In the belly of the dragon
Tunnel workers overcome harsh conditions for river transfer project
Since the Ming Dynasty (1368-1644), the city of Yixing has been an important center for ceramic production in China. Kilns could once be found in Qinglong (Green Dragon) Mountain, Huanglong (Yellow Dragon) Mountain, Shushan, Qianluo and other places. Over the centuries many of the ancient kilns have been lost, but in Qianshu, a village in Dingshu town of Yixing, Jiangsu province, a traditional dragon kiln has survived. Several times a year smoke can even be seen rising from the mountain ridge, emanating from that 600-year-old kiln. It stands alone, the sole kiln in Yixing that produces ceramics using the traditional method.
“The last time we lit up the fire in here, China Central Television came up to make a video of us,” says Zhao Chunqiang, a young caretaker of the Qianshu Dragon Kiln.
“The reason we light it up only a few times a year is that it costs so much. The dragon kiln costs as much as 1 million yuan for each use.”
Dragon Kiln, or Long Yao, is a unique type of kiln for ceramic production often found in southern China.
Usually built along the steep slope of a hill, the kiln spreads long and thin upward, like a dragon crouching on the hill, with its head at the bottom and tail tilting at the top.
Qianshu Dragon Kiln is 43.5 meters long and sits on a human-made slope. Inside is a long-arched tunnel space with 42 holes on either side, through which firewood is thrown in. On the western side are five larger holes where people step in to place objects needing to be baked, the entrances so small that a grown-up needs to bend down to get in.
Fire is lit from the bottom, where the dragon head was supposed to rest. When it is not in use, a small pool of water is always kept.
“Folklore has it that the dragon delights in having a bit of water near its head,” Zhao says.
Since the 1970s coal has been used in the lighting process, but the main fuel is always firewood, preferably pine or bamboo. A keen watch needs to be kept on the kiln day and night, with fuels being fed to it constantly to keep the fire burning at full power for 40 hours. The temperature in the kiln can be as high as 1,200 C.
Workers invented a special stool, with its feet cut to fit its tilting positioning along the slope, enabling them to sit down for a rest during the long working hours spent near the fire.
“These stools are a trademark of the unique practice of Yixing ceramic making,” Zhao says at the entrance of an exhibition hall by the Qianshu Dragon Kiln. Dozens of wooden stools with tilted feet are placed on the wall near the gate, greeting visitors.
Teapots and other objects are placed in protective boxes before they are baked in the kiln. These rough clay boxes can be used no more than five times before they crack and have to be discarded.
The fuel and human power costs are much higher than what modern electricity kilns require. In addition, the success rate is much lower, Zhao says, pointing at a defective urn with glaze dripping on the side.
“In a traditional wood-burning kiln the temperature is not strictly under control, so sometimes accidents happened, and the dancing ash caused imperfections on large jars and urns unprotected by the boxes.”
Even when it is used, “Qianshu Dragon Kiln now produces mainly daily utensils such as urns, jars, pots and so on”, Zhou Xiaodong, director of the China Purple Clay Museum and Yixing Ceramic Museum, wrote in an essay on ancient ceramic making in the area.
The kiln “well preserved the structure and processing method for ceramic production in ancient China”, he said in the essay.
“It is a rare and precious object for the research of ceramic history in Yixing.”
Dragon Kiln, or Long Yao, is a unique type of kiln for ceramic production often found in southern China.
Qianshu Dragon Kiln now produces mainly daily utensils such as urns, jars, pots and so on, … well preserved the structure and processing method for ceramic production in ancient China, … It is a rare and precious object for the research of ceramic history in Yixing.”
Zhou Xiaodong, director of the China Purple Clay Museum and Yixing Ceramic Museum
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-toWeihe 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.