This two-part session provides a comprehensive overview of precast concrete segmental tunnel lining systems, from design through production and construction. Presenters from industry, academia, and practice will explore critical topics including structural design, concrete technologies, fiber reinforcement, accessories, gaskets, formwork, precast production, contractor quality control, and durability-based design. Case studies and innovations from major international projects will highlight current challenges and emerging solutions. The session is designed to benefit designers, engineers, contractors, producers, owners, and young professionals engaged in underground infrastructure.
Learning Objectives:
(1) Discuss the structural design principles of precast segmental tunnel linings, including load cases, limit states, and geometric optimization;
(2) Analyze how concrete material selection, mix design, early-age hydration, curing regimes and QA/QC practices influence the early-age and long-term performance, durability, and sustainability of precast tunnel segment;
(3) Assess how fiber reinforcement enhances structural performance, crack control, and production efficiency in precast tunnel segments;
(4) Review the evolution of tunnel segment accessories and evaluate current innovations in connector technologies that enhance assembly efficiency, structural integrity, and durability in modern segmental tunnel linings;
(5) Evaluate the evolution of sealing gasket technologies in segmental tunnel linings, and assess how innovations improve watertightness, installation efficiency, and long-term durability in TBM-driven tunnels.
This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.
Design Fundamentals of Precast Segmental Tunnel Linings
Presented By: Verya Nasri
Affiliation: AECOM
Description: This presentation outlines the comprehensive design framework for precast segmental tunnel linings, from geometric configuration through all structural limit states. It covers the full spectrum of design stages—production, construction, and final service—and details the associated load cases, design checks, and analytical methods, including finite element approaches. Particular emphasis is placed on geometry optimization, segment handling, construction loading, and the structural response to thrust jacks, ground pressures, seismic events, and fire. The session also addresses serviceability limit state design, segment durability, reinforcement detailing, and sustainability considerations such as embodied carbon. Together, these principles establish a technically rigorous and adaptable methodology for modern tunnel lining design worldwide.
Concrete Technologies for Precast Tunnel Segments
Presented By: Barzin Mobasher
Affiliation: Arizona State University
Description: This presentation explores critical aspects of precast segmental tunnel lining systems, focusing on concrete materials, mix design, and quality control. It highlights how early-age hydration, curing regimes, and the use of supplementary cementitious materials influence durability, dimensional precision, and long-term performance. Case studies from underground and tunneling projects are used to illustrate practical production challenges, QC/QA strategies, and adaptation to various curing conditions. The discussion also addresses material technologies and plant production principles that enable high-performance, watertight, and sustainable segment manufacturing. These insights support the development of resilient tunnel linings aligned with global carbon reduction and sustainability goals.
Fiber Reinforcement in Precast Tunnel Segments
Presented By: Benoit De Rivaz
Affiliation: Bekaert
Description: This presentation focuses on the use of fiber reinforcement in precast segmental tunnel linings and its growing role in modern tunnel infrastructure. It outlines key design considerations, fiber types, dosage optimization, and structural performance, along with guidance on testing and quality control throughout the segment lifecycle. Testing is addressed in two stages: initial material qualification through trial batching, and routine production testing to verify consistency and compliance with design intent. Practical case studies are used to illustrate how fiber reinforcement improves crack control, durability, production efficiency, and safety. Together, these insights demonstrate how fiber technology supports more reliable and efficient segmental tunnel lining systems.
The Evolution of Tunnel Segment Accessories
Presented By: Christophe Delus
Affiliation: Optimas Solutions
Description: Tunnel segment connectors—critical for joining segments within a ring and between rings—have evolved alongside advancements in mechanized tunneling and the widespread adoption of one-pass precast segmental linings. Historically, curved steel ‘banana’ bolts dominated the field. Today, industry preferences are shifting toward high-performance polymer dowels, straight bolts with polymer sockets, and guiding rods that streamline assembly and enhance durability. Simultaneously, innovations in tunnel boring machines (TBMs)—particularly the adoption of vacuum erectors—have accelerated the global acceptance of polymer-based grout sockets. This presentation traces the historical development of tunnel segment accessories, highlights current trends in connector technologies, and explores the state-of-the-art innovations poised to shape the future of tunneling worldwide.
Sealing Gaskets for Tunnel Segment Linings – 55 Years of Development
Presented By: Andreas Diener
Affiliation: Theodor Cordes Gmbh & Co.Kg
Description: In TBM tunnel construction, gaskets are critical for ensuring watertightness at the joints between concrete segments, preventing groundwater ingress and protecting tunnel durability. This presentation traces the 55-year development of sealing gaskets used in precast segmental tunnel linings, beginning with their first application in the Elbe River Crossing tunnels in Hamburg in the late 1960s. The transition in material technology—from CR to EPDM rubber—and the evolution from simple comb-shaped elastomer profiles to advanced hollow chamber and double-decker designs have enabled higher sealing performance, particularly for large-diameter and high-pressure tunnels. Recent innovations include anchored (cast-in) gasket systems, which offer improved bonding, reduced installation time, and safer, solvent-free working conditions. Case studies such as the Brenner Base Tunnel and upcoming “green” infrastructure projects illustrate the growing role of gasket technology in sustainable and resilient tunnel systems.