Research On The Chang Rule Of Temperature Moisture And Frost Of Silty Soil Subgradein In Seasonally Frozen Region

Silt soil is the product that made by the different degrees of weathering, the particles is between fine-sand soil and powder soil, The particles mainly in the sand and silt, while the cohesive particles content is less viscous. Silt soil's natural moisture content is low, when the particles is smaller the capillarity is more developed. The moisture accumulation phenomenon of migration is more significant in silt soil subgrade in the freezing process in seasonal frost region, the moisture in the subgrade which filled with Silt soil have a large range and have a relationship with the changing of humidity of the subgrade in a negative temperature conditions will aggravate the subgrade freezing. Subgrade frost damage in northern China has been particularly troubled by the severe cold area road construction season is a difficult problem.In order to understand the changing of soil subgrade's temperature and moisture in seasonal frost region and the subgrade soil strength after various times of the freeze-thaw cycles variation, the paper selected two representative samples in the Nen River Valley, Using self-developed monitoring facility consummates the subgrade moisture and temperature data; Based on this test obtained with powder room heaving sand at different moisture content and compaction rate under the conditions of frost heave; According to test results and the subgrade frost heave mathematical model to calculate the amount of subgrade, the calculated frost heave compared with the measured results of the reliability of the mathematical model of frost heave test; To further understand the silt in the intensity of freezing and thawing cycles were studied, in the optimum water content and dry density of the different conditions with different indoor freeze-thaw cycles CBR test. All the results show that:in the freezing process of the subgrade and under the effect of temperature, more to the accumulation of the phenomenon of migration of the upper subgrade more significant; In different depths of the subgrade, the temperature and water are different, freezing unit thickness (0.2m) of soil is different in the time required; Heaving silt subgrade increased with the change of moisture content and compaction, the change of moisture and compaction are the two main factors of subgrade frost heave; CBR is decreased after thawing cycles. This study area can be provided theoretical support for similar silt subgrade construction, design, and disease control frost heave in seasonally frozen region.