Experimental And Simulation Study On Deformation Mechanism Of Swelling Soil Slope In Seasonal Frost Zone

In recent years,the influence of the freeze-thaw environment in the monsoon zone on engineering construction and the problem of expansive soil slopes have attracted wide attention at home and abroad.With the increase of engineering construction in the monsoon freeze zone,the disaster problems of the monsoon freeze zone slopes have emerged continuously,and the deformation mechanism of the slopes under the freeze-thaw cycle in the monsoon freeze zone has become one of the urgent topics for research.In this paper,the research work is carried out by indoor model tests and numerical simulations on the slopes of expansive soils.This paper combines indoor model tests and numerical simulations to analyze the physical properties of the slopes of expansive soils during freeze-thaw cycles,to study the slope response characteristics of the slopes of expansive soils under freeze-thaw cycles,and to consider the effects of different initial water contents and different slope ratios on the deformation mechanism of the slopes of expansive soils under freeze-thaw cycles.The influence factors and mechanism of slope stability of expansive soil slopes are of guiding significance to the construction of expansive soil slopes.The effectiveness of the numerical simulation method is verified by using COMSOL software to analyze the multi-field coupled simulation of the slope under the freeze-thaw cycle and comparing with the model test results.Through the comprehensive analysis of deformation mechanism and stability of swelling soil slope in the monsoon freezing area,it provides the basis for the engineering design of road rift slope in the monsoon freezing area.The main research results are as follows.(1)Freeze-thaw cycles,as a strong weathering effect,change the physical and mechanical properties of the soil body of the expansive soil slope;in the process of multiple freeze-thaw cycles,all monitoring data of the expansive soil slope show periodic changes,and the first freeze-thaw has the greatest influence on the soil body of the slope;in addition,during the freeze-thaw process,the slope shows the phenomenon of one-way freezing and two-way melting,and the overall melting rate is greater than the freezing rate;with the increase of the number of freeze-thaw cycles,the arrangement between the soil skeleton and soil particles becomes more and more stable,the amount of change of each index gradually decreases and becomes stable,and the state of the soil body develops from an unstable state to a dynamic stable state.(2)The initial moisture content of the slope body affects the stability of the slope by influencing the water migration inside the slope body.The lower the initial moisture content,the more obvious the slope surface fracture development and the deeper the lateral fracture development,while the higher the initial moisture content of the slope,the longer the time required to reach freezing stability,the greater the change in soil pressure,and the greater the freezing and swelling rate;in addition,there is "freezing and swelling and thawing" or "freezing and swelling and thawing" in the soil of slopes with different initial moisture content.In addition,there are two phenomena of "freeze-shrink-thaw" or "freeze-shrink-thaw" in the slopes with different initial water content,but the slopes as a whole are developing towards the hollow surface;with the increase of the number of freeze-thaw cycles,the degree of slope fragmentation of slopes with different initial water content gradually increases.(3)In the model tests with different slope ratios,the slope surface fracture development is more obvious for slopes with larger slopes;with the freeze-thaw cycles,the fracture width and fracture depth are also proportional to the slope ratio;the slope slope affects the internal temperature transfer rate of the slope,the steeper the slope,the greater the environmental influence at the same buried position under the slope surface,the smaller the stress per unit area that the soil body is subjected to,the corresponding expansion rate is larger,and the displacement change is larger;the slope slope surface fracture development is more obvious for slopes with different initial water content.In the test process of this paper,the slopes of swelling soil with different slope ratios show the phenomenon of "freeze-shrinkage and thawing",and with the increase of the number of freeze-thawing,the suitable slope ratio design is beneficial to the stability of the slopes of swelling soil.(4)Through the analysis of the simulation results,it is obvious that the top of the slope is most influenced by the ambient temperature,and the freeze-thaw process shows the phenomenon of one-way freezing and two-way thawing;in addition,due to the effect of water redistribution in the freeze-thaw process,the distribution of water content inside the slope body is obviously different from the initial state after freeze-thaw,and the change law of slope body temperature also reflects the change characteristics of water content inside the slope body accordingly.The research results are of great significance to further investigate the stability and destabilization mechanism of swelling soil slopes in the monsoon freezing zone,and can provide a better theoretical basis and scientific basis for the study of the stability of swelling soil slopes in the monsoon freezing zone.