Tunnel drive

Construction of a new motorway tunnel in Korea has been fast tracked using technology originally developed for the mining sector. Contractor Sung Bo Developments is building the western half of a 2.3 km tunnel on the Pyeoungtak-West Ansung Highway 40 project, while the eastern half is being constructed by Nansun Construction Company. The twin dual lane tunnels will both be 14 m wide and 8.5 m high.

Both contractors are using Tamrock rigs to drill blast holes for the construction - Nansun has a Titan 316 - 150 rig and Sung Bo is using an Axera 3 boom. “We recognised that excavating the rock could be a problem right from the start of the project,” said Sung Bo project manager Mr Lee. “The rock is a black biotite gneiss and is very fractured and highly variable.”

To overcome the potential problems, Sung Bo opted to Use Sandvik's Alpha 330 tools to drill the blast holes. The Alpha tools were originally developed for the mining sector and the 330 system has a specially developed larger thread than the original R32 system, which strengthens the tool and improves durability.

Sung Bo is pleased with the improvements and found the lifespan of the new tools was +30% greater than the previous R32 system. According to Sung Bo's rig operator, the Alpha 330 eliminated 'gooseneck' breakages and has achieved around 4000 m of boring per rod.