Study On Frost Heaving Force And Deformation Of Pile-Slab Retaining Wall

Under the guidance of the national “Belt and Road”development strategy,a large number of transport infrastructure,such as roads and railways,began to be built in the western region.The southwest region is located in the seasonal frozen soil region,and the structures in the frozen region are often deformed or cracked due to the frost heaving,which poses a great threat to the safety construction and normal operation of the project.In order to further study the effect of Frost heave on structures and provide design and prevention measures for practical projects,this paper takes the foundation pit of unsaturated soil engineering in seasonal frozen soil area of West River as the research object,through the combination of experimental measurement,theoretical derivation and numerical simulation,the space-time Variation of temperature field,frost heaving deformation,Horizontal Frost heaving force distribution and calculation method of foundation pit soil and pile-plate retaining wall in freezing period are studied:(1)The density,moisture content,grain size distribution and frost heaving rate of the specimens were determined by the experimental study on the frost heaving characteristics of unsaturated mixed soils in the seasonal frozen soil region of Kawanishi.The frozen expansion of soil is bound to have an impact on the stability and durability of supporting structure.(2)Based on the thermo-mechanical coupling theory of frozen soil,the thermomechanical coupling mathematical model of seasonal frozen soil foundation pit is established.According to the simulation analysis,because the thermal conductivity of the retaining wall is large and the heat transfer is good,the soil near the pile plate,that is,the negative temperature two-way transfer soil is greatly affected by the ambient temperature,and the freezing depth reaches 3.5 m,the variation range of soil temperature is more obvious and the duration of negative temperature is longer than that of negative temperature.(3)Through the secondary development of the thermal expansion subprogram of the finite element software,near the back of the wall and surface soil.According to the Orthogonality of frost heaving deformation,the volume expansion deformation mainly occurs in the direction of heat flow after freezing.At the top of the pile wall,the soil is subjected to both horizontal and vertical negative temperature,so the frost heaving deformation develops in the direction perpendicular to the temperature gradient and has a great influence on the horizontal displacement of the pile wall.However,the remote soil is only subjected to the vertical heat transfer of atmospheric ambient temperature,and the frost heaving deformation mainly occurs in the vertical direction.(4)According to the characteristics of short duration of negative temperature and shallow freezing depth in seasonal frozen area,it is concluded that the soil at the top of pile wall is affected by negative temperature in both directions,and the maximum value of Horizontal Frost Heave Force should appear at the top of pile wall,the effect of Frost Heave is weakened,the active earth pressure is increased,and the stress on the back of the wall shows the trend of decreasing first and then increasing.