A new type of tunnel-boring machine designed to excavate through fissured limestone recently made its global debut with a breakthrough on Kuala Lumpur's emerging mass rapid-transit system. Six new variable-density-slurry tunnel-boring machines (VDTBM) are deployed on the 9.5-kilometer-long twin drives of the Malaysian capital's notoriously difficult karstic ground.
With the first VDTBM drives completed this January, the technology "is an unqualified success," reports Gus Klados, project manager with the joint venture of locally based MMC Corp. Bhd. and Gamuda Bhd. "We stopped several major slurry leaks to karst fissures and to nearby excavation pits of other developers," Klados adds.