TRIAL by WATER

At the No 4 inclined wellhead of the Qinling Mountains Water Conveyance Tunnel in Northwest China's Shaanxi province, hot steam continuously jets out.

At the excavation site about 10 kilometers away from the wellhead and 1,840 meters deep, more than 100 workers, shirtless, are busy digging, cleaning and transporting in a tunnel with a temperature of more than 40 C, relative humidity of 90 percent and virtually no natural wind. It's like a big sauna house in the dark. Sweat constantly seeps from the workers' body, condenses on their skin and hair ends, and finally merges into water lines, dripping into the mud.

This is the first time that a tunnel has been dug into the base of the Qinling Mountains, one of the top 10 mountain ranges in the world. As the top priority of the Hanjiang-to-Weihe River water diversion project, also known as the south-to-north water transfers project of Shaanxi province, the task is to introduce Hanjiang River water into Guanzhong area to ease water supply strains in large-and medium-sized cities such as Xi'an, Xianyang, Yangling and Weinan in central Shaanxi.

Upon completion, it will greatly alleviate the water shortage in urban construction and industrial development along the Weihe River. The project covers an area of 14,500 square kilometers and a beneficiary population of 14.11 million.

It has inspired grandiose ambition, and the workers have made a silent vow to the project. For more than 2,000 days and nights, in the Qinling Mountains Water Conveyance Tunnel, they work on a 12-hour shift. With the rapid pace of technological innovation, the tunnel-boring machines are more reliable with radar sensors stopping them from crashing. They roll 24 hours a day. The tunnel borer can only advance 3 to 4 meters a day, but every meter is made at the price of sweat and toil. In the tunnel with high temperature and humidity, it is just normal for the workers to put up with dizziness, vomiting and even fainting. What scares them most is the geological disasters and nobody knows when they will happen.

The Hanjiang-to-Weihe River water diversion project is full of challenges. Geological disasters such as fault landslides, rock bursts, hard rocks, water inrush, and harmful gases often occur during the construction of the water tunnels in Qinling Mountains.

The comprehensive difficulty is unprecedented in the world and constantly refreshes national record. When the underground river is dug to cause serious water inrush, the amount of water flowing out of the tunnel in a day is enough for the population of a medium-sized county. The rock at the southern foot of the Qinling Mountains is harder than the steel plate, and the tunnel borer usually encounters a rock burst every two meters on average.

In the course of the project, workers once encountered strong water inrush of 46,000 cubic meters a day. As the temperature inside the cave exceeds 40 C, the rock would become very hard and the tunnel borer seems to drill on a steel plate. Emergency holes are built to prevent the tunnel construction from flood. Quality inspection was controlled in the highest standard.

The poor working environment has made some workers quit every month, but most workers still stick to the "hot" position. On a cold winter day, taking a cold shower in a crude shower room in the tunnel has become their most pleasant moment of the day.

Accompanied by the thunderous rumbling and vibration of the tunnel borers, the tunnel advances day by day, but what remains unchanged is that when the workers safely end their day's work by taking 20-minute tunnel car and a 30-minute bus ride, the whole crew cheers.