DRILL RIGS AND GROUND SUPPORT | ROCK TUNNELS


PROJECTS Among the recent tunnel projects where Sandvik’s equipment systems have been used are the Shinnozoki Tunnel, in Japan, and the Bonzolo Bypass, in Italy. For the former project the contractor use an automated jumbo for blasting, and sees potential for unmanned operations in tunnelling in future; and, in the latter project the primary ground support element was a noted focus, calling for pipe umbrella and hollow bar anchors (see box panel).


Shinnozoki Tunnel, Japan Japanese contractor Taisei Corporation is an early adopter of advanced mechanisation, remote control and digital technologies in construction. It started using Sandvik’s fully automated jumbo in 2020. The DT1131i three-boom automated jumbo was employed on the Shinnozoki Tunnel project, which is 1150m-long and located in mountains on the border of Yamagata and Akita prefectures. The tunnel has a cross-section of more than 100m2


. The jumbo is built on Sandvik’s advanced i-series


platform and especially engineered for demanding tunnelling and cavern excavations, says the manufacturer. It combines high drilling accuracy, reach, and intelligent control systems to optimise drilling patterns, reduce overbreak and improve tunnel quality, it adds. Early in the Shinnozoki project, Taisei’s team recognised


the need to modernise their approach. “In order to keep up with the times, we have been proactive in introducing these cutting-edge machines from overseas,” says Shingo Miyamoto, Construction Engineering Dept Manager, Tunnel Section, Taisei Corp. But deploying a fully automated jumbo as the sole machine for both blasting and rock-bolting – as is common in Japan – quickly revealed limitations. They were unable to maximise the benefits of the fully automatic jumbo with this method of tunnelling, so instead the machine was used to focus exclusively for drilling blast holes, explains Wataru Tanno, On Site Representative, Taisei Corp – Shinnozoki Tunnel. According to Miyamoto, the shift required dedicated support. “After all, it was a completely different machine from the one we’ve used up until now,” he explains. “It was important to provide adequate instruction on how to use the machine. First, Sandvik’s experienced engineers came from their home country, and we received solid support day and night.” Japan’s unique tunnelling environment, characterised by


challenging rock conditions and requiring closely spaced steel arches, demanded specialised capability. Pekka Laine, Product Engineer at Sandvik says: “In Japanese excavation, it’s a challenging business because of the rock conditions... normally they use only one-metre rounds and the steel arches are put in every one metre. With the Sandvik DT1131i, there is one feature which is not used anywhere else in the world. It is made especially for these steel arches.” Automation unlocked new performance potential for the


project. Hiroaki Kobayashi, Chief Civil Engineer, Yoshioka Corp, says: “Using a fully automatic jumbo, I think the biggest advantage is that it’s possible for an operator to perform drilling work alone.” He adds that when the project began they were told that drilling contour holes with a fully automatic jumbo


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was not possible. But with Sandvik having a unique way to drill such holes its became possible to do so with the fully automatic jumbo. Accuracy and efficiency gains followed. Adopting a spike-type centraliser allowed stable drilling to be achieved. The consumption frequency of parts such as rods, bits and shank rods was reduced, and lost time minimized compared to conventional drilling. Operators say the DT1131i’s top-mounted booms


give good visibility and the automatic drilling system reduces damage on the hydraulic hoses. Automation has been delivering consistency and


resilience. “Using the fully automatic jumbo, the drilling results were the same, no matter which operator. The same results can be consistently achieved, even if someone is absent due to illness,” said Miyamoto. “I believe that this has greatly contributed to the


stability of the drilling process. We would like to raise the level of utilisation of these labour saving machines throughout Japan.” Taisei sees even greater potential, such as for unmanned operations in the future.


Edited version of report, based on case study by Carly Leonida. Photos by Unou Jikeen Agency.


Below: DT1131i combines high drilling accuracy, reach, and intelligent control systems optimise drilling patterns, reduce overbreak and improve overall tunnel quality.


Above:


DT1131i in Shinnozoki Tunnel project.


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