Tunnel boring machine (TBM) designer and manufacturer Terratec has lowered its earth pressure balance TBM (EPBM) into place for the Metropolitan Waterworks Authority (MWA)’s Ninth Bangkok water supply improvement project in Thailand.
The 4.8m-diameter EPBM was deployed in early October.
The Bangkok water supply improvement project will use three Terratec TBMs to construct a 9.1km water tunnel on Bangkok’s western side to improve water supply capacity and quality.
A joint venture (JV) between Italian-Thai Development (ITD) and Nawarat Patanakarn (NWR) is the project’s contractor. ITD will operate two TBMs, namely S105 and S106, while NWR will manage the S102 TBM.
The S102 TBM was recently installed in Shaft 9B-1 to commence boring approximately 2.2km in the opposite direction, with a goal to connect with Shaft 9A-5 from another contract.
According to Terratec, the TBMs have been designed to meet the project’s precise alignment requirements, with active-type articulation that enables navigation through minimum curve radii of 90m and 80m.
These machines will be the company’s sixth, seventh, and eighth “tight radius” TBMs deployed in Thailand, said Terratec.
The tunnel alignment runs through challenging geological conditions, including silty clayey sand and hard clay layers. To manage these, the TBMs are equipped with soft ground cutterheads featuring a 70% opening ratio and copy cutters.
Additionally, the machines will advance using conventionally reinforced concrete segments, with an additional steel lining to be installed after excavation.
Bangkok’s tunnelling projects have historically faced risks of water and sand ingress, which increases the potential for tunnel collapse. To mitigate this, the project team is said to have implemented rigorous safety protocols and adapted the TBM designs accordingly.
The ninth Bangkok water supply improvement project seeks to increase capacity, reduce leakage, and improve water quality for the city’s residents.
The factory acceptance tests for the three TBMs of the project were completed in October 2022.
