The 3rd Annual Urban Underground Space and Tunneling was held in Singapore on March 27. At the conference which is aimed at offering participants insights on state-of-the-art techniques, Mr. Henry Foo Yung Thye, Project Director, Thomson East Coast-Line Civil Team 3, was invited to share the experience on the use of the RTBM (Rectangular TBM supplied by CREG whose nickname is THEMIS) to construct a 150m long trenchless pedestrian underpass, as part of the construction for Thomson East Coast Line Contract T221 Havelock Station.
Participants are invited to visit the RTBM model
THEMIS, the rectangular TBM (7.620m×5.645m) was adopted for the very first time in Singapore and completed its drive in November, 2016. It was awarded the Project of the Year Award (SPMI PoY) 2016-2017 in Engineering & Construction Category. This new method of construction has shown that it could improve manpower productivity by an approximate 30 percent.
The impressive performance of THEMIS has everything to do with the close cooperation between the project client Singapore Land Transport Authority (LTA), the main contractor Gammon Construction Limited Singapore Branch and the Specialist Sub-Contractor China Railway Tunnel Group (CRTG).
Rectangular Tunnel Boring Machine cutS a square face rather than a circular one by conventional TBMs. Moreover, as a trenchless way to excavate short-distance tunnels at shallow depths, its space utilization has increased by 20% in comparison to that of circular TBMs. That distinct advantage makes it an ideal choice for unban underpass and the subway exit and entry construction.
In 2013, CREG developed and manufactured two Rectangular TBMs (10.12×7.27m and 7.52×5.42m) to excavate motorways and sidewalks respectively for Zhengzhou Zhongzhou Avenue Undercrossing Tunnel Project. The two machines completed the four tunnels on September 2014. Unlike conventional cut and cover construction method where surface interventions are often required, the use of a RTBM resulted in a simpler and safer construction, and significantly reduced the volume of construction activities being carried out from the ground surface, hence resulting to a much conducive construction environment within the very densely populated area, with minimal noise and dust generated. The pioneer and successful use of the RTBM sparked interest from media, governmental agencies, and professionals both at home and abroad. That’s how CREG secured a RTBM order from the LTA.
CREG spares no effort in to find new possibilities of the RTBM. On 19 August, CREG’s rectangular TBM Jiangong broke through in Chengdu, Sichuan. It is the world’s first of its kind applied to cobble sand ground up to this day. The underpass project takes place at a critical zone. Only 3.1m above the underpass is Chengdu Metro line 1. In-between the tunnel and ground lie 15 municipal pipelines among which the nearest one is simply 0.5m away from the underpass. The construction must ensure continuous ground traffic, no damage to municipal pipelines and minimum disturbance to the metro line 1 overhead. All those challenges make the tunneling project one of the most complicated urban construction works in Sichuan Province and even the country.
Overwhelming growth of cities in developing countries is creating a strong demand for new underground infrastructure. The underground space is an important potential resource, where effective utilisation of urban underground space can perfect the urban comprehensive function. The RTBM developed by CREG proves to be a powerful tool suitable for urban underpass, underground expressway and its ramp, underground utility tunnel and parking lot. CREG is now working on the trenchless technology of station building. The company shall continue its innovation convention and explore the tunneling aspects to address the problems of urban sprawl, traffic congestion and pollution.