| Seasonal frozen soil is an extremely sensitive and unstable soil.Its physical properties change dynamically with the change of climate and temperature and the development of freezing and thawing process.The seasonal freezing and thawing of the roadbed in seasonal frozen soil area is obvious,subject to seasonality.The effects of frost heaving and melting and sinking lead to a series of freeze-thaw disasters such as expansion,cracking and tumbling.The durability,practicality and safety of the road are seriously affected.In recent years,with the development of the western region and the steady construction of the “13th Five-Year Plan” infrastructure,the construction of roads and railways in the seasonal frozen areas of western Sichuan will accelerate,while the problem of frost heaving and subsidence of the subgrade in seasonal frozen soil areas is very prominent.And related research results are few.Therefore,it is necessary to study the treatment of frost heaving and sinking of seasonal frozen soil in the western Sichuan Plateau,which can provide reference for the treatment of road frost heaving and sinking.In this paper,the Kangding-Xinduqiao National Highway in the seasonal frozen soil area of the western Sichuan Plateau was studied.The test system of the roadbed soil freeze-thaw cycle effect was developed.The freeze-thaw cycle model test was carried out,and the model test of the subgrade water-hydraulic coupling model was established.,verifying the reliability of the model test.According to the analysis results,the effectiveness of seasonal frozen soil roadbed treatment measures is proved.The main research contents and results are as follows:(1)Developed a test system for the treatment of roadbed freeze-thaw cycles.In order to simulate the freeze-thaw cycle effect of the subgrade in the seasonal frozen soil area of the western Sichuan Plateau,the temperature,humidity and groundwater conditions were considered.The programmable test chamber,temperature and humidity collection device,stress and strain collection device,thermal insulation device and water and drainage board were designed.Three-dimensional geotextile system,automatic heating device,etc.,can collect and record the temperature and volume moisture content and roadbed deformation in the roadbed model in real time.(2)Several freeze-thaw cycles were tested on the subgrade model.Through the results of multiple freeze-thaw cycles test,the water content,temperature and roadbed deformation law of the model body in each cycle freeze-thaw phase were studied and analyzed,and the freeze-thaw cycle effect of the roadbed in the seasonal frozen soil area in western Sichuan was studied.The comparison verified the effectiveness of the proposed measures for thefrost heaving and sanitization of seasonal frozen soil roadbed.(3)Numerical simulation analysis of the model test was carried out.Based on the existing hydrothermal coupling equations and models,the indoor model test is numerically simulated.The comparison between the simulation results and the model test results shows that the two laws have strong similarities,which proves the accuracy of the model test results.Sexuality,verified the seasonal frozen soil roadbed,through the laying of composite water-proof board and three-dimensional geotextile to inhibit the groundwater migration to the interior of the roadbed and the laying of thermal insulation board to hinder the heat exchange between the roadbed and the environment.The feasibility of the sink and the effect of the treatment are more obvious.In this paper,through the development of the roadbed freeze-thaw cycle effect disaster control test system,the model of the frozen-thaw cycle effect of the subgrade in the seasonal frozen soil area was tested and numerically simulated by modeling.The conclusion of the study is on the seasonal frozen soil area of the western Sichuan Plateau.The treatment of frost heaving and subsidence of subgrade has certain reference significance. |
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