Stability Study And Engineering Treatment Analysis On Embankment Upon The Slope At Ando Section In The Permafrost Of Qinghai-Tibet Railway

It changes heat balance between natural ground layers and outside environment through filling railway embankment in Qinghai-Tibet plateau permafrost slope zone, which also leads to have changed geothermal field. And as a result of geothermal field dissymmetry and geometrical dissymmetry of slant slope embankment, the road deformation becomes dissymmetrical too. So We analyze and do research on present time and future the embankment stability to guide right design and construction, preventing the embankment's instability as a bad factor at such zone which will substantially threaten railway extended service. This paper shows you geothermal field changing characteristics, monthly average geothermal field changing characteristics, accumulation temperature changing characteristics, trend of permafrost table and characteristics of embankment settlement as well as horizontal displacement by analyzing geothermal field and deformation at Ando experimental section in Qinghai-Tibet railway. We predict geothermal changing characteristics in the future 50 years with numerical analysis, and set the calculated man-made table as the stratum boundary, based on intensity compensation theory and we use FLAC^3D software to evaluate embankment stability on different year in the future 50 years, and analyze embankment stability at different slope angles.We obtain conclusions as follows:1. Are-distribution of ground temperature field arises in permafrost area as a result of the construction of the Qinghai-Tibet railway. And geothermal field of embankment become dissymmetrical at ubac and solar slope due to the asymmetry of aspects and geometrical sizes, which also leads to a dissymmetry of embankment settlement;2. The horizontal and vertical displacement at solar slope side are all more than ubac slope side; The horizontal displacement and vertical settlement are relatively large at the first warm season after embankment filling, and the experimental section embankment comes to a stable thermal and dynamics balance after three freeze-thaw cycles;3. Prediction results from numerical simulation of geothermal field show that embankment permafrost will degenerate after future 20 years;4. The stability analysis of embankment slope show that the section now and in the future 40 years will be stable, and safety factor is increasing with permafrost gradual thaw; Under same conditions, the safety factor become larger as slope decreases.