Zhongxin Network Yuxi November 25 Title: The opening of the China-Laos Railway is imminent, and the builders recall the days of tunneling in the "water tofu"
Reporter Miao Chao
The China-Laos Railway is about to open in December this year, and the reporter recently visited the Xinping Tunnel of the Yuma Railway in the China section of the China-Laos Railway, which was once a Class I high-risk tunnel and a "card neck" project of the China-Laos Railway, which was called by the builders as a tunnel in the "water tofu".
Today, the Xinping Tunnel has been laid and the railway tracks have been completed, quietly waiting for the opening of the China-Laos Railway. At that time, the 160 km/h train will pass through the 15 km long Xinping Tunnel in just 6 minutes. But for these 6 minutes, the builders stubbornly played with geological disasters such as water gushing, mud, sand gushing, and slump for more than 1500 days and nights.
"It's like punching a hole in 'water tofu'"
Xinping Tunnel is located in Xinping County, Yuxi City, Yunnan Province, between the lofty mountains, down through Mopan Mountain, the tunnel has a total length of 14.835 kilometers, through a total of 6 fault fracture zones, so including water inrush, mud, sand surge, large deformation and other undesirable geological disasters occur frequently.
The picture shows that during the construction of the Xinping Tunnel, the mud burst rushed the construction equipment tens of meters away (data map). Courtesy of the Yumo Railway Project Department of China Railway Tunnel Bureau
In October 2018, the reporter visited the Xinping Tunnel, which is under construction, and the tunnel is hot and humid more than 350 meters above the surface, and the walls of the cave are full of thin pipes, and yellow mortar gushes out of the pipes and falls on the ground to form a thick layer. At that time, the reporter grabbed a lump of fine sand on the ground, grabbed it with his hand, and water oozed out of his fingers, and when he pinched his fingers, the fine sand became powder.
"Tunnel construction is afraid of soft and hard." Zhou Kunpeng, manager of the second branch of the Yumo Railway Project of the China Railway Tunnel Bureau, told reporters, "The water content of the sediment is up to 28%, so the description is too abstract? For example, digging a tunnel under such geological conditions is like punching a hole in 'water tofu'. ”
What does it look like to punch a hole in "water tofu"? From the several mud and sand surges that occurred in the Xinping Tunnel, we can get a glimpse of it:
On January 21, 2017, Gou Bo, the captain of the No. 3 horizontal hole shelf, organized personnel to carry out advanced support. Suddenly, the seepage on the right side of the vault increased and became cloudy. Intuition tells Gou Bo that danger is coming. He quickly organized the rapid evacuation of operators and machinery. After 10 minutes, the palm surface appeared to fall into pieces, and with the sound of "rumbling...", more than 4,000 pieces of sediment gushed out.
The picture shows the operators braving the "pouring rain" operation (data map). Courtesy of the Yumo Railway Project Department of China Railway Tunnel Bureau
On March 7, 2017, Huang Wenhua, who was on duty at The Second Horizontal Cave, noticed a small number of small black mud clip stones gushing out from the right side of the palm face, and experience told him that danger was coming, and he ripped open his voice and shouted, "Danger, all evacuate!" In less than a quarter of an hour, the mud rushed out with lightning speed. Huang Wenhua, who stayed behind to observe, before he could react, was washed out of the mud more than 30 meters away. Huang Wenhua tried his last bit of strength to climb to the mouth of the cave. The anxiously waiting workers outside the cave hugged and wept with the "clay man" Huang Wenhua.
On October 6 and 7, 2017, the mud protruding from the No. 3 horizontal hole once again poured out separately. Two days later, relatively stable, Li Ping, project manager of the Yumo Railway 3 bid of China Railway Tunnel Bureau, and Zhou Kunpeng, manager of the second division, climbed the high-pressure feng shui pipe and moved into the No. 3 horizontal hole little by little. The scene was a mess: the sediment poured into the auxiliary tunnel for more than 130 meters, buried more than 1 meter thick, and the construction bench together with the two masonry trolleys weighing more than 120 tons was washed out by the sediment for tens of meters.
In addition to the mud and sand, the daily influx of water in the Xinping Tunnel is maintained at more than 20,000 cubic meters, and the operators brave the "pouring rain" every day, and even paddle rubber boats in the tunnel that has become a river, and there will be small stones falling on the top of the palm surface from time to time, and the danger is self-evident...
The picture shows that after the inrush, the tunnel became a river (data map). Courtesy of the Yumo Railway Project Department of China Railway Tunnel Bureau
Li Ping, project manager of the Yumo Railway of China Railway Tunnel Bureau, pulled his finger and counted the details: Since the construction of the Xinping Tunnel, there have been 41 surges, with a surge volume of more than 67,000 cubic meters, 417 collapses, more than 57,000 cubic meters of collapses, a deformation length of 2,150 meters, and a total of more than 120,000 yuan of mud and rock flows in the cave, equivalent to the volume of a 30-story building of 4,000 square meters per floor, the maximum settlement of the tunnel is 1,000 mm, and the maximum convergence is 680 mm...
A set of icy data is a silent annotation of the Xinping Tunnel's passage through six fault fracture zones. But the reporter clearly remembers that at that time, Li Ping said calmly and firmly, "No matter how difficult the road ahead is, we just want to cross this majestic road!" ”
"Innovation is our only option"
After three years, the reporter is looking forward to returning to the bottom of Mopan Mountain, the straight rails have been paved into the Xinping Tunnel, and the tunnel walls made of reinforced concrete are strong and smooth. While quietly waiting for the opening of the China-Laos Railway, the builders told reporters how they opened the Xinping Tunnel in the "water tofu".
The picture shows the scene during the construction of the Xinping Tunnel (data map). Photo by Miao Chao
"The construction of complex soft rock geology has no rules to follow, which has subverted the traditional experience of many tunnel engineers for a lifetime, and also changed my perception of railway construction in the past 12 years." Zhou Kunpeng pointed to the design drawing of the Xinping Tunnel and told reporters, "In the face of the collapse of weak geological sections, large deformation of surrounding rocks and safety risks, innovation is our only choice, both technically and in terms of management." ”
Through comparative analysis, the project department creatively adopted the three-step reserved core soil belt arch excavation method to effectively control the problem of continuous deformation. Later, the three-step arch excavation method was promoted in the construction of the whole line tunnel of Yumo Sanbiao, which achieved remarkable results and provided valuable experience for the safe construction of railway tunnels.
Forward, surge, go backwards, clean up, move forward again... In the game with complex geology, in the 4 years of construction of Xinping Tunnel, the project department combined with complex geology to develop a fully supporting integral mobile trestle, variable section formwork trolley, steel arch locator, grouting quick joint and other 7 national utility model patents, these patents have become a "weapon" to improve construction efficiency.
The picture shows that the Xinping Tunnel has been completed, quietly waiting for the opening of the China-Laos Railway. Photo by Miao Chao
In order to stimulate everyone's innovation power, the project department according to the actual situation, in order to improve the construction quality, reduce energy consumption, improve efficiency and personnel quality for the purpose, develop a mass technical creation of new goals, implementation plans and safeguard measures, not only for the high technical content, construction difficulty of the project to carry out scientific and technological research, but also around the adaptability of construction and production, reliability, economy to carry out the "five small" activities with "small inventions, small creations, small innovations, small designs, small suggestions" as the main content, Fully tap the creative potential hidden in the majority of employees.
On April 26, 2020, after nearly four years of hard work by the builders, the Xinping Tunnel, a key control project of the China-Laos Railway, was broken. The safe and scheduled breakthrough of this tunnel not only resolves safety risks for the whole line, but also creates conditions for subsequent bridge erection and track laying, and provides a guarantee for the completion and opening of the entire line of the China-Laos Railway on schedule.
"In those four years, as long as it is a favorable idea for construction, we encourage everyone to try boldly and bravely challenge." Today, Wang Qingjian, chief engineer of the Yumo Railway Project of China Railway Tunnel Bureau, recalled the whole process of Xinping Tunnel construction, saying, "Innovation is the first productive force of Xinping Tunnel, but compared with product innovation, it is more important to stimulate everyone's awareness of innovation and the spirit of innovation." (End)
Source: China News Network