Three major technical problems of the Qinghai-Tibet Railway and their solutions
The Qinghai-Tibet Railway is the highest plateau railway with the longest route in the world. The Tanggula Mountain Railway has a maximum altitude of 5,072 meters, a section above 4,000 meters for 960 kilometers, and a continuous permafrost layer of more than 550 kilometers. It is one of the most arduous projects among the four major projects in my country's implementation of the Western Development Strategy. When building a railway on the Qinghai-Tibet Plateau, the geological conditions are complex, the engineering is difficult, and the environmental protection requirements are high. Therefore, the Qinghai-Tibet Railway is also the most technically difficult project among the four major projects. Permafrost, alpine hypoxia, and environmental protection are the three major technical problems restricting the Qinghai-Tibet Railway. Recently, with the joint efforts of scientific research and engineering technicians from the Chinese Academy of Sciences, the Academy of Railway Sciences, the railway construction department and relevant universities, three major problems have been successfully solved. The Qinghai-Tibet Railway is paving 25 meters every 2 minutes and building bridges 6.5 times a day. hole, with an average daily track laying speed of 3,000 meters extending towards Lhasa. ?The Qinghai-Tibet Railway has a total length of 1,142 kilometers and is completed in three sections. What was built in Qinghai in 2002 was the Wangkun (Kunlun Pass)-Wangtang (Tanggula Pass) section with the most complex geology and technical difficulties on the Qinghai-Tibet line, with a total length of 410 kilometers. There are ten key projects in this section, namely six bridges (Sancha River Bridge, Xueshui River Yangtze Source Bridge, Qingshui River Bridge, Bufrost Spring Bridge, Chumar River Bridge, Bala Bridge Caiqute Bridge); two tunnels (Fenghuoshuo Tunnel, Kunlun Mountain Tunnel); two roads (Wangkun-Bufrog Spring frozen soil roadbed; Bufrozen Spring-Chumal River frozen soil roadbed). Among these ten major projects, the three major technical problems are also the most concentrated and prominent. Scientific researchers and technicians have effectively solved three major technical problems through field studies on the Kunlun Mountain Tunnel, Fenghuoshan Tunnel, etc., as follows: 1. Permafrost problem? When building roads on frozen soil, the roadbed will have different characteristics as the temperature changes. instability. Due to the great annual temperature changes on the Qinghai-Tibet Plateau, the highest temperature in summer is 38°C and the lowest temperature in winter is -40°C. In seasons with high temperatures, the permafrost melts, forming thermal lakes and underground rivers. The roadbed slurries and slides, forming a washboard road. When the temperature drops, the roadbed freezes or even expands abnormally, forming frost-swollen balls. Among the frozen soil, there are soil-bearing ice layers, ice-saturated frozen soil, fissure ice, sandstone, mudstone, and interbedded silt. The temperature rises, resulting in the expansion of thermal melt, especially when excavating open tunnels. The slope becomes unstable, collapses, and the base becomes muddy. After tunnel excavation, the arch will seriously fall off or even collapse. After the tunnel is put into operation, it will suffer from repeated freezing and thawing. Destroy structures and affect operational safety. After the railway is opened to traffic, a large amount of waste heat will be discharged from the train, which will have an impact on the railway roadbed. In order to solve the problem of frozen soil, experts have adopted the following methods to ensure the stability and durability of the roadbed: ?1? Use rubble ventilation roadbed, rubble ventilation berms, lay insulation materials, and use hot rod technology. (Ventilation roadbed and ventilation berms make air convection faster, making the roadbed temperature consistent with the surrounding air temperature, making it difficult to form local hot zones, which is beneficial to the stability of the roadbed). 2. Use bridges instead of roads in frozen soil and unstable places (build bridges on frozen soil, there is no water underneath but unstable frozen soil), such as the Qingshui River Bridge. 3. For tunnel projects, a waterproof and thermal insulation layer is installed in the lining. 4? Re-research and formulate technical standards for concrete durability to improve the durability of concrete structures. In order to prevent the thermal expansion and contraction from causing moire on the bridge piers and bringing the concrete into "close contact" with the frozen soil, negative temperature health care measures are adopted. In the summer, well digging cooling and ventilation cooling measures are adopted to keep the temperature at about 10 degrees. In the winter, heating is adopted. , add antifreeze, wrap quilts on bridge piers and other measures to ensure the durability and antifreeze of concrete.
2. The problem of alpine hypoxia. As mentioned before, there are 960 kilometers of areas along the Qinghai-Tibet Railway with an altitude above 4,000 meters, accounting for 84% of the total length. The year-round temperature in many places is below -10°C. People often say, "When you reach the Kunlun Mountains, your breath is already dying; after crossing the five beams, you cry for father and call for mother; when you climb Fengshan Mountain, your three souls have returned to heaven." At an altitude of more than 4,000 meters, people often feel dizzy and nauseous, as if they are stepping on a ball of cotton, feeling weak and weak. People suffering from hypoxia will have headaches, brain swelling, chest tightness, shortness of breath, and sleeplessness at night, and can induce cerebral edema, pulmonary edema and other diseases.
The air is thin and the altitude is cold and lacks nutrients, so it is called the "forbidden zone of life". High cold and hypoxia seriously threaten builders during the construction of the Qinghai-Tibet Railway. Usually, people only pay attention to the cold and lack of oxygen inside the train after it is opened to traffic, but pay less attention to the millions of troops engaged in construction in the open air. However, the problem of high cold and hypoxia will not pose a great threat to the passengers in the train after it is opened to traffic. People only need to adopt some technologies and equipment on the train like an airplane; but for those who have been working hard for many years in the construction of the Qinghai-Tibet Railway, For builders, it is a deadly threat anytime and anywhere. In response to the problem of high cold and hypoxia, the Qinghai-Tibet Railway Construction Headquarters and experts have adopted the following solutions: 1? Adhere to the people-oriented principle and establish a third-level medical support institution to conduct regular physical examinations and timely treatment for builders. 2. Implement cascade adaptation to gradually enable builders to adapt to the climate and environment at different altitudes from low to high, and limit operating time and labor intensity. 3? Strengthen the construction of medical equipment and medical personnel. There are now more than 400 medical personnel at the construction site and more than 900 sets of medical equipment. Purchase 16 hyperbaric oxygen chambers (hyperbaric oxygen chambers simulate an atmospheric environment close to sea level through pressurization and oxygenation, and have comprehensive effects on treating various diseases caused by hypoxia and low pressure).
3. Environmental Protection Issues The Qinghai-Tibet Plateau is an important origin and differentiation center of mountain biological species in my country, Southeast Asia and even the entire world. It is listed as the highest priority area for global biodiversity protection by the World Wildlife Fund. The climate is cold, vegetation is sparse, the soil is shallow, and the ecological environment is extremely fragile. Once destroyed, it is extremely difficult to recover. These are the biggest ecological characteristics of the Qinghai-Tibet Plateau. The Qinghai-Tibet Railway passes through the hinterland of the Qinghai-Tibet Plateau, passing through the "Sanjiangyuan Nature Reserve" and the "Kekexili Nature Reserve". Therefore, environmental issues during construction are very important technical problems. After careful research and planning, experts have adopted the following environmental protection measures: 1. Ideological measures: Vigorously publicize the importance of environmental protection, require participating units to increase investment, and protect vegetation, frozen soil, wetlands, water sources and wild animals along the route in accordance with the law. It advocates "caring for the environment, caring for wild animals, and caring for every inch of green space as much as you care for your own life." 2. Technical measures: Use small colorful flags as signs to strictly divide the scope of mining ore construction and the driving routes of personnel and vehicles to prevent rolling and damage to vegetation in areas outside the construction scope. Dedicated personnel will collect domestic waste and bury it centrally. 3. Legal measures: The environmental protection supervision system is implemented across the entire line. The general headquarters entrusts a third party to monitor the entire environmental protection process. The Provincial Environmental Protection Bureau signs a target responsibility letter with the construction unit to clarify all aspects of environmental protection responsibilities. 4. Engineering measures: In order to protect the permafrost and plateau vegetation, advanced excavation technology is adopted in the continuous permafrost construction areas; measures to replace roads with bridges are set up to protect wild animals (foraging, migration, etc.) A green channel (a passage for wildlife passing the railway). It is worth mentioning that in late June 2002, in order to allow 9,000 Tibetan antelopes about to give birth to pass through the Qinghai-Tibet Line Wudaoliang construction site and go to the Zhuonel Lake area in Hoh Xil to give birth, the 12th and 14th Bureau of China Railway, which were responsible for the construction of this section, Construction workers from the bureau resolutely suspended construction in some areas, pulled out colorful flags, and evacuated personnel and machinery to ensure the smooth migration of Tibetan antelopes.