By Lynda Myer
Following broke through of the Terratec 4.27m-diameter EPBM on the cable tunnel in downtown Bangkok in April, tunneling on the Rama III Tunnel Project in Bangkok has been finished.
Used for the Chidlom cable tunnel, the EPBM, which belongs to contractor Italian-Thai Development PCL, was immediately deployed to the Rama III Tunnel Project.
The new high-voltage cable tunnel is one of a series of tunneling projects being implemented by Bangkok’s Metropolitan Electricity Authority to meet increased power demands in the Thai capital.
Tight alignment constraints and navigating the foundations of the overhead bridges along the alignment, are the encountered challenges in the path of this project. This could only be achieved thanks to the EPBM’s X-type articulation system, which could accommodate the very tight radius curves of 85m.
The EPBM’s soft ground cutterhead featured an open spoke design to ensure good material flow and the addition of knife bits to assist break-in and break-out of the concrete shaft eyes.
The installed two types of segments were: 1,200m-long universal tapered precast concrete segments, installed as the machine progressed, and 600m-long steel segments, used during the course of the sharp radius curves.
In accordance with Terratec’s announcement, tunneling activities were closely monitored throughout the project via a settlement monitoring program that demonstrated minimal impact on the available above-ground structures.
Stiff to very stiff clay with lenses of sand and a groundwater head of about 2 bars, were the geological conditions along the 3.5km Rama III tunnel alignment.
The obstacles in the stretch of this project, which is located close to the Chao Phraya River, is heavy traffic and the physical limitations of the built-up area including high-rise buildings and the foundation of the overhead bridge.
According to Terratec: “The logistics during the EPBM’s launch and operation were extremely challenging, especially during the transportation and delivery of oversize parts for assembly on site.”
