What is a tunnel boring machine?

A tunnel boring machine is a machine specialized in tunnel excavation. Also known as TBM (Tunnel Boring Machine)The TBM is used for subway excavations in infrastructure projects, such as transportation, sanitation and mining networks. TBMs allow advancing in the ground while minimizing surface disturbance, which is essential in urban environments and in projects that seek to reduce environmental impact.

Operation of a Tunnel Boring Machine

The operation of a tunnel boring machine (TBM) is based on a rotary cutting system on the head, which shreds the soil and extracts the material as it moves forward. This equipment is capable of digging through a wide variety of terrains, from solid rock to soft soils, adapting its mechanism to work in specific conditions.

Main components of a tunnel boring machine

A tunnel boring machine has different sections, each with specific functions for the excavation and construction of the tunnel:

• Cutting headEquipped with discs or cutting tools, it is the front part that digs and breaks up the soil.
• ShieldProtects the TBM structure and stabilizes the ground around the tunnel during the excavation process.
• Transportation systemThe excavated material is collected and transported out of the tunnel by means of belts or augers.
• Support ringsAdvanced tunnel boring machines install concrete segments or rings as they excavate, ensuring tunnel stability.

Excavation process

1. Ground Excavation and FragmentationThe head rotates and cuts the soil, fragmenting the material, which is then transported to the rear.
2. Material ExtractionThe excavated remains are moved by internal conveyor systems, such as belts, and ejected from the tunnel.
3. Siding InstallationAs the TBM advances, it places support rings on the tunnel walls to reinforce the tunnel structure.

Types of tunnel boring machines

There are several types of tunnel boring machines, designed to adapt to different ground conditions and project needs.

Earth pressure tunnel boring machine (EPB)

The Earth Pressure Balance (EPB) TBM is ideal for soft and water bearing ground. It maintains pressure at the excavation face, preventing landslides and controlling pressure in unstable ground. This machine is particularly useful in urban areas where it is important to reduce the risk of surface settlement.

Slurry shield tunnel boring machine

This type of TBM uses slurry to stabilize the excavation face and is suitable for sandy or water-logged terrain. The slurry helps to maintain stability, preventing collapse in complex terrain.

Hard rock tunnel boring machine

Designed specifically for excavating in solid rock terrain, this type of TBM employs cutting discs that fragment the rock. As it advances, the hard rock TBM extracts large amounts of solid material and requires great power.

Applications of tunnel boring machines in construction projects

Tunnel boring machines are essential tools in a variety of subway construction and infrastructure projects. Their use covers a wide range of applications, from the construction of sewage networks to transportation systems.

Construction of transport tunnels

In transportation projects, such as subway lines, high-speed trains or subway highways, tunnel boring machines are essential for the excavation in densely populated areas. The ability to excavate without trenching minimizes surface disturbance, maintaining traffic and urban life while the tunnel is being constructed.

Sanitation and water networks

In water and wastewater infrastructure projects, tunnel boring machines are used to install subway pipelines and networks without disrupting surface activities. Companies such as Eurohinca specialize in trenchless tunneling, using tunnel boring machines for projects requiring precision and low impact.

Subway mining

Hard rock tunnel boring machines are commonly used in mining to create subway accesses and galleries quickly and safely, facilitating access to deposits without performing large excavations on the surface.

Advantages of using tunnel boring machines

The use of tunnel boring machines offers multiple benefits, especially in projects where it is important to minimize surface impact and ensure structural safety.

• Surface Impact ReductionThey allow the construction of tunnels without the need for large open trenches, which reduces damage in urban environments.
• Safety on Unstable GroundsEPBs and slurry TBMs are ideal for working in unstable terrain and in the presence of water, as they stabilize the excavation area.
• Accuracy and EfficiencyAutomated tunnel boring machines can excavate and place casing continuously, which speeds up the construction process and ensures accurate progress.