Numerical Simulation Of The Influence And Variation Of Freeze-thaw Cycles On Seismic Stability Of Slopes In Cold Regions

There are a lot of overlaps between seismic zones and cold regions in China,so the seismic stability analysis of slopes in cold regions is particularly important.Due to the existence of freeze-thaw cycles,the seismic analysis of slopes in cold regions is more complicated than that of ordinary slopes.In order to intuitively reflect the influence of freeze-thaw cycles on the seismic stability of slopes,based on the finite element analysis software,this paper takes soil slopes with different slopes and different water contents as the research object,and uses the method of associating the mechanical parameters of soil with the number of freeze-thaw cycles to study the variation law of seismic stability of slopes under freeze-thaw cycles.The main work contents are as follows :(1)According to the relevant literature,it is determined that the shear strength of the slope is affected by freezing and thawing.The shear strength of the soil is greatly affected by freezing and thawing.The cohesion and internal friction angle will decrease with the increase of freezing and thawing times and soil moisture content.When the number of freeze-thaw cycles reaches a certain number,the cohesion and internal friction angle tend to be stable.The empirical formula of the shear strength of the soil with the number of freeze-thaw cycles and the water content of the soil is in the form of a binary power function.According to Fourier ’s law and Darcy ’s law,the temperature control equation and water control equation of frozen soil are derived.(2)According to the average monthly temperature of a certain year in Qinghai,the temperature boundary function is determined,and the temperature field of cold slope under different slope and different water content is analyzed by finite element analysis software.According to the results,the temperature difference of the same slope in different months is different,and the surface temperature difference between cold season and warm season is larger.The surface of the slope is most affected by the temperature change,and the influence of the temperature change on the soil inside the slope gradually decreases with the increase of the depth.There are obvious differences in temperature at different positions of the same slope in the same month.When the slope is completely frozen,the pore ice content and distribution vary with slope and water content.At the same depth,the change rate of pore ice under different slopes is different.The rate and depth of pore ice change under different water content are also different.The higher the water content,the deeper the freezing depth when the slope is completely frozen.(3)According to the specification,the pseudo-static method is used to calculate the seismic stability of the slope.The finite element analysis software is used to simulate the stability of the cold slope with different slopes and different water contents under the action of seismic load in the non-freeze-thaw state and the freeze-thaw state.According to the simulation results,under the action of freeze-thaw cycles,the seismic safety factors of slopes with different slopes and different water contents decrease with the increase of freeze-thaw cycles.When the number of freeze-thaw cycles is 15,the number of freeze-thaw cycles begins to stabilize after 9 times.Under the action of seismic load,when the slope is frozen,the safety factor will increase,and it will decrease after melting.From the simulation results,the influence of slope change on the seismic stability of cold slope is greater than that of water content change.In this paper,the influence of freeze-thaw cycle on the seismic resistance of slopes in cold regions is studied by theoretical analysis and finite element simulation,which can provide theoretical basis for the subject or project related to seismic analysis of slopes in cold regions.