What Technology Did Thailand Use to Build Its Underwater Train Tunnel?

• 7 March 2018
• Construction Focus
• 8239 Views

Thailand recently revealed the completion of construction on the Samnam Chai underground train tunnel, which is the first ever train tunnel in Thailand to go beneath the Chaopaya River.

SCG, in cooperation with Ch Karnchang Plc, took Construction & Property Magazine on an exclusive tour into the tunnel to find out what technology are being applied in order to successfully build the tunnel.

Located 32 metres below ground level, Chanam Chai station is part of the 27-kilometre long MRT Blue Line extension connecting Bang Sue to Tha Phra and from Hua Lamphong to Bang Khae under the operation of the Mass Rapid Transit Authority of Thailand (MRTA).

Ch Karnchang was one of the five contractors assigned by the MRTA to build the Sanam Chai station and responsible for the 2.6 kilometre rail tunnel under the Chao Phraya River, where SCG was the concrete supplier to the project.

To achieve such a huge engineering challenge, modern manufacturing technology and strong, durable structures were required. In fact, engineering design plays a very important role, but the key and the most significant factor is the concrete.

Humidity and chemical elements in the soil such as seepage and the amount of sulfate and chloride were taken into consideration, as these directly affect the strength and durability of the structure.

Aggregate mixed into the concrete must also meet certain specifications beyond the normal required criteria such as size, cleanliness and strength.

SCG also took into consideration other specifications to ensure the lifespan of the structure, such as using the Alkali-Aggregate Reaction criterion to increase the durability of the concrete, prevent deterioration, and suitability for the usage.

There were various types of concrete used on the project:

1. Fast Setting Concrete – Special strength concrete sets faster than normal, is suitable for usage in projects with a limited construction timeframe such as roads and express ways.

2. Bored Pile Concrete – Improved formula concrete with bore piles. Reduced bleeding and higher durability and perfect for building underground.

3. High Early Strength Concrete – Extra-strong concrete that sets faster than normal and has less shrinkage. With reduced Alkali Silica reaction, the concrete is perfect for large infrastructure projects, allowing construction to be carried out faster.

4. Waterproof Concrete – Tightly packed concrete with high impervious and lower coefficient of permeability than normal concrete.

After starting construction on the project in 2011, Sanam Chai MRT station construction has been completed and is currently undergoing system installation. Sanam Chai Station as well as the whole project is expected to open for the public next year.