THE ENGINEERING GEOLOGICAL CHARACTERISTICS OF THE SPECIAL SOIL ALONG THE RAILWAY LINE IN THE WESTERN REGION OF JILIN PROVINCE AND ITS GROUND TREATMENT

About 292km of the passenger and cargo railway line from Changchun to Baicheng in northeastern China passes through the western region of Jilin Province, and special soil exists in this area. There are liquefaction soil, soft soil, saline soil, seasonally frozen soil and other special soil in this region. According to the investigation of the railway line, the soft soil and the seasonally frozen soil exist along the whole line, the saline soil exists along the line from Songyuan to Baicheng, and the liquefaction soil exists in this area from Songhua to Daan. The seasonally frozen soil is very sensitive to the change of temperature, and the liquefaction soil is prone to the phenomenon of sand liquefaction under the actions of dynamic loads and earthquake. The soft soil has features of high water content, large void ratio, high compressibility and poor permeability. The saline soil has moisture, leaching, subsidence, erosion, swelling and other features. These special soil will decrease the strength of the roadbed, resulting in roadbed subsidence, uneven settlement and other hazards, and they impact on the railway's design and construction. To service the engineering practice, combined with the actual of the engineering, the distribution and engineering characteristics of these special soil were analysised on basis of the requirements of railway project, then appropriate measures for the treatment of the ground and approaches of strengthening the foundation were proposed.