Chasing Green and Connecting Mountains and Seas to Connect the Heavenly Trench (Economic New Direction · Major Engineering Frontline)

The train passes through the Yingpan Qingshui River double track super large bridge of the Guinan high-speed railway.

Photo by Yang Wenbin, journalist from Xinhua News Agency

On August 31st, the entire Guinan high-speed railway line was officially opened for operation.

How difficult is it to build a high-speed railway between Guiyang, Guizhou and Nanning, Guangxi?

High mountains stretch across, and rugged mountains crisscross - the bridge tunnel ratio is as high as 90%, with a total length of 482 kilometers, and even bridges need to be built in tunnels.

The Guinan high-speed railway, a world heritage site and an emerald on Earth, must pass through multiple nature reserves. Every piece of soil and every green plant cannot be disposed of arbitrarily.

No matter how difficult it is, it must be built.

The Guinan high-speed railway connects more than 30 ethnic minority settlements along the line, ending the history of multiple areas without high-speed rail and bringing new development space.

How was such a super project built, with a total investment of over 75 billion yuan in the past 10 years from exploration to opening to traffic?

Recently, the reporter followed the footsteps of Long Zongming, the overall design leader of the Guinan high-speed railway, Xu Weinong, the on-site commander of the Guizhou section, and Wang Xuguang, the chief engineer of the Chaoyang Tunnel, to explore the truth.

Overall Design Director Long Zongming:

"The design scheme has undergone thousands of changes, only to achieve the best balance between development and protection."

Guiyang and Nanning are important nodes on the western land sea new corridor. Opening up land transportation channels between the two regions is not only necessary for local economic development, but also for the construction of the main channel of the western land sea new channel.

In 2014, the exploration work for the Guinan high-speed railway was launched.

Looking at the map, Guiyang and Nanning span across the Guizhou Plateau, Miaoling Mountains, as well as multiple rivers such as Qingshui River and Zhangjiang River. Along the way, there are high mountains, deep valleys, and crisscrossing gullies, with complex and varied terrain and landforms.

The route is the runway of the high-speed railway. The geological conditions are so complex that route selection is crucial.

"The design of a high-speed rail line, safety and reliability are the bottom line, and serving local development is the goal." said Long Zongming from China Railway Eryuan. The first step is to select suitable construction sections from complex geology.

The new technologies of "space, sky, and earth" exploration are all on the rise. Space refers to the use of satellite remote sensing and other technologies to interpret unfavorable geology; Tian refers to the use of drones and other technologies for survey and design, avoiding unfavorable geology and unnecessary construction sites; Ground refers to understanding geological parameters through technologies such as geological compasses and ground LiDAR. "High resolution satellite remote sensing interpretation technology has greatly improved the accuracy and efficiency of interpreting unfavorable geology," said Long Zongming.

With basic information and preliminary design implementation, the specific route of the line still depends on on-site visits by design personnel.

Long Zongming recalled that in September 2015, in order to determine the entrance and exit of the Old Baishan Tunnel, a team of five people spent several days exploring in the mountain ditch, walking wild roads, crossing small rivers, and wading through accumulated water, before finally choosing the location of the tunnel entrance. "We walked through the 482 kilometer high-speed rail line step by step, and there was no way out." Two months later, Long Zongming and the design team members walked from the starting point to the endpoint.

The more difficult aspect in design is the balance between development and protection.

Libo County, Qiannan Buyi and Miao Autonomous Prefecture, Guizhou Province, is a world natural heritage site and is known as the "emerald on the belt of the earth.". "There are many nature reserves here, and the best choice is to surround them from the outside," said Long Zongming. However, in order to maximize the benefits of tourism resources and better promote the economic development of local areas along the high-speed railway, the route also needs to pass through Libo County. What should we do?

Replacing bridges with tunnels and roads with bridges. After a year of repeated argumentation and environmental impact assessment, the Li band line was finally determined.

"It took us a whole three years to determine the entire route plan," said Long Zongming. The Guizhou section alone had a route plan of 1675 kilometers, selecting the most suitable 199.64 kilometers. "A high-speed rail line has undergone thousands of design changes, only to achieve the best balance between development and protection.".

The design plan aims to pass through more areas with relatively backward transportation infrastructure as much as possible, allowing more than 30 ethnic minority settlements to leap into the era of high-speed rail.

Xu Weinong, the on-site commander of the Guizhou section:

"We have built high standard high-speed rail lines under the most stringent environmental requirements."

Seeing Xu Weinongshi, the Guinan high-speed railway is undergoing a comprehensive high-speed inspection train called "Dr. Huang". On that day, a train with a body painted in eye-catching yellow passed through the Guizhou section of the Guinan high-speed railway at a speed of 385 kilometers per hour, and all indicators of the line were tested to the limit.

"For engineers, the lines are like their own children. This inspection is like a child taking the college entrance examination." Xu Weinong, from the Guizhou Company of the Shanghai Kunming Passenger Dedicated Line, is the on-site commander of the Guizhou section.

In the view of the "old railway" who has worked for 40 years, the biggest feature of Guiyang Nanning High speed Railway is green.

——The Guinan high-speed railway has withstood the most rigorous environmental test with a hole in the emerald.

In 2018, the construction of the entire Guinan high-speed railway began. The 90000 Dashan No.1 Tunnel is one of the most concerning projects for Xu Weinong.

On the one hand, the engineering difficulty is high. The tunnel body passes through 9 sets of strata, 3 faults, and 2 contact zones between soluble and non soluble rocks. It crosses regional underground rivers and numerous karst depressions, making it prone to mud bursts, water inrush, and landslides.

"Within a 7-kilometer radius of the tunnel exit, there are 34 karst sinkholes, of which 19 pose a threat to construction and 1 is located directly above the tunnel." Xu Weinong explained that the maximum daily water inflow of the tunnel is 720000 cubic meters, which is equivalent to the storage capacity of 380 standard swimming pools, and the risk is extremely high.

On the other hand, environmental protection requirements are higher. The excavated soil from the tunnel must be transported and piled up 15 kilometers away; The transverse tunnel excavated for construction must be backfilled and greened to keep the same appearance; Power supply stations and traction substations cannot be built on the edge of the line and must be moved outside the protection zone

The construction party specifically spent 10 million yuan to build three sewage treatment stations to ensure that the discharged wastewater meets environmental protection requirements. "The monthly operating cost of the treatment station alone is as high as 100000 yuan, but we have achieved that the wastewater can be recycled and has no impact on the environment," said Wang Ping, Deputy Manager of the Project Department of China Railway 18th Bureau, a tunnel construction unit.

"We have built high standard high-speed railway lines under the strictest environmental requirements," said Xu Weinong.

——Spend an additional 38 million yuan just to minimize the impact on organisms.

The Chengjiang Double Line Grand Bridge crosses the Chengjiang National Wetland Park in Du'an, Guangxi. This is a conservation area where 22 species of national level II key protected animals, including the small crow azaleas and black winged kites, live. These animals are particularly sensitive to noise and light.

"We have specially designed sound and light barriers, which cost an additional 38 million yuan, just to minimize the impact on the biodiversity in the park," said Long Zongming. In actual construction, the construction unit also scientifically increased the bridge span and protected 2291.94 square meters of wetlands by using the "environmental equation" of increasing the pier spacing and reducing the number of piers through actuarial calculations.

The Guinan high-speed railway passes through 10 natural reserves, 2 World Heritage sites, 13 urban drinking water sources, and 7 forest parks along the route. The construction process achieves zero pollution and zero damage, making it an ecological railway.

Wang Xuguang, Chief Engineer of Chaoyang Tunnel:

"For this tunnel, our youth is spent in this big mountain."

"This tunnel is the most complex super large karst tunnel with rich water along the entire line, which is very difficult." Xu Weinong suggested that the reporter must go to Chaoyang Tunnel to take a look.

After crossing mountains and ridges for nearly 4 hours, the reporter finally arrived at the Guiyang South High speed Railway Project Department of China Railway 12th Bureau. The driver told the reporter that there was no road here, and it was specifically built to dig a tunnel.

The Chaoyang Tunnel, with a total length of 12734 meters, consists of over 70% of the entire tunnel due to fractured fault zones and weak surrounding rocks, and carries 135 construction risks. The underground rivers and giant karst caves crisscross the mountain, and the surface water and groundwater are interconnected, resulting in an extremely complex geological environment.

"The Chaoyang Tunnel is truly a 'water curtain tunnel', which can discharge water from West Lake in 10 days," said Wang Xuguang from China Railway 12th Bureau. Even more dangerous is that the tunnel is buried more than 432 meters deep. This means that once the karst water inside the mountain is punctured during construction, the water can spray 15 meters away under enormous mountain pressure, and the pebbles mixed in the middle will fly out like bullets.

Faced with high-pressure water rich and karst geological problems, builders have constructed a tunnel construction pattern of "2 horizontal tunnels+1 inclined shaft+2 horizontal guide+1 ventilation shaft+17 horizontal channels", solving the problem by constructing drainage tunnels exceeding 10000 meters.

"We entered the construction site at the end of 2016 and did not connect until May 2022," said Wang Xuguang. "For this tunnel, our youth is spent in this big mountain."

During the construction process, there are still many such projects. More than 100000 people participated in the construction of the Guinan high-speed railway.

All of this is worth it.

"We look forward to the Guinan high-speed railway bringing more tourists to experience the 'natural oxygen bar', while taking tea out of the mountains to help tea farmers increase their income and become prosperous." Meng Rongfang, a representative project of intangible cultural heritage and a state level inheritor of the production technology of Duyun Maojian tea, said.

After its opening and operation, the Guinan High Speed Railway is connected to Shanghai Kunming High Speed Railway, Chengdu Guiyang High Speed Railway, Chongqing Guiyang High Speed Railway, Guiyang Guangzhou High Speed Railway and other lines through the Guiyang Railway Hub. It is also connected to intercity railways between the Beibu Gulf urban clusters such as Nanning Guangzhou High Speed Railway, Nanning Beihai, Fangchenggang, and Chongzuo through the Nanning Railway Hub.

The mountains and seas are connected, integrated into the national high-speed rail network, and the transportation artery in the southwestern ethnic areas has been opened up.