|Alternative Title||Study on State of Subgrade Engineering in Permafrost Region during Operation Period of Qinghai-Tibet Railway
|Place of Conferral||兰州
|Other Abstract||The dissertation, by employing the methods of field survey and observation, laboratory test, theoretical analysis and calculation, will make an analysis of the surrounding temperature and permafrost character which affect state of subgrade engineering of Qinghai-Tibet Railway (QTR), explore the changing mechanism of the state of subgrade engineering in operation period through field investigation and monitoring of the state of subgrade engineering in permafrost region during operation period, examine the changing features of the state of subgrade engineering under different geological environment and in different stages of construction and operation and research on engineering countermeasure which can assure that state of subgrade engineering conform to OTR’s operation condition and make an evaluation about long-term effect. After the research on the state of subgrade engineering in the permafrost area during operation period of QTR, the major innovative conclusions will be presented as follows:
(1)The state of subgrade engineering includes the explicit mechanical state and implicit thermal state of the subgrade and outside hydrothermal environmental changes, and it is put forward that the thermal state of the subgrade is the dominant and controling factor resulting in the subgrade deformation and instability.
(2)The internal reason for changing mechanism of subgrade engineering state lies in cohesive strength of fill and compressibility of base soils, and the fundamental cause was asymmetric configuration of ground temperature field in fill and base soils. The late period of evolvement is related to the effect of outside hydrothermal environmental.
(3)Engineering measurements of controlling asymmetric configuration of ground temperature field are the key method to preventing and improving the diseased subgrade engineering, with auxiliary protection of hydrothermal environment of surrounding.
(4)During QTR operation period, when it comes to the improvement of diseased subgrade engineering state in permafrost region, it is suggested that the sorts of the thermosyphon combined with crushed rock slope protection structure, the crushed rock berm reinforcement structure, and the crushed rock slope protection reinforcement structure will be adopted, according to the differences of regional permafrost, climate conditions and original subgrade structure.|
李永强. 青藏铁路运营期多年冻土区路基工程状态研究[D]. 兰州. 兰州大学,2008.
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