Research On The Slope Instability Mechanism On Freezing And Thawing Of K560+300～k561+000Section Of Tongjiang-Sanya Highway

In recent years, the three-year battle with the Heilongjiang Provincial Highway Construction perfect end, which greatly improved travel conditions, stimulating local economic development. However, the rapid development of highway construction, as well as the quality of the project requires in-depth research. Due to our province belong to the frozen soil areas in the high-latitude, the soil in slope of the highway freeze in winter and thaw in spring. The soil texture cut slope of highway often has phenomenon of freezing and thawing instability, which seriously affect the safety of the road operator and road region landscape.This research area lies K560+300-K561+000section of Tongjiang-Sanya highway. It is located in the central southern Heilongjiang Province, which belong to a cold temperate monsoon climate zone. The winter is longer, and the spring and autumn are shorter. Winter average temperature is-14.7℃, and summer average temperature is18.0℃. Ground stability freeze datein late November, and stable thaw in mid-April of the following year, and the maximum freeze depth of2.2m and seasonal frost depth1.8to2.2m.The average annual rainfall is between300-700mm.By sliding of slope freeze-thaw effect significantly, the major form of sliding is commonly within slope100cm depth of shallow sliding, and more focused on between40-90cm. In the spring melt period, the main influence factors of the slope instability of test sections has melting depth, slope gradient and water content, and their changes directly controls the change of the slope stability of the test sections.Combining with the field monitoring, laboratory test and numerical simulation analysis, this thesis study failure form, failure mechanism and stability analysis of instability freezing and thawing on soil cutting slope in the test sections during the spring melt period. Through field soil slope land moderate and water content monitoring, soil slope can be drawn from the rule of seasonal freezing and melting of permafrost, and in the process of its water content changes. Through the laboratory test study physical and mechanical parameters of soil slope on the spring melt period. On the basis of data of field monitoring and laboratory test, using the slice method which is put forward by Feilunniusi calculate t the slope safety factor along with water content change and change on the test sections in the freeze-thaw period. At the same time, using Plaxis calculate soil slope safety coefficient variation law under the condition of different melting depth and gradient of slope.