Characteristics of subgrade's temperature, moisture and frost heave deformation in Haomen, passenger railway line from Lanzhou to Xinjiang

The safe operation in high-speed railway in cold regions are effected by feeble frost heave of subgrade' carrier with coarse particle and fine particle. Study the characteristics of temperature, moisture and frost heave deformation in different deep of subgrade, based on the 4 fracture surface where installing thermometers, moisture meter and frost heave instrument in different deep of subgrade in Haomen belong to the second line of Lanzhou-Xinjiang railway. The results show that the more sensitive of temperature the more close to the earth's surface, and there is no minus temperature under surface 3 m.The maximum value of frost-heave is 2.1 cm above 2.7 m layer. The deep of 0-0.5 m during the cold season the lowest temperature varies from -10.3[degrees]C to -15.6[degrees]C. During warm and initial freezing period, the water content is relatively higher can be reach to 15%, frost heaving ratio is about 4.86 mm[middot]m-1, so grading macadam under the condition of high moisture content and low temperature can effectively weaken the frost heave. The maximum rate of frost heave (14.34 mm[middot]m-1) occurs between 0.5-1.5 m, which layer carrier is ordinary AB group. The lowest temperature varies from -7.2[degrees]C to -12.4[degrees]C in cold season. During warm and initial freezing period, the water content is between 10% and 15%. Between the deep of 1.5-2.7 m layer the frost heaving ratio is about 1.94 mm[middot]m-1, the lowest temperature varies from -3.2[degrees]C to 0.4[degrees]C in cold season. During warm and initial freezing period, the water content is between 12.5% and 15%. The higher content of fine particle the more higher of the frost heaving ratio. Therefore the content of fine particles should be control under 15%.