Being designed to alleviate flooding, the digging process of the Samui Island flood control scheme’s 1.1km tunnel in Thailand was completed by Contractor SCG (1995) Co Ltd using a refurbished Terratec S48C EPBM.
According to Terratec: “The EPBM, featuring a classic soft ground open spoke cutterhead design, with knife bits to assist break-in and break-out of the steel fiber-reinforced concrete shaft eyes, coped well with the geological conditions along the alignment. They consisted of dense sand, stiff to hard clay, and decomposed rocks with a groundwater head of about 2 bars.”
While the location of receiving shaft with 5×9 m dimensions was at the bottom of two hills where flooding lies, the process of draining flood water through the new tunnel and linking with a 500m open canal to the sea will be done. Also transferring the process of muck to muck cars and out to the surface can be easily done using Terratec’s non-tuck hose system.
Placed on the east coast of Thailand, Samui Island is the country’s second-largest island after Phuket and its annual capacity for attracting tourists is over 2.7 million. Due to the significant problem of Samui in facing a severe flood, the intended tunnel is planned to ease flood waters. As part of the main Ring Road revitalization and improvement project, the tunnel will improve rainwater collection from roadway run-off along Samui’s main ring road.
The former project of this 3.20m diameter EPBM was Bangkok Metropolitan Electricity Authority’s Phra Khanong Cable Tunnel Project and in order to negotiate the piles of an adjacent expressway ramp, Thai contractor Nawarat Patanakarn PCL bored a sharp 32m-radius curve as it exited the project’s launch shaft.
Providing a maximum articulation angle of 6.6 degrees, to achieve the challenging curved alignment, the EPBM featured an extreme X-type articulation system. As the first of a series of tunneling projects to meet increased electricity demand in the Thai capital, the Phra Khanong Cable Tunnel Project was designed to accommodate a new high-voltage cable system.