Reason Analysis and Treatment Measures of Subgrade Defects at Bridgehead in Permafrost Regions along Qinghai-Tibet Railway

Focusing on the subgrade defects in the permafrost region since the Qinghai-Tibet Railway had been put into operation,the thesis analyzed and researched the classification,the reasons and the main control factors about these subgrade defects. And then,after analyzing the main influence factors on these subgrade defects which occurred at the bridgehead in the permafrost region along Qinghai-Tibet Railway,the thesis put forward the engineering measures for the treatment of these defects. In addition,a forecast for the variation tendency of thermal stability of subgrade engineering in the permafrost regions was carried out.