Seoul blasts through a granite mountain pass Nov 2011
Sandvik News Release
Excavation has started on a 5km highway tunnel through a granite mountain overlooking Seoul in South Korea.
  • Seoul, from the Gwanaksan granite mountain top

    Seoul, from the Gwanaksan granite mountain top

  • Sandvik DTi jumbo prepares a topheading round

    Sandvik DTi jumbo prepares a topheading round

Specialist rock tunnelling contractor Taeah is using drill+blast to excavate almost half the length of the twin tube tunnel on the 12.4km stretch of six-lane highway between the Geumcheon technology business district and the upmarket residential district of Seocho on the southern side of the South Korean capital.
The highway, known as the Kangnam Beltway, needs to pass through the Gwanaksan mountain, a 632m-high granite formation whose name in Korean means "hat-shaped peak". The mountain itself is a tourist magnet, and its slopes are home to the Buddhist hermitage of Yeonjuam and the dramatic Yeonjudae, a Buddhist hall perched on a granite cliff.

Project Manager Seong-su Kim

Taeah Project Manager Seong-su Kim reported that since tunnelling started from in front of the main campus of Seoul University in July, excavation on the company's 2.4km contracted share of the tunnel had progressed by 338m by October.
After encountering all five grades of rock initially ranging from Type I hard granite through to Type V granite/soil mix, Kim said that only Types I and II were blasted during 175m of excavation in September.
Taeah is using a Sandvik DTi jumbo with three booms that can cover a face ranging from 20-203m2. The rig is fitted with Sandvik's new tunnel planning software, iSure. The system offers a way of simultaneously working with optimised drilling and blasting patterns to reduce the need for scaling, increase rock loadability for mucking, and ensure smoother collaring in the following round.
The main tunnel is 20m wide x 10m high, with a shorter stretch of 14m x 9m, and is being advanced on a topheading and bench cycle. Charge hole diameter is the standard Korean specification of 45mm. During summer six blasts a day are being carried out, although this is expected to reduce to four or five in the winter.
The Sandvik jumbo is operating 24 hours a day, to drill face charge holes in each of the twin tubes alternately. The complete highway contract is being carried out for Kangnam Beltway and is scheduled for completion in May 2013.
  • Scope of the project

    Scope of the project

  • Seoul University portal

    Seoul University portal

  • Jumbo at fully extended reach

    Jumbo at fully extended reach

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