Sofrasar Tunnel Solutions

Supporting tunnel infrastructure teams with industry knowledge, design and engineering services, technical expertise and fastening solutions for over 25 years.
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ENGINEERING DESIGN SUPPORT

Make the best tunnel fastener decisions with expert design and engineering service assistance, finite elements analysis and project-specific technical support.

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RESPONSIVE AND EFFICIENT SHIPPING

Get the right solutions delivered at the right time to meet the specialized needs of your tunnel construction project—anywhere across the globe

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QUALITY
CONTROL

Know you have the highest quality parts as a result of our rigorous standards, zero defect culture, leading certifications and registrations.

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VALIDATION AND TESTING

Confirm the mechanical resistance of each system before you implement it with our full range of testing tools available at our laboratories

An assortment of different bolts and sofrasar tunnel parts

BOLTING SYSTEMS

Bolting systems are used for the assembly of concrete segments, rail fixings and belt conveyors. Our range of structural bolt systems can support tensile stress from 70 to 400 kN. Metallic inserts are made out of stainless steel, either 316L or a different grade as chosen through our design and engineering services. We offer various steel grade bolt options including ASTM A325 and 10.9, as well as zinc coated, hot dip galvanized or plastic coated.

DOWEL SYSTEMS

Fixating the rings through thermoplastic dowels can enable a quick and secure installation in tight global tolerances while providing stability of the rings as a result of ground or grout injection pressure.

CENTERING SYSTEMS AND SHEAR DOWELS

Centering systems and shear dowels that speed and simplify installation of concrete segments and enable optimum control of the shearing stress up to 500 kN. We offer a large range of dimensions and thermoplastic qualities to find the most appropriate deflection curves for your application.

GROUT-LIFT SOCKETS

A large range of grout and lift-sockets provide a tightness cap up to 40 bars and a breaking tensile stress up to 600 kN.

GUIDING RODS AND PACKERS

These simple and cost-effective products control the position between the concrete segments, providing a good shear resistance and full control of tight tolerances and slip hazards.

PRECAST ACCESSORIES AND SECURITY SYSTEMS

Our wide range of systems include:

  • Plastic and metallic inserts for the installation of electrical equipment
  • Fire protection products
  • RFID-based product traceability
  • Geothermal energy in tunneling

FINITE ELEMENTS ANALYSIS

With a large range of grout and lift-sockets, we can assist your design stage by undertaking finite elements analysis at our laboratories using specialized testing and software.

TUNNEL FASTENERS FAQS

Tunnel fasteners are specialized fastening systems used in tunnel construction to secure concrete segments, rail systems, and structural components. They are engineered to withstand high tensile loads, shear forces, ground pressure, and environmental stress over long service lifecycles.

Optimas provides bolting systems, dowel systems, centering systems, shear dowels, grout-lift sockets, guiding rods, packers, and precast accessories. These systems are designed to support tunnel segment assembly, alignment, load transfer, and structural stability.

Bolting systems are used to assemble concrete tunnel segments, rail fixings, and conveyor systems. Structural bolt systems can support tensile stresses from 70 to 400 kN and are available in various steel grades and coatings to meet performance and environmental requirements.

Dowel systems fix tunnel rings in place using thermoplastic dowels that enable fast installation while maintaining tight tolerances. They provide stability against ground movement and grout injection pressure during and after tunnel segment installation.

Centering systems and shear dowels help align concrete segments and control shear stress, supporting loads up to 500 kN. They simplify installation and help maintain structural integrity by controlling deflection and segment positioning.

Grout-lift sockets are used to lift and seal tunnel segments during installation. They can provide tightness up to 40 bar and tensile breaking loads up to 600 kN, supporting safe handling and structural sealing during tunnel construction.

Guiding rods and packers control segment positioning, shear resistance, and tolerance alignment between concrete segments. They reduce slip hazards and help ensure accurate installation in tight geometric tolerances.

Tunnel fasteners can be manufactured from stainless steel, structural steel grades such as ASTM A325 and 10.9, and coated with zinc, hot-dip galvanization, or plastic coatings. Material and finish selection depend on load, corrosion exposure, and project requirements.

Tunnel fastener systems can be validated through mechanical testing and finite element analysis to confirm load resistance, deflection behavior, and system performance before implementation. Validation ensures reliability under real-world tunnel conditions.

Engineering support helps ensure fastening systems are correctly specified for ground conditions, structural loads, and installation constraints. Design services and analysis reduce risk, improve safety, and optimize performance throughout the tunnel lifecycle.

Tunnel fastening systems are engineered to support a wide range of structural loads depending on application and system design. Typical solutions support tensile loads from 70 to 400 kN, shear forces up to 500 kN, and breaking tensile stresses up to 600 kN for specific components such as grout-lift sockets.

Tunnel fasteners are validated through mechanical testing and laboratory-based analysis to confirm tensile strength, shear resistance, deflection behavior, and system durability. Testing may be supported by finite element analysis to simulate real-world tunnel loading conditions before deployment.

Tunnel fastening systems are designed to meet applicable structural, material, and quality standards depending on the project and region. Common specifications include structural steel grades such as ASTM A325 and metric grades like 10.9, along with quality systems supported by certified manufacturing and testing processes.

RELATED LINKS

Explore our Tunnel Solutions

> DOWNLOAD BROCHURE

How to Find the Optimal Fixing Design to Meet All Tunnel Project Requirements

> READ ARTICLE

Tunneling Project Benefits from Innovative Fasteners

> READ CASE STUDY

In the beginning we were quite skeptical about working with dowels in circumferential joints. However, after the success in the Crossrail project, plastic dowels have become an alternative to the classic bolt system for our contractors.

– Customer Tunnel Lead

The Components of Unrivaled Success

To better serve you, we have tunnel solutions experts in Italy, Spain, Japan, Russia, Hong-Kong, India, Singapore, Oceania, South/Latin America and North America.

Sofrasar Tunnel Products

FRANCE

4 rue Robert Pax
57910 HAMBACH – France

T +33 (0) 3 87 98 90 35

CONTACT US

Optimas Tunnel Division

Representatives

HONG KONG

Merman Technology Company Ltd

T +852 (0) 2581 2660

INDIA

Modern International

T +91 (0) 11470 86481

ITALY

SMAAC

T +39 (0) 02 76110330

JAPAN

AJUMO

T +49 (0) 40 600 195 0

CHINA

Christophe Zhang

T +33 (0) 6 86 54 79 53

TURKEY

Ertunnel

T +90 (0) 312 219 40 47

SPAIN, PORTUGAL

ABYO TM

T +34 (0) 619 20 70 26

SINGAPORE & OCEANIA

Design & Technic Pte Ltd (DTS)

T +65 (0) 9770 0488

IBERO AMERICA

ABYO TM

T +55 (11) 97609-3682

EGYPT

ACo Expertise

T +33 6 38 73 85 25

USA & NORTH AMERICA

David R. Klug & Associates, Inc.

T (+1) 724 942 4670

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