Research On Freeze-thaw Slumping Mechanism Of Harbin-dalian High-speed Railway Slope In Seasonally Frozen Soil Region

The soils from seasonal frozen region, freeze and expand under low temperature in winter, thaw and settle under high temperature in spring. The shear strength of the soil in freez-thaw transition zone reduces because of freeze-thaw repeatedly. That leads to freeze-thaw slupmping of highway and railway subgrade, which brings about safety accidents and huge economic loss. This article, which is based on Harbin-Dalian High-speed Railway project, analyzes the meachincal properties of the soil in freez-thaw transition zone and induces freeze-thaw slupmping mechanism of subgrade slope to reduce the loss of freeze-thaw slupmping accidents. Through this way, theoretical guidances could be provided to pratical engineering. Several aspects are mainly reseached in this dissertation.(1)Theoretical analysis has put on parameters of shear strength from triaxial compression test (UU) on undisturbed soils from the D3K691+750~D3K691+850stability-testing of Harbin-Dalian High-speed Railway Dedicated Line. It deduces that the soil’s cohension and internal friction angle are affected by moisture content and freeze-thaw cycle index. Import the test data to Matlab and deduce the relation expression of the cohension and the internal friction angle with moisture content and freeze-thaw cycle index. Definit damage coefficient and deduce the relation expression of the damage coefficient of cohendion and internal friction angle with moisture content and freeze-thaw cycle index to provide theoretical guidances for the slope’s numerical calculation.(2) Build the seasonal frozen high-speed railway slope’s compute model in ABAQUS, theoritical and numberical analysis is carried on. Compute the temperature field of the slope in winter and spring. The maximum frozen depth of the slope is1.7meters. The melting depth increases gradually and the freezing and thawing interface comes down gradually during the melting phase. The frozen soil melts totally in late may.(3)Bring in the attenuation formulas of shear strength parameters to calculate the safety factor of slope, which decreases gradually during the melting phase. Analysis the slope’s plastic strain, displacement, stress field, etc comprehensively to determine the sliding surface. Compared it with the temperature field to conclude that frozen-thawed interface is the risk of the slope sliding.(4) Analyze the effect of moisture content, freeze-thaw cycle index and grade of slope to the slope’s stability. It is concluded that the stability of the slope decreases with the increase of the moisture content, freeze-thaw cycle index and grade of slope.