The Process of Tunnel Lining: From Aggregate Production to Concrete Placement

✅Aggregate for the concrete lining is produced from local sources, such as dolerite, and crushed on site.

🔧Concrete additives are used to enhance workability and adjust the moisture content of the aggregates.

🏗️Concrete is placed using pneumatic placers or slip form pavers, ensuring efficient and uniform placement.

🚧Grouting is performed to fill any cavities between the concrete lining and the surrounding rock.

🔨Defective areas in the tunnel lining are repaired by removing the damaged concrete and applying epoxy resin or shotcrete.

What are the main materials used in tunnel lining?

—The main materials used in tunnel lining are aggregates (such as dolerite) for the concrete and cement for binding the aggregates together.

Why is the moisture content of aggregates important in concrete production?

—The moisture content of aggregates affects the consistency and workability of the concrete. It needs to be carefully controlled to achieve the desired quality.

What are the advantages of using pneumatic placers for concrete placement?

—Pneumatic placers allow for efficient and uniform concrete placement, reducing manual labor and ensuring consistency in the tunnel lining.

What is grouting and why is it necessary?

—Grouting is the process of filling any voids or cavities between the concrete lining and the surrounding rock. It helps enhance the integrity and stability of the tunnel lining.

How are defective areas in the tunnel lining repaired?

—Defective areas in the tunnel lining are repaired by removing the damaged concrete and applying epoxy resin or shotcrete, depending on the extent of the damage.

00:14The video introduces the concept of tunnel lining and the importance of the orange fish tunnel in the Cape Province as an example.

00:38Aggregate production for the concrete lining involves crushing dolerite on-site using gyratory crushers and rod mills.

01:07Concrete batching plants are used to produce concrete by weighing and mixing the aggregates either wet or dry.

06:57Concrete is transported to the tunnel using truck mixers and then dropped down the shaft to the kettle for remixing.

10:05The concrete is blown into the shutter using pneumatic placers and consolidated with internal poker vibrators.

12:12Grouting is performed to fill any cavities between the concrete lining and the surrounding rock, ensuring stability.

13:24Defective areas in the tunnel lining are repaired by removing damaged concrete and applying epoxy resin or shotcrete.

14:23The final step involves grinding rough and high spots on the tunnel lining for a smooth finish.