Completion of the 3.3km MRT Orange Line (East section) project at Hua Mak Station has been celebrated following the final breakthrough of a TERRATEC 6.39m diameter EPBM driven by contractor Italian-Thai Development PCL (ITD) on one of three underground civil works contracts for the first 23km-long (East Section) phase of the Mass Rapid Transit Authority of Thailand’s (MRTA) Orange Line Project.
The Eastbound tunnel breakthrough on Contract E3 was achieved way ahead of schedule. Contract E3, which was awarded to ITD in May 2017, totals over 6km of TBM driven tunnel and three underground stations, extending from Khlong Ban Ma to Hua Mak. After completing the Westbound tunnel on Jan. 20, 2020 with the best month ever in Thailand with progress of 663.4m, th EPBM began mining eastwards from the Khlong Ban Ma station box on April 26, 2020, and quickly got up to speed following its initial drive. By mid-June 2020, the TBM was achieving the best rates of 33 rings per day (46.2m/day – another best every advance rate per day) and had already undertaken its first intermediate breakthrough.
In March 2020, The Westbound tunnel breakthrough on Contract E3 took place a full month ahead of schedule. The Eastbound tunnel breakthrough on Contract E3 has been achieved 118 days ahead of schedule.
The TERRATEC S70 TBM was designed to tackle the variable soft ground geology of the city – which ranges from soft and medium to stiff and very stiff clays, with lenses of dense sand and the potential for high-pressure groundwater inflows – as well as the need to mine through numerous diaphragm wall shafts and potentially, concrete piles.
In order to handle these challenging conditions, the TBM’s soft ground cutterhead features a spoke style and the addition of back-loading knife bits to assist the break-in and break-out of the shafts. In addition, the machine is fitted with an active bentonite face support injection system and double-gated screw, to ensure face stability and mitigate settlement during excavation in areas of flowing sands and high groundwater pressure.
As the machine progresses along the alignment, it has been installing a precast concrete segmental lining consisting of five x 1400mm wide Universal style segments plus key, with an internal diameter of 5.7m.
In total, TBM tunnelling operations for ITD’s Orange Line (East) contract has lasted two years.
Bangkok’s new Orange Line will eventually total about 35.9km with 26.2km aligned underground with 22 underground stations and another 9km and seven stations on elevated structures. The line is scheduled to open in March 2024. When completes, the Orange Line will provide a vital transportation link from Bangkok’s city centre to districts in the east, reducing traffic congestion and paving the way for improved accessibility, economic growth and new residential and commercial opportunities along the alignment.
A video of the TERRATEC S70 TBM breaking through on Bangkok Orange Line can be found here: https://www.youtube.com/embed/vyUxVuO1RwY