A Model Test Study On Stability Of Subgrade In Seasonal Frozen Soil Area

Based on research of predecessor and model experiment, the stability of seasonal frozen subgrade is approached. The highway reconstruction project of the State Road 213, which from the Lang Musi to Chuan Zhusi is taken as engineer background.Combining the characteristic of the seasonal frozen subgrade ,through analyzing altitude and position of the insulating layer of seasonal frozen subgrade by big and small proportion model experiment ,and simulated subsidence distortion conditions of the subgrade which was experienced several natural freezing and thawing cycles under the stress of wheel load. The results of the test show that the whole intensity and comprehensive stability of subgrade made a good progress because the capillary water can't rise by using the insulating layer. In the prior condition of taking insulating layer thickness as 0.2m, choosing insulating layer 0.5m, 0.8m, below the pavement, the stability of seasonal frozen soil subgrade is analyzed. The results of the test also show that the optimal position of the insulating layer is 1.0m～1.5m .By tested and researched lots of predecessor's materials and achievements, writer made a detailed exposition for the reason and preventing and controlling measures of the heave and the frost heave of the subgrade. He made a qualitative analysis for origin of the capillarity and proposed one viewpoint that temperature, soil texture, mineral ingredient content, water factors and so on affect together the subgrade heave. He analyzed the source of water in the subgrade, and proposed the viewpoint of the affect of subgrade stability by the different sources of water like the water seeping from road surface, the water entering slope of subgrade, the graoude capillary water and so on.The research results can provide reference for design and construction of subgrade in seasonal frozen soil region.