| Qinghai-Tibet railway is a plateau railway with the highest altitude and longest circuit in the world, which is an exploratory project without practice both at home and abroad, and its engineering construction environment is very harsh and special. In such special environment, only by settling the frozen soil problem in the plateau well can it guarantee the stability and security of the road bed during the railway well running. The construction of the road bed project has changed the balanced state of heat of bottom permafrost of road bed in the permafrost district of Qinghai-Tibet railway, thus making the whole ground temperature field, upper limit of the frozen soil and thickness of frozen soil activity layer all changed, and making every part of road bed produce uneven subsiding deformation. The temperature sensitiveness body characteristic of the frozen soil determines that the heat state of the railway road bed of permafrost district is a key factor of the road bed stability. So with An duo frozen soil road bed test section as research entity, relying mainly on surveying data, and numerical simulation calculation as complement, I study the temperature field and deformation state of the embankment. Main contents: 1. At first this paper describes the outline of Qinghai-Tibet railway project, and introduced the conception, distribution, characteristic of this special frozen soil. It analyzed geological problems of the project such as melted and sinks , frost heaving and harmfully frozen soil geological phenomenon and so on; Scientific research overview of cryopedology. And then it explain the research background and meaning of this paper. 2. It discussed the special frozen soil environment of Qinghai-Tibet railway, and analyzed the characters of construction method of An duo railway bed and overview of test section. Qinghai-Tibet Plateau permafrost's characters of distribution was limited not only by latitude area but also high area, at the same time it was influenced strongly by regional factors such as direction of slope, vegetation, snow overlaying, geological structure and ground water etc. This determined that the geographical factor of regional geology is an origin of forming island shape frozen soil, and the geological structure condition was one of the most powerfullest factors that influenced the plateau frozen soil characters. 3. On the basis of the practice monitoring data of Qinghai-Tibet railway permafrost district An duo embankment test section during the end of 2003s till the end of 2004, with a series of systematic analyses we obtained the law that temperature field varise with the time, depth change. Have drawn : Having gone through one back to freezing, compared with natural upper limit, there is a lifting in various degree in the artificial upper limit under the shoulder of road bed, partly enter the basic body of road bed, proving the effective protection stone road bed to frozen soil environment; Ground temperature and temperature has the same fluctuate characters in different depth, and ground temperature presents sine fluctuate curve; But with the depth rising, the fluctuating range of ground temperature reduc gradually, and present lag phenomenon; The cold reserves of the ground rose, which proved that the building of the embankment does worsen the living environment of permafrost too, instead played a role in protecting the permafrost. 4. Having analyzed the horizon and vertical deformation law of road bed, we obtained that under the function of embankment self-esteem stress, the compression deformation of basic body embankment takes place mainly in the first warming season after embankment construction; The bad gradation packing of road bed makes the space among the soil and particle relatively big, reduce the inflow of heat in warm season with the function of hat shielding, improve spread into cold quantity in cold season, to play a role in protecting permafrost, which is very suitable. The asymmetric of embankment and ground temperature field from the center of the embankment and different steps of the soil body melt depth of different embankment slope, were the basic reason of large subsiding amount of sunny slope and little subsiding amount of moon slope of the embankment. 5.Utilizing ANSYS finite element software, combining indoor test data, test section's geology materials of drilling and road bed section size I have set up the calculate models of finite element, and simulated the change law of Temperature field...
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