Study Of Frozen Soil Environment Relating To Qinghai-Tibet Railway Embankment

Frozen soil environment is the important component of plateau ecological environment, the frozen soil environment has been very fragile in Qinghai-Tibet plateau permafrost areas. Embankment construction on permafrost will substantially deteriorate frozen soil and ecological environment, interfere the balance of the frozen soil ecological environment along Qinghai-Tibet railway, make project district and relevant frozen soil environment of area and earth's surface vegetation changed, etc. Those changes will make the originally fragile plateau frozen soil and ecological environment suffer artificial destruction. At the same time the change of the frozen soil environment exerted an unfavorable influence on embankment itself too. Under compare specific frozen soil environment in Qinghai-Tibet plateau, for ensuring the stability of embankment and preventing the thermal perturbation impacting on frozen soil environment, it is important to predicting the change of the frozen soil environment, on the premise of protecting frozen soil environment, rational transformation and utilizing the frozen soil environment to have certain directive significance.By explaining the concept of frozen soil environmental and analysing the influence factors of the frozen soil environment in the paper, simply analysing the mechanism of embankment influence the frozen soil environment. Seeing that the thermal regime of frozen soil is research base of the frozen soil environment, using the 2-D finite element analysis to simulate the change of thermal regime under embankment, and according to the change analysing and appraising frozen soil environment.We can draw the following conclusions by synthesizing the above:(1) With the change of thermal regime under embankment, appearing unfavorable condition of frozen soil environment protection, such as making thawed depth deepened, the temperature of permafrost rises, etc.(2) The thermal perturbation bring about many changes in frozen soil environment, for example the permafrost table, thickness of frozen soil and accelerating the frozen soil to degrade, etc.(3) Setting about aspects of unfavorable frozen soil environment protection, analysing the situation that may highly cause the permafrost table to drop withdifferent mean annual air temperature and height of embankment, when mean annual air temperature are-5.2°C % -4.5"Cand-3.5°C, respectively, the minimum embankment heights obtained from the analysis are 2.9 m , 3.9m , 4.5 m. (4) According to the destruction characteristic of Qinghai-Tibet highway, the change of frozen soil environment bring about influence along Qinghai-Tibet railway, for example, thaw settlement, frost heaving, thaw settlement is one of important problem among them.