Smart drilling, consistent results

The company was an early adopter of advanced mechanization and digital technologies. Shingo Miyamoto, Construction Engineering Dept Manager, Tunnel Section, Taisei Corp, explained: “We started using Sandvik’s fully automated jumbo in 2020, further to the stronger and stronger trend for automation, mechanization and remote control of machines in the tunnelling construction industry.”

The Shinnozoki Tunnel project, which spans 1.148 kilometres on the border of Yamagata and Akita prefectures, was an ideal setting to put the fully automated, three-boom jumbo, Sandvik DT1131i to the test. Takafumi Toyama, Managing Engineer, Taisei Corp, Shinnozoki Tunnel, said: “[Shinnozoki Tunnel project] is a large mountain tunnel with a cross section exceeding 100 square meters.”

Built on Sandvik’s advanced i-series platform, Sandvik DT1131i is specially engineered for demanding tunnelling and cavern excavations like those at Shinnozoki. It combines high drilling accuracy, excellent reach, and intelligent control systems that optimize drilling patterns, reduce overbreak and improve overall tunnel quality.

Early in the project, Taisei’s team recognized the need to modernize their approach. “In order to keep up with the times, we have been proactive in introducing these cutting-edge machines from overseas,” Miyamoto said.

But deploying a fully automated jumbo as the sole machine for both blasting and rock-bolting – as is common in Japan – quickly revealed limitations. “We learned that we were unable to maximize the benefits of the fully automatic jumbo [with this method]. So, we have introduced this Sandvik fully automatic jumbo as an excavation machine exclusively for drilling blast holes,” said 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 explained. “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, characterized by challenging rock conditions and requiring closely spaced steel arches, demanded specialized capability. As Pekka Laine, Product Engineer at Sandvik explained: “In Japanese excavation, it’s a challenging business because of the rock conditions… normally they use only one-meter rounds and the steel arches are put in every one meter. 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, explained: “Using a fully automatic jumbo, I think the biggest advantage is that it’s possible for an operator to perform drilling work alone.”

He continued: “When this project first began, we were told that drilling the contour holes with a fully automatic jumbo was not possible. But being different from other companies, Sandvik has a unique way to drill the contour holes, and this difference has made it possible to drill the contour holes with the fully automatic jumbo.”

Accuracy and efficiency gains followed. By adopting a spike-type centralizer, stable drilling can be achieved. The consumption frequency of parts such as rods, bits and shank rods has been greatly reduced and lost time has been minimized compared to conventional drilling.

Operators also praised the machine’s design, noting that the DT1131i’s top-mounted booms allow excellent visibility and the automatic drilling system reduced the damage on the hydraulic hoses.

Looking ahead, Taisei sees even greater potential. “I think we could see unmanned operations in the future,” said Toyama. “I hope to advance the tunnel industry one step further with Sandvik.”

Above all, automation is 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 utilization of these labor saving machines throughout Japan.”