Chengdu-Guizhou high-speed railway is an important part of China's "eight vertical and eight horizontal" high-speed railway network Lanzhou to Guangzhou channel, starting from Chengdu, Sichuan, as for Guiyang, Guizhou, the line is 648km long, the design speed is 250 kilometers per hour, the maximum slope is 30, known as "the world's first mountain high-speed railway". On December 16, 2019, the Chengdu-Guizhou high-speed railway was officially put into operation, and Bijie, Guizhou Province has since entered the era of high-speed rail.
Wumeng is full of good scenery, hidden in the depths of the boudoir people do not know". Bijie, which has a beautiful scenery but is constrained by traffic conditions, can only hide in the deep mountains for a time. Therefore, the construction of a railway has become the wish of the people of Bijie. In terms of construction significance, the opening of the Chengdu-Guizhou high-speed railway has multiple significance for shaping the economic pattern. From the perspective of the province, after the opening of the Chengdu-Guizhou high-speed railway, it will directly shorten the time and space distance between the regions along the line, which is of great significance for Sichuan to build a new regional development pattern of "one trunk and multiple branches, and five districts synergy". From outside the province, after the opening of the Chengdu-Guizhou Railway, it will connect the Guizhou-Guangzhou high-speed railway and the Guinan-Guizhou high-speed railway under construction, forming a high-speed railway channel leading to the Beibu Gulf Economic Zone and the Guangdong-Hong Kong-Macao Greater Bay Area. Yunnan, Guizhou and Sichuan are more closely connected, and Sichuan, the Beibu Gulf Economic Zone and the Guangdong-Hong Kong-Macao Greater Bay Area will form a seven-hour economic circle. This will further promote the formation of a new trend of "four-way expansion and global opening-up" in our province, expand opening up and cooperation with countries along the "Belt and Road", cultivate new advantages of opening-up, and expand new space for development. From a national point of view, the further increase in the number and mileage of high-speed corridors in inland areas such as Sichuan and Guizhou, as well as in coastal areas, will drive the opening up and development of inland areas in the west, and then promote the formation of a new pattern of coordinated development of land and sea and east-west parallel development across the country. On the one hand, it will further strengthen the economic and social ties between the two regions, promote the opening up of the western inland region, and promote the opening up and development of the western inland region. On the other hand, it will also contribute to the formation of a pattern of overall land and sea opening up across the country. 
The many tests reveal the difficulties in the construction of the Chengdu-Guizhou high-speed railwayDue to the complex geological conditions along the way, a lot of time was spent on survey and construction during the construction process. In particular, the seven points of Jinsha River Bridge, Shangheba Tunnel, Nanguang River Double-line Bridge, Xiangba River Bridge, Jiaonan River Bridge, Luojiahe Bridge and Xixi River Bridge are all major and difficult projects, and they are all great tests for design and construction. The railway construction army tried to break through this "railway exclusion zone". Chengdu to Guiyang high-speed railway Xixi River Bridge is located in Bijie City, Qianxi City and Dafang County junction, across the 260-meter-deep Xixi River Gorge, is China's high-speed rail concrete steel tube rotating arch bridge, its world-class technical difficulty, in the history of China's high-speed rail bridge can be called unique. The total length of the Xixi River Bridge of the Chengdu-Guiyang high-speed railway is 4936 meters, the highest pier is 60 meters, the depth from the bridge deck to the valley floor is 260 meters, and the new structure of the top-supported concrete-filled steel tube arch bridge with a span of 240 meters is adopted. The bridge has set three records for the largest span, the heaviest rotating weight and the first "tractor-type over-arch thrusting method" for China's high-speed rail rotating bridge, which has accumulated successful experience for the scientific research and construction of special structure bridges in China, and also created favorable conditions for the completion and opening of the Chengdu-Guiyang high-speed railway as planned. The project is the first time in China that the high-speed rail double-line passenger dedicated adopts the new technology of "extremely asymmetrical two-way horizontal rotation", and the main arch of the bridge is rotated by 133 degrees and 120 degrees on both sides of the canyon respectively to achieve docking and closing in the air, and the rotating weight is 140,000 tons is the largest of the same type of bridges in China. During the construction, the "drag-type over-arch jacking method" was used for the erection of the beam structure, and the main arch deformation and pier cracking on the arch that may occur in the process of jacking and slipping were successfully avoided through GPS satellite positioning monitoring and other technical means, so as to achieve accurate jacking in place. In the process of construction of the Chengdu-Guizhou high-speed railway, there are many representative cases of innovation. For example, the Yachi River is located in the upper reaches of the Wujiang River, which is the throat artery between Bijie and Guiyang in Guizhou. The Yachi River Bridge is located about 8 kilometers upstream of Suofengying Hydropower Station in Guizhou Province, the bridge starts from Mixinzhai, Tieshi Township, Qianxi County, crosses the Yachi River to the southeast, and ends at the Langshang Group of Shatian Village, Undercurrent Township, Qingzhen City. The bridge site is a typical karst plateau and canyon landform type, the terrain on both sides of the river is steep, and the angle between some rock cliffs and the river surface reaches a degree. According to Mei Xinyong, deputy chief engineer of China Railway Bridge Institute Group, in the design process, after scientific calculations and repeated demonstrations, the bridge scheme of the medium-bearing hollow steel-concrete basket arch bridge was innovatively proposed. The bridge is designed as a double-track railway bridge, with a line grade of passenger dedicated line and a designed maximum speed of 250 kilometers per hour. The Yachi River Bridge has three characteristics: large span, novel structure and high pier. Large span: The bridge adopts a 436-meter medium-bearing steel-concrete combined arch bridge, which is a long-span mountain railway bridge. Novel structure: the structure for the first time to adopt steel-concrete combined arch structure, for the first time in the world, can make full use of the characteristics of the combined structure, save materials, make the structure stress simple and reasonable, at the same time can reduce the construction process, convenient construction. Pier height: The T-frame piers on both sides of the main bridge are up to 70m, which belongs to the high-pier railway bridge. 
Tunnels account for more than 8 percentThe construction in the complex terrain of karst landform has brought a lot of challenges to the builders, because of the large altitude span and many bridges on the whole line, this high-speed railway is called the high-speed railway on the cloud. This "high-speed railway on the clouds", the altitude spans from more than 200 meters in the Sichuan Basin to more than 2,000 meters in the Yunnan-Guizhou Plateau, the topography along the line changes drastically, the geological conditions are extremely complex, with "more mineral deposits, more goafs, more natural gas, geological structure development, karst development, gravity poor geological development, salt rock development" and other "three more, four development" characteristics, high-speed rail construction is extremely difficult. In order to overcome these problems, "replacing the road with bridges" and "replacing roads with tunnels" have become the main construction methods of Chengdu-Guizhou high-speed railways, and the tunnels in the Yunnan-Guizhou section are particularly concentrated, so the tunnel design and construction are unprecedentedly difficult. The large altitude difference makes the line rise and fall greatly, often going down the slope to the bottom of the ditch, and then starting to climb up again to adapt to the complex terrain along the line. In the basin area, the average height of the bridge is about 20 30 meters, and in the Yunnan-Guizhou Plateau, the average height of the bridge soars to 70 80 meters. The Yujingshan Tunnel, known as the "first hole of high-speed rail" in the industry, has a total length of 6,306m and is located in Weixin County, Yunnan Province, with a design speed of 250km per hour double-line tunnel, which is a full-line control project. During the construction of the cave body revealed a huge karst cave and dark river system, along the line length of 95m, perpendicular to the line width of 230m, height of 50 120m, karst cave volume of 1.08 million square meters, equivalent to 480 standard swimming pool volume, the bottom of the development of a large dark river, the width of the river surface 10 15m, the rainy season flow of 70m s, the dark river water surface to the track surface height difference of 120m, the dark river is the only water source of the downstream hydropower station. After 10 months of program research, 5 expert reviews, and hundreds of on-site meetings, ......Finally, the karst cave treatment plan of Yujingshan Tunnel was released. The technicians decided to complete the final section of the tunnel by digging a hole in the cave and building a bridge in the hole. At the same time, for the first time, the construction team adopted a low-prestressed fully cohesive anchor cable structure on the roof of the karst cave of the high-speed rail tunnel to make the roof of the karst cave more stable. For the first time, a large-section lining structure was constructed in the tunnel karst cave accumulation and backfill strata, and a large-section tunnel structure with a height of about 8 floors was constructed in the loose slag body, creating a new method of tunnel construction under complex geological conditions. For the first time, the measures of compensating grouting to control the total settlement and differential settlement during the operation of the high-speed railway tunnel treatment were adopted, and the conditions were reserved in the tunnel, and the compensation and reinforcement could be carried out at any time according to the settlement situation, so as to ensure the safety of the tunnel during operation. Through step-by-step fine design, the karst cave problem was successfully handled, so that the bridge in the Yujingshan Tunnel reached the settlement standard and ensured the stability of the bridge in the tunnel. 
The whole line bypasses 87 ecologically sensitive areasChengdu-Guizhou high-speed railway is the first railway in China designed in accordance with the "Guidelines for the Construction of Green Channels for Railway Projects" issued by China National Railway Group, and is the first green mountain railway in China, which embodies the design concept of green environmental protection in terms of green ecological protection, natural environmental protection and prevention and control of soil erosion. During the construction of the Chengdu-Guizhou Railway, 87 ecologically sensitive areas were avoided along the entire line. In the lower reaches of the Minjiang River, there are 90 kilometers of rivers that belong to the national nature reserve of rare and endemic fish in the upper reaches of the Yangtze River, and the construction of bridges will interfere with them if there are too many piers. The Caiba Minjiang double-line bridge in Yibin has created a number of "China's best" to protect these rare fish. The bridge spans the Minjiang River and is more than 1,000 meters long. In order to reduce the piers in the water and reduce the impact on the protected area, after more than 3 years of demonstration, the bridge creatively adopts the steel truss continuous beam with a maximum hole span of 224 meters, becoming the largest span steel truss continuous beam bridge in China and the first steel bridge in China with a variable truss height main truss structure type with a lower chord curve. It is reported that the Chengdu-Guizhou high-speed railway has also made great efforts in energy conservation and emission reduction, taking vibration and noise reduction measures such as sound barriers, soundproof windows, and functional replacement, using energy-saving autotransformers in the traction power supply system, using large-span grid structures with economical steel consumption in the station building, and selecting thermal insulation materials to reduce energy consumption, so as to realize the environmental protection management of the whole life cycle of the railway. Because of the advanced energy-saving measures, only the section from Leshan to Yibin can save 710,000 kWh of electricity per year, which is equivalent to saving about 284 tons of standard coal and reducing carbon dioxide emissions by 7075 tons, reducing carbon emissions by 194 tons, reducing dust emissions by 194 tons, and reducing sulfur dioxide emissions by 22 tons.
Text: Han Jing. 