Numerical Simulation For Stability Of Subgrade On Seasonal Frozen Area

The highway reconstruction project of the State Road 213 which from the Lang Musi to Chuan Zhusi passes through China's largest plateau wetland—Ruoergai wetland. The problem, such as frost heave, thaw settlement appears frequently in seasonal frozen soil subgrade on the plateau, which has brought enormous inconvenient to the driving. The importance of this article is the study of the stability of seasonal frozen subgrade, which has mainly Reference value for highway design in northwestern Sichuan in futureFor especial geographical and climatic conditions, rising soil of the road in seasonal frozen soil region is more severe and complicated than that in other region. The disease is exterior reflection of asymmetrical settlement and mechanical performance reducing of road material. In the paper, the displacement and stress of pavement structure under different subgrade thawing depth are analyzed by ABAQUS software. Comparing analyzed results, a conclusion will be drew that rising soil is caused by a series of influence factor at the same time; the countermeasures against road structure disease are designed by contraposing reviewed road disease traits in permafrost region.The author has carried on the seepage simulation in view of the moisture content migration to the subgrade. In order to enable the subgrade to have the enough intensity, the overall stability and the water stability, the subgrade height should satisfy the requirements of the smallest the critical altitude as far as possible; it also needs to meet the requirements that subgrade should be in situation of dry or little wet condition all the time. In the environment of seasonal frozen soil on the plateau, the height of the subgrade is mainly decided by the height of capillary water ascending, the ground water's position together. Generally taking account of all the factor, the project that subgrade height take 1.5m depth are proposed, the method laying the water percolation insulating layer in the lower part of subgrade are adopted if necessary. Based on the water translocation mechanics of predecessors study in the seasonal frozen soil and the setting ways of the subgrade insulating layer and thickness, according to climate and soil texture condition in northwestern Sichuan district, the setting location of the subgrade insulating layer in the seasonal frozen soil ground in this area is analyzed and studied. The seasonal frozen soil subgrade is analyzed by using ABAQUS finite element program. Study shows that the optimal position of the insulating layer setting is about 1.0m under the top surface of subgrade in northwestern Sichuan district. On the one hand, it satisfies the requirements of the subgrade's intensity and overall stability; on the other hand, it meets the requirements that subgrade is in situation of dry or little wet condition.