Discrete Element Analysis And Experimental Study On Ground Improvement Of Airport Pavement In Seasonal Frozen Soil Region

The stability of the soil foundation is an important factor to ensure the later operation safety of the airport flight area facilities.However,the foundation in the frozen soil area is usually unstable due to freezing and thawing deformation,which makes the airport construction face many problems,especially the airport The characteristics of the wide flight area facilities and the large use load make the stability problem more prominent.As the frozen soil is more susceptible to thermal thawing subsidence under the influence of temperature,it is easy to cause the structure of the road to suffer from frost heave,tumbling,and road surface cracks and other diseases.In order to reduce the excessive deformation of the subgrade after its melt settlement,it is necessary to take appropriate anti-thaw settlement measures during the construction stage.In order to reduce the thawing of soil,it is necessary to study the thawing process of frozen soil,and it is necessary to study the characteristics and influence laws of its microstructure,so as to take appropriate control measures.In this project,with the help of laboratory experiments,the characteristics of nano-silica to improve the thawing settlement and thawing compression of frozen soil were studied,and its influence on the stability of foundations was studied based on numerical simulation.The improved melting and compression instrument was used to study the melting properties and melting compression of the nano-silica modified soil.It was explored that the nano-silica material can melt and melt frozen silty clay under different mesh numbers and different mixing ratios.The influence characteristics of the compression characteristics,the relationship between the melt settlement coefficient and melt compression coefficient,void ratio,pore water pressure and other parameters and the influence factors are analyzed.The SEM electron microscope was used to observe the change characteristics of the soil structure before and after the addition of nano-silica materials,and the mechanism of the thawing settlement of the silty clay samples was discussed.The test results show that the extremely strong water absorption of the nano-silica material can convert the free water adsorption in the pores of the soil particles into attached bound water,and reduce the free water moisture content of the soil,thereby making the soil optimal moisture content And the maximum dry density are increased;the melting coefficient and melting compressibility of the modified silty clay decrease with the mesh size and mixing ratio of nano-silica;the void ratio and pore water pressure of the sample are mixed with the nano-silica The ratio increases and decreases.When the mixing ratio is the same,the larger the number of particles with large meshes,the smaller the agglomerates of clay particles formed,which reduces the proportion of large pores between the soil skeletons and improves the void structure and strength of the soil.Based on the results of the discrete element simulation analysis,as the microscopic parameters of the sample decrease,the pore water pressure increases and dissipates quickly,and the effective stress between particles gradually increases;the stiffness of the particles has the greatest effect on the thawing coefficient of the frozen soil sample;The stiffness of the particles is proportional to the elastic modulus of the soil sample.As the stiffness of the particles decreases,the elastic modulus of the soil decreases and the compressibility becomes stronger.