? Qinghai-Tibet Railway is 1,142 kilometers long, divided into three sections to complete. 2002 built in Qinghai is the Qinghai-Tibet line is the most complex geological, technical difficulties of the largest Wang Kun (Kunlun Mountain) - Wang Tang (Tanggula Mountain) section, a total length of 410 kilometers. This section of the whole line *** have ten key projects, namely, six bridges (Sanqiaohe Bridge, Xueshuihe Yangtze River Source Bridge, Qingshuihe Bridge, Frozen Springs Bridge, Chumar River Bridge, Bara Caiqu Bridge); two tunnels (Wind Volcano Tunnel, Kunlun Mountain Tunnel); two roads (Wangkun Frozen Springs permafrost roadbed; Frozen Springs - Chumar River). (permafrost roadbed). These ten projects in the three major technical difficulties are also the most concentrated, prominent. Researchers and technicians through the Kunlun Mountain Tunnel, Wind Volcano Tunnel and other field research, has effectively solved the three major technical difficulties, as follows:
First, the problem of permafrost In the permafrost on the road, the roadbed with the changes in temperature and has instability. Due to the Tibetan Plateau, the temperature varies greatly from year to year, with a maximum temperature of 38℃ in summer and a minimum temperature of -40℃ in winter. Season of high temperature, permafrost thawing, the formation of hot melt lakes and ponds, dark rivers, roadbed slurry, sliding, roadbed formed rubbing road; temperature drop, roadbed frozen, and even perverse expansion, the formation of frozen up ball. Among the frozen soil, there are soil-containing ice layer, ice-saturated frozen soil, fissure ice, sandstone, mudstone, mud and sand interlayer. Temperature rise, resulting in thermal thaw expansion, especially in the open hole excavation, slope instability, landslide, base mud, tunnel excavation, the arch of the serious fall block, or even collapse, tunnel operation will be due to repeated freezing and thawing damage to the structure, affecting operational safety. After the opening of the railroad, there is bound to be a large amount of waste heat discharged from the car, which has an impact on the railroad roadbed. In order to solve the problem of permafrost, experts have adopted the following methods to ensure the stability and durability of the roadbed:?1?Adopting the schist ventilated roadbed, schist ventilated retaining roadway, paved with thermal insulation materials, and adopting the hot bar technology. (Ventilated roadbed and ventilated berms make air convection fast, so that the temperature of the roadbed is the same as the surrounding air temperature, and it is not easy to form a local hot zone, which is conducive to the stability of the roadbed).
2?In permafrost and unstable places using bridge instead of road (bridge repair on permafrost, no water below but unstable permafrost), such as Qingshui River Bridge.
3?Tunneling projects in the lining with a waterproof insulation layer.
4?Re-study and formulate concrete durability technical standards to improve the durability of concrete structures. In order to prevent thermal expansion and contraction of the piers appear tortoise, so that the concrete and permafrost "close contact", to take negative temperature maintenance measures, summer to take the digging of wells, cooling, cooling measures, so that the temperature is maintained at about 10 degrees Celsius, winter to take baking heat, add antifreeze, to the piers wrapped in quilts and other measures, to ensure that the durability of the concrete and frost resistance.
Two, cold and lack of oxygen
As mentioned earlier, the Qinghai-Tibet Railway along the altitude of 4,000 meters above sea level in the region of 960 kilometers, accounting for 84% of the total length of the line, the perennial temperature of many places in the -10 ℃ below. People often say, "to the kunlun mountains, the breath has been dying; over the five beams, crying father and mother; on the wind volcano, three souls have returned to heaven". At an altitude of more than 4,000 meters above sea level, people often feel dizzy, nausea, as if the feet stepped on a piece of cotton, weak. Oxygen deprivation will have a headache, chest tightness, shortness of breath, sleepless nights, will induce cerebral edema, pulmonary edema and other diseases. Thin air, cold and lack of nourishment, known as the "forbidden zone of life". Cold and lack of oxygen seriously threaten the builders in the construction of Qinghai-Tibet Railway. Usually, people only pay attention to the cold and lack of oxygen inside the train after the opening of the railroad, and care less about the millions of soldiers engaged in the construction in the open air. However, the problem of cold and lack of oxygen is not a big threat to the passengers in the train after the opening of the train, and people only need to take some technology and equipment on the train like airplanes to solve the problem; however, it is a fatal threat at any time and any place for the builders who have been fighting for years and years in the construction of Qinghai-Tibet Railway. In response to the problem of high cold and lack of oxygen, the headquarters of Qinghai-Tibet Railway construction and experts have taken the following measures:
1?Adhering to the principle of people-oriented, the establishment of three-tier medical security institutions, regular body checkups and timely treatment for the builders.
2?Implementing stepped adaptation, gradually adapting builders from low to high to the climate and environment at different altitudes, and limiting operating hours and labor intensity.
3?Strengthening medical equipment and medical personnel. Now the construction site of the medical staff of more than 400 people, equipped with more than 900 sets of medical equipment. Purchase of hyperbaric oxygen silo 16 (hyperbaric oxygen silo
through the pressurization, oxygenation approach, simulating an atmospheric environment similar to sea level, for the treatment of a variety of diseases due to hypoxia, low pressure caused by a comprehensive therapeutic effect).
Three, environmental protection issues
The Tibetan Plateau is an important origin and differentiation center of mountain biological species in China, Southeast Asia and even the whole world. It is listed by the World Wide Fund for Nature (WWF) as an area with the highest priority for global biodiversity protection. The cold climate, sparse vegetation, shallow soil, extremely fragile ecological environment, once destroyed, it is difficult to recover is the most important feature of the ecology of the Tibetan Plateau. The Qinghai-Tibet Railway passes through the hinterland of the Qinghai-Tibet Plateau, passing through the "Sanjiangyuan Nature Reserve" and the "Coco-Sily Nature Reserve". Therefore, the environmental problems in the construction are very important technical difficulties. After careful study and planning, the experts took the following environmental protection measures:
1?Ideological measures: vigorously publicize the importance of environmental protection, and require the participating units to increase investment and protect the vegetation, permafrost, wetlands, water sources and wild animals along the route according to law. Advocating "like caring for their own lives as caring for the environment, care for wildlife, care for every inch of green space".
2 Technical measures: small colored flags as a sign, strict division of the mining ore construction scope and personnel and vehicle routes, to prevent the construction of areas outside the scope of the vegetation caused by rolling and damage. The living garbage is collected by special personnel and buried centrally.
3?Legal measures: the entire line of the implementation of environmental protection supervision system, the General Command entrusted a third party to the entire line of environmental protection for the whole process of monitoring, the provincial environmental protection bureau and the construction unit signed a target responsibility, clear environmental responsibility in all aspects.
4?Engineering measures: in order to protect the tundra and plateau vegetation, in the successive years of permafrost construction section, the use of advanced excavation technology; set up a bridge instead of road measures for the protection of wildlife (foraging, migration, etc.) set up a green corridor (wildlife crossing the railroad).
It is worth mentioning that: in late June 2002, in order to let 9000 Tibetan antelopes on the verge of giving birth through the five beams construction site of the Qinghai-Tibet line, to the Coco-Colíli Zhuo Naier Lake area to give birth to their cubs, undertake the construction of this section of the Twelfth Bureau of the China Railway, the Fourteenth Bureau of the construction staff, resolutely suspend part of the section construction, pulling down the colorful flags, evacuation of personnel and machinery, to ensure the smooth migration of Tibetan antelopes.