKTAIL RECEPTION