MMC-Gamuda's tunnel boring machine up for award

KUALA LUMPUR: The Variable Density Tunnel Boring Machine (VD TBM), used in the underground works of the Klang Valley Mass Rapid Transit (Sungai Buloh-Kajang Line), has been shortlisted for this year’s Technical Innovation of the Year award held under the auspices of the London-based New Civil Engineer and the Switzerland-based International Tunnelling and Underground Space Association.

The annual International Tunnelling & Underground Space Awards recognises excellence in the delivery of international tunnelling and underground space projects.

Jointly designed and developed by MMC-Gamuda and Herrenknecht AG engineers, the VD TBM was shortlisted for significantly improving safety in tunnelling operations through the highly variable and challenging karstic limestone ground conditions in Kuala Lumpur, while significantly reducing incidences of sinkholes.

“With the technological innovation of the VD TBM, we have successfully completed the tunnelling works for the extremely challenging karstic limestone section of the SBK Line since July this year, measuring a total tunnelled length of 7.5km – with only two minor sinkhole incidents.

“Comparatively, this is a 95% reduction from the more than 41 sinkholes that occurred when we tunnelled a distance of 9km under the same karstic limestone terrain for the Stormwater Management and Road Tunnel (Smart) project back in 2003,” said MMC Gamuda KVMRT (T) Sdn Bhd Construction general manager Ubull Din Om.

“On a per km basis, this equates to 4.5 sinkholes per km for Smart versus only 0.3 sinkholes per km for SBK Line.

“It is a major improvement by any standard,” said Ubull, adding that there has been almost zero impact on existing properties located along the tunnel alignment during the tunnelling process.

Seen as a breakthrough in tunnelling technology, the VD TBM used in the SBK Line produces “varying density” slurry when tunnelling in unpredictable ground conditions – an innovation that is known to be the first of its kind in the world.

Leveraging from the Smart Tunnel experience, VD TBM is a new class of tunnelling machine that can safely bore through inter-connected underground cavities in karstic limestone formation with minimal or zero risk of causing ground subsidence.

With this tunnelling advancement, karstic limestone will no longer be a barrier to building underground spaces in a highly urbanised environment like Kuala Lumpur.

For the tunnelling industry worldwide, VD TBM has opened up new possibilities for new tunnelling projects around the world, where tunnelling was previously thought not possible due to challenging geological conditions.

Herrenknecht AG founder and chairman Dr Martin Herrenknecht expressed confidence in VD TBM bagging the innovation award.

“It (the VD TBM) is a ‘real technological innovation’ since the Earth Pressure Balance TBM was introduced 30 years ago. The world has to wake up to this (technological breakthrough),” said Herrenknecht.

Separately, MMC-Gamuda presented a paper on the VD TBM’s technological breakthrough and the successful completion of karstic limestone tunnelling in Kuala Lumpur at The British Tunnelling Society Conference and Exhibition 2014 in London on Sept 23.

The winners of the International Tunnelling & Underground Space Awards 2014 will be announced on Dec 4 in London.