What is TBM Tunnelling?
TBM tunnelling is a mechanised construction method in which a Tunnel Boring Machine (TBM) excavates soil or rock while supporting the excavation face and progressively constructing the tunnel lining. Compared with conventional tunnelling methods, TBM tunnelling provides a high level of mechanisation and automation and is widely used for urban rail, transport, hydropower, utility and other long underground infrastructure projects.
Depending on the geological conditions and project requirements, different TBM technologies may be employed, including EPB TBMs (Earth Pressure Balance TBMs) and Slurry TBMs (Slurry Shield TBMs, typically using bentonite slurry). Successful TBM tunnelling requires more than machine performance alone; it depends on the precise interaction between ground conditions, materials, equipment and the overall construction process.
Every Metre of Advance Matters
Mechanised tunnelling is a continuous process where productivity, cost and safety are closely connected to the stability of the entire tunnelling system.
Ground conditions may range from sand, gravel and cohesive soils to mixed ground. Variations in water pressure, permeability, friction, abrasion, adhesion and clogging can have a direct impact on TBM operation.
The key question is therefore not simply:
“Can the TBM excavate?”
but rather:
How can stable, safe and efficient tunnelling be maintained as underground conditions continuously change?
Each geological condition – A different requirement
There is no single soil conditioning solution that is suitable for every project.
For EPB TBMs, the excavated material is used as the pressure medium at the tunnel face. Therefore, the properties of the excavated material must be appropriately controlled to ensure effective transport, reduce friction and support stable excavation.
By contrast, Slurry TBMs use bentonite slurry and therefore require different considerations, including slurry stability, adhesion and clogging control, as well as separation efficiency.
The combination of geological conditions, TBM type and operating conditions requires the solution to be tailored to the specific requirements of each project rather than based on a fixed formulation.
Advanced integrated solutions for for TBM tunnelling
Rather than simply supplying specialised materials, MC Underground (MCU) combines in-depth underground expertise, advanced technologies and integrated solutions to meet the demanding requirements of mechanised TBM tunnelling.
MCU is a specialised business unit within MC-Bauchemie, bringing together experienced international specialists with expertise in TBM tunnelling, conventional tunnelling and mining. From technical consultancy and solution selection to on-site implementation, MCU supports projects with in-depth technical expertise and extensive practical experience.
MCU develops specialised technologies to address practical challenges in TBM operation – from soil conditioning and control of excavated material properties to sealing, lubrication and grouting. Technologies such as MC-StartupFoam®, MC-RheoSand®, MC-RheoClay® and MC-SolidFoam® provide solutions tailored to different geological conditions and tunnelling requirements.
Rather than focusing on individual products, MCU views TBM tunnelling as an integrated operating system.
Its range of solutions covers critical stages of the tunnelling process, while the coordinated interaction between these solutions helps improve the stability and efficiency of the overall construction process, rather than optimising each stage in isolation.
Every TBM project presents different challenges in terms of geological conditions, TBM type, operating conditions and technical requirements. Therefore, MCU focuses on solutions that are selected and adjusted to the specific conditions of each project, rather than applying a fixed solution across different sites.
MCU’s value extends beyond technologies and materials. Its international team of experts supports customers throughout the project – from technical consultancy, solution selection and training through to direct on-site implementation.
Soil conditioning
Soil Conditioning & Ground Stabilisation is one of the key initial steps in EPB TBM tunnelling. Specialised foam and polymer systems help modify the flow properties of excavated material, reduce internal friction and facilitate efficient excavation and muck transport.
MCU provides:
- Clay & Sand: Specialised foam,anti-adhesion agents for clay, structuring and water-retaining polymers ,…
- Fault zones, EPB in gravel or hard rock
- Startup solutions
Solutions are tailored to specific geological conditions, ranging from sand and clay to complex and high-risk ground environments.
Greases & Tail sealants
Under high-pressure underground conditions, protecting critical TBM components against the ingress of water and fine particles is essential for equipment reliability.
MCU provides:
- Main bearing sealing grease
- Main bearing greases
- Tail sealants
- Tail sealants first fill
- Press plate pumps
The solutions are designed to support effective sealing, protect equipment and maintain stable operation under demanding tunnelling conditions.
Annulus grouts
The annular gap between the tunnel lining segments and the surrounding ground needs to be filled quickly, uniformly and in a controlled manner as the TBM advances.
MCU provides:
- Superplasticisers
- Activators
- Special systems
- Cementitious and and Cement-free one-component (1K) and two-component (2K) grout systems
Annulus grouts play a critical role in limiting ground settlement, ensuring early and uniform load transfer, and contributing to the stability of the tunnel structure.
Precast tunnel lining components & segments
Tunnel lining segments must meet multiple requirements simultaneously, including strength, resistance to TBM jacking forces, durability and surface quality.
MCU provides:
- Admixtures & Additives
- Fibres
- Release agents & Curing agents
- Concrete repair & Cosmetics
The objective is to produce tunnel lining segments capable of withstanding high TBM jacking forces during construction, while ensuring long-term durability and optimum surface quality.
Injection & technical treatment solutions
Injection solutions help control water, stabilize ground, fill voids and address technical challenges arising during construction, contributing to safe and stable TBM tunnelling.
MCU provides:
- Joint sealing & Water control
- Structural filling & Sealing
- Soil stabilisation & Void filling
- Waterstop systems
The solutions are selected according to the actual site conditions and technical requirements of each project, enabling flexible and effective treatment throughout underground construction.
Innovative technologies for TBM tunnelling
MC Underground (MCU) continuously develops advanced technologies for TBM tunnelling, supporting stable operation, efficient resource use and adaptability to challenging geological conditions.
Next-generation soil conditioning solutions
- Technologies including MC-StartupFoam®, MC-SolidFoam®, MC-RheoClay®, MC-RheoSand® and MC-ArtSoil® help optimise the properties of excavated material, reduce water consumption and expand treatment capabilities across a wide range of geological conditions.
Specialised grouting technology
- MC-DrainGrout® expands the range of solutions for annulus grouts, addressing specific technical requirements in TBM tunnelling.
Sustainable & Environmentally responsible construction
- Plant-based soil conditioning foams, TBM tail sealants, greases and excavated material treatment technologies help reduce environmental impact and improve resource efficiency.
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