When you ride the subway swiftly through every corner of Changsha, you may not know that it is precisely because of an 80-meter-long "underground dragon" gnawing through soil and mud that these tunnels leading passengers in all directions now exist.
For the first stop of this grassroots visit, the author walked into the workshop of CRCC Heavy Industry in Xingsha, a company that has been listed among China's Top 100 Machinery Industry Enterprises for three consecutive years and has won the fifth "Hunan Provincial Governor Quality Award." In the factory building within the national-level Changsha Economic and Technological Development Zone, shield machines produced locally in Hunan are being assembled at a rate of 4 units per month, making a remarkable contribution to Hunan's economic and social development, especially infrastructure construction and the equipment manufacturing industry.
Four Units Assembled Per Month
At CRCC Heavy Industry Group, No. 88 Dongqi Road, Changsha Economic and Technological Development Zone, there are five factory buildings. In the Phase II assembly workshop, six shield machines are parked, either undergoing final assembly or being disassembled. At 2 p.m., the outdoor temperature is still low, but the spacious workshop is warmed by occasional welding sparks.
The shield machine body is mostly about 80 meters long—the front cutterhead rotates to crush rock or soil, while the rear body transports the debris out and installs concrete segments around the tunnel. Once it passes, a tunnel is formed. Thanks to this underground dragon, each section of the Changsha subway where excavation starts can be completed at an average speed of 9 meters per day.
Feng Xunshi, born in 1990, wearing a bright red CRCC Heavy Industry work uniform, patrols back and forth in the workshop. He is the foreman of the second assembly team at the company's general manufacturing plant. He introduced that from parts procurement or self-production to final assembly into a finished product, then debugging and delivery acceptance, 56 workers can complete 4 shield machines per month.
Four Updates and Iterations Completed
"The shield machines currently used in the Changsha subway are already our fourth version," said Chen Qingbin, director of the Earth Pressure Balance Shield Research Institute of the Tunneling Machine Research Institute under CRCC Heavy Industry's Tunneling Machine Business Division, pointing to other similar shield machines in the workshop. "Some updates are due to geological reasons, some due to construction needs, and others due to on-site personalized operation requirements."
Chen Qingbin explained that early Changsha had relatively uniform geological conditions, and one type of machine could basically handle them. As more subway lines started construction, the geological conditions encountered became more complex—some required drilling through hard rock zones, some needed to pass through karst caves, and others required crossing rivers beneath riverbeds with abundant water...
Different strata correspond to different cutterhead requirements. After winning an order, they design the performance of the main cutterhead specifically, and at the same time, within the whole machine, they try to meet the engineering requirements as much as possible. Since the Changsha subway first used the machines in 2010, the now-operational Line 2 and Line 1, as well as Lines 3, 4, and 5 currently under shield construction, have successively used more than 80 shield machines produced by the company.
Capturing Half of the Domestic Market
The shield machine market was once dominated by foreign brands for a long time. Chen Qingbin still remembers the scene when he graduated and went to negotiate orders: "The buyer directly held foreign technical standard drawings and asked us if we could meet them."
Today, CRCC Heavy Industry has captured half of the domestic shield machine market, and in the field of large-diameter shield machines over 6 meters, it has reached an 85% market share. Three years ago, the first domestic large-diameter full-face hard rock tunnel boring machine (open TBM) with independent intellectual property rights, crowned the "King of Tunneling Machines," rolled off the production line at the company, once again filling a domestic gap and marking a major breakthrough for China in the field of large-scale high-end equipment manufacturing.
Behind each breakthrough are the day-to-day persistence and dedication of people like Chen Qingbin. Having come to Changsha from Heilongjiang nearly 9 years ago, Chen Qingbin has not yet climbed Yuelu Mountain.
Half a month ago, CRCC Heavy Industry's Heavy Equipment Industrial Park, covering an area of 1,700 mu, broke ground about 16 kilometers from the workshop. Liu Feixiang, Party Secretary and Chairman of CRCC Heavy Industry, said in his speech: "We will help Hunan continue to strengthen, optimize, and expand the rail transit and equipment manufacturing industries."
New Year's Wishes
Every Spring Festival, the last person to leave the department puts a seal on the office door. Chen Qingbin has fulfilled this "important task" for 9 years. When asked about his New Year's wishes, Chen Qingbin smiled shyly: "In the past, I didn't spend much time with my family. I hope to have more time to accompany them!"