EPB earth pressure tunnel boring machine

Q: What is an EPB TBM and how does it work?

An EPB (Earth Pressure Balance) tunnel boring machine is a closed shield that maintains pressure balance at the excavation face by using the excavated soil (usually conditioned) inside the shield chamber. Coordinated control of pressure, advance, and material removal helps stabilize the face and reduce the risk of ground loss and settlement.

Q: What are the main benefits of using an EPB TBM?

It provides control over the pressure at the face, improves stability in soft or mixed soils, reduces the risk of ground loss and surface settlement, and makes it easier to meet tolerances in sensitive environments by monitoring and adjusting excavation parameters.

Q: How is the pressure in the tunnel face controlled with an EPB TBM?

Pressure is controlled by managing the volume of material in the chamber and regulating the auger extraction, while coordinating the feed rate and the thrust of the cylinders. Soil conditioning can adjust workability and help maintain a stable balance.

Q: What kind of soils are most suitable for using an EPB TBM?

It is often particularly suitable for soft or mixed soils containing fine particles and having low to medium permeability, where the prepared ground allows the face to be stabilized. In highly permeable granular soils with high water pressure, a slurry wall is often considered, depending on the specific circumstances.

Q: What technology is used in EPB TBMs to ensure accurate excavation?

Geometric guidance and control systems (such as laser references and sensors) are used in conjunction with operational control of thrusts and corrections to maintain alignment and elevation within tolerances.

Q: What measures are taken to protect nearby infrastructure during excavation of an earth pressure shield tunnel?

They are protected by maintaining pressure balance at the face, controlling excavation and advance to prevent loss of ground, and monitoring parameters and surveying the surrounding environment using action thresholds to minimize the risk of subsidence and adverse effects.

Eurohinca (Europea de Hincas Teledirigidas, S.A.), Trenchless specialist since 1996 - 14 TBMs and >120 km executed.

The closed shield (EPB) allows for excavation in saturated, fine-grained soils with control over face pressure, alignment, and watertightness — ideal for crossings and service tunnels. View pipe jacking (microtunneling), segment tunnel, choice of tunnel boring machine, technical assistance and engineering y references.

Excavation with EPB earth pressure tunnel boring machines (TBMs)

At Eurohinca, our EPB earth-pressure balancer tunnel boring machines are designed to effectively address the challenges of excavation in soft or low-cohesion soils. This type of closed shield It works by stabilizing the excavation face using balanced pressure, making it an ideal solution for urban tunnels.
This technique is complemented by other advanced methods, such as the Direct Pipe, which combines features of directional drilling and microtunneling, or the horizontal directional drilling, ideal for trenchless projects in sensitive areas.

Advantages of using a tunnel with an earth pressure shield

Choose a EPB (Earth Pressure Balance) tunnel boring machine It offers significant advantages: control of forward pressure, safe advancement in complex soils, and minimal surface disturbance.
This type of machinery has played a decisive role in numerous projects involving urban sewage systems, drainage works y gas pipeline tunnels.
For more extreme conditions, such as saturated soil or soil with a high water table, you may opt for a hydro shield, another type of closed-shield method using slurry injection for stabilization.

This technology is supported by the ITA-AITES Guidelines on Mechanized Excavation, an international benchmark for the planning and operation of containment structures.

EPB Closed-Shield Service Specifications

The EPB (Earth Pressure Balance) closed shield is a tunnel boring machine designed to maintain pressure balance at the excavation face using the excavated material itself, which has been pre-conditioned. The application of this technology in microtunneling and mechanized tunneling is defined by the following technical parameters:

• Main applications: Sensitive urban intersections, tunnels in areas with nearby buildings, underpasses beneath roads or railways, work on soft or unstable ground, sites at risk of settlement, and projects involving the water table.

• Compatible land conditions: Cohesive soils, silts, clays, fine sands, or materials that exhibit plastic behavior after conditioning. In granular or highly permeable soils, conditioning the detritus and controlling pressure are essential to prevent losses.

• Pressure control mechanism: The EPB cutterhead operates under pressure using the excavated material itself, which is treated with foam, polymers, or additives. This helps stabilize the cutting face, control the advance, and prevent voids that could cause surface movements.

• Construction method: Excavation using a cutting head, mixing and conditioning in a pressurized chamber, removal of material via an auger, and installation of the lining (driven pipes or segments) depending on the type of project.

• Range of diameters and lengths: Suitable for microtunnels and tunnels of medium and large diameters. The permissible lengths depend on the thrusting power, soil resistance, site logistics, and lining design.

• Civil works prerequisites: Launch and reception shafts or portals with space for the tunnel boring machine, foam and additive injection systems, a lining assembly area, ventilation, and auxiliary equipment. In urban areas, the project requires coordination with existing utilities.

• Guidance and Control System: Continuous monitoring of chamber pressure, torque, thrust, feed rate, and excavated volume. Guidance is provided by laser or gyroscope, depending on the alignment tolerances.

• Excavation and Management of Excavated Material: The processed tailings are discharged via the screw conveyor onto conveyor belts, dump cars, or pumping systems, depending on the diameter and the project's logistics plan.

• Quality control and safety: Monitoring of pressure balance, inspection of the worm screw’s condition, shield tightness, adequate ventilation, safe access protocols, and geometric verification of the casing after each advance.

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International Experience

Projects around the world

Thanks to our experience with techniques such as pipe ramming and closed-shield tunneling, we have carried out projects in more than 20 countries.
From submarine emissaries to river and watercourse crossings, Eurohinca has participated in landmark projects that require precision, sustainability, and cutting-edge technology.
Learn more in our works executed.

EPB Tunnel Boring Machine: Rapid Response

What is the EPB method with segments?

A EPB diagram with segments refers, in general terms, to the construction of a tunnel using EPB-type closed shield and coating using voussoirs (segments) that make up the tunnel ring. To place it within the selection of equipment, this may help you choice of tunnel boring machine.

When to use

It is used when the project requires a closed shield and a lining with voussoirs depending on the terrain, the route, and environmental constraints. To compare families of closed shields, you can see hydro shield or the main page of closed shield tunnel boring machines.

Key data

Preliminary alignment and objectives for the section (tunnel section/use and environmental constraints).
Soil information available (geotechnical or references) and presence of water if known.
Implementation and construction constraints (access points, land use, unique features).

Recommended information

Longitudinal profile and sensitive sections of the route (if any).
Requirements for the owner/operator (if applicable) and acceptance/operational criteria.
For some background on segmental solutions, it may be helpful to segment tunnel and, to understand the EPB method, EPB closed shield.

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News that may interest you

Consult our Latest news on EPB tunnel boring machines and other excavation methods, where we explore real-world applications, technical advances, and comparisons with other systems such as conventional pile driving or open-shield microtunneling.

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Frequently asked questions on closed shield TBMs

Get answers to your questions about how the earth pressure tunnel boring machines, its application in different soils, and how it differs from other technologies such as the open shield or the conventional planting. Check them all out on our frequently asked questions section.

What is an EPB TBM and how does it work?

A EPB tunnel boring machine (Pressurized Earth Balance) is a type of earth pressure shield that excavates tunnels while maintaining a constant pressure at the tunnel face. It works by using the excavation spoil to balance the pressure and avoid subsidence. This type of TBM is ideal for soft or mixed soils, providing stability and safety during the excavation process.

What are the main benefits of using an EPB TBM?

The EPB tunnel boring machines offer several key benefits, such as precise control over ground pressure, which reduces the risk of collapse. In addition, they enable excavation in difficult terrain and tunnel construction with less impact on surface infrastructure. They also help maintain tunnel stability and facilitate efficient muck removal.

How is the pressure in the tunnel face controlled with an EPB TBM?

In a EPB tunnel boring machineThe pressure in the tunnel face is controlled by the use of rubble accumulated in the extraction chamber. This material helps to balance the pressure exerted by the ground. The spoil is extracted by means of a worm screw, and the speed and force of the thrust cylinders adjust the pressure to maintain tunnel stability.

What kind of soils are most suitable for using an EPB TBM?

The EPB tunnel boring machines are especially effective in soft, mixed or high water soils. This equipment is designed to handle challenging terrains in terms of stability and pressure, allowing tunnels to be constructed safely and efficiently in difficult conditions.

What technology is used in EPB TBMs to ensure accurate excavation?

The EPB tunnel boring machines use advanced technologies such as laser systems and levels to guide the shield and ensure precise excavation. These systems allow precise control of tunnel direction and alignment, optimizing the excavation process and minimizing the impact on surface infrastructure.

What measures are taken to protect nearby infrastructure during excavation of an earth pressure shield tunnel?

To protect nearby infrastructures during the excavation of a tunnel using earth pressure shield o EPB tunnel boring machineIn addition, the tunnel face pressure is meticulously controlled and the ground is continuously monitored. The accumulation and transport of muck, along with precise adjustments in auger speed and thrust cylinder force, help prevent subsidence and damage to surface structures.

Solve your doubts in our section of frequent questions.