| Lanzhou-Xinjiang high-speed railway spans Gansu,Qinghai and Xinjiang provinces,passing a variety of landforms along the way.As a result,the environment of Lanzhou-Xinjiang high-speed railway is complex and varied,and the engineering nature is complex.One section of the high-speed railway passing through the Qilian Mountains is a seasonal frozen area,and the frost heaving damage of railway roadbed appears there,affecting safe and smooth operation of train.With one severe frost heaving section of Lanzhou-Xinjiang high-speed railway,from Menyuan to Haomen,as research background,the frost-heaving characteristics and law of highspeed railway subgrade are analyzed and the main factors of frost-heaving of subgrade are determined,combined with the local hydrogeological and meteorological conditions.On this basis,the components of road-bed fillers,as well as the influence of filler components and other factors on the frost-heaving rate and frozen depth of fillers are studied,the prevention measures of subgrade frost heaving are put forward,which provides guidance for the protection and treatment of frost-heaving of railway subgrade.The main contents of research are as follows:(1)The frost damage of subgrade in the section of Lanzhou-Xinjiang high-speed railway,from Menyuan to Haomen,was investigated,and the frost damage characteristics and frostheaving law in this section were studied,combined with the research results of hydrogeological and climate condition there.On this basis,the factors and freezing damage law of LanzhouXinjiang railway are analyzed,which lays the foundation for the study of the frost-heaving of roadbed filler.(2)Picking up soil of the subgrade in the section with severe frost heaving,the routine geotechnical test of subgrade filling is carried out,including particle screening test,moisture content test,density test,compaction test and so on.The test analyzes the basic physical quantities of subgrade filling,such as particle size composition,natural moisture content,optimal moisture content,maximum dry density and so on.(3)The influence rule of subgrade filler characteristics on frost-heaving rate was studied,mainly including the influence of different particle gradation,moisture content as well as compactness of road-bed fillers on the frost-heaving rate of fillers,and the degree to which three factors influence the frost-heaving rate was compared,at the same time influence limit value of moisture content on frost-heaving rate was determined.(4)The influence law of the road-bed filler characteristics on the frozen depth is studied,mainly including the influence of different moisture content,compactness and temperature on the frozen depth,and the change of the extent to which three factors influence the frozen depth is analyzed.(5)Combined with on-site research and experimental research,the change law of the frostheaving rate and frozen depth of the road-bed fillers under these factors were summarized,and reasonable and effective prevention and control measures are put forward for the frost-heaving problem of subgrade according to local conditions. |
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