NATIONAL

China building rail tunnel below Great Wall

Micro blasting techniques will be used to shield the heritage structure from construction impact

China is constructing train tunnel of 12 km in length through one of the portions of its iconic Great Wall to connect Zhangjiakou city, which is due to co-host the 2022 Winter Olympics along with Beijing.

It took the Chinese engineers months to choreograph the best intersection point. In the end, the tunnel, deep below the Badaling section of the Great Wall, passed experts’ appraisal, state-run People’s Daily reported.

The line is designed for high-speed trains travelling up to 350 km per hour, which is expected to shorten the journey time from more than three hours to approximately one hour. The line is estimated to be completed in 2019. The depth of the tunnel will range from four metres to 432 metres.

Precise technology

Luo Duhao, chief engineer of the Beijing–Zhangjiakou high-speed railway line, being built by China Railway Number 5 Engineering Group, said the firm will employ “precision micro-blasting” technology, which has a velocity of 0.2 cm per second. The technology is capable of making the impact weaker than the traditional firepower blasts that have a velocity of 5 cm per second.

Mr. Luo told the Global Times that the new technology will ensure that the Great Wall will not be affected by the blasts, as they will be barely felt.

“The new technology causes little damage to the geological environment,” Dai Longzhen, deputy manager of the Beijing–Zhangjiakou line, told the Global Times . “I myself once stood on the Great Wall and I could not feel the blast at all,” he added. Zhang Xuehua, a blast expert at the construction site, told the People’s Daily that the construction of the tunnel has completed 4,500 blasts since early February this year.

In the middle of the tunnel, workers will build a spacious station right under the Great Wall, with a record-breaking construction space of 36,000 sq.m., Xinhua reported. The station will be 102 metres below the surface of the Badaling Great Wall.

Originating from the Beijing Railway Station North, the Beijing–Zhangjiakou line runs through Haidian, Changping and Yanqing districts of Beijing.

Centre of tourism

The line continues northwest through Huailai and Xunhua counties in Hebei province before terminating in the city of Zhangjiakou, making for a total length of 174 km. Built from the third century BC to the Ming Dynasty (1368–1644), the Great Wall stretches over 21,000 km. Over a four million tourists visit the Great Wall every year as it is the centre of China’s tourism campaign.

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