| As a special type of subgrade soil,the two-layered soil subgrade with upper dry crust has been widely concerned by many scholars.With the development of economy,the highway vehicle flowrate,vehicle weight,driving speed have increased gradually,the impact of these factors on the stability of subgrade can’t be ignored,so it is more and more important to study the dynamic stability influence factors of the two-layered soil subgrade during the operation period.The soft clay and dry crust samples after the dynamic three axial test were amplified different times by scanning electron microscope text,and then to make the qualitative analysis of the soil’s microstructure under dynamic load by the 3D reconstruction through the MATLAB.The directional frequency,shape of pore ratio and pore classification of soil in different dynamic stress amplitude,confining pressure,moisture content and load cycles frequency was calculated by IPP.Based on the fractal theory,the Changing tendency of the porosity and fractal dimension under different conditions were calculated by MATLAB.Furthermore,the influence of different factors on the stability of soft clay and dry crust is revealed from the point of view of meso-structure.Based on the study of meso-structure and analytic hierarchy process.On basis of laboratory model test,dynamic triaxial test and scanning electron microscope test,the hierarchical structure model was built by virtue of three mark of AHP combining experimental data and expert scoring,in which the criterion layers were vehicle load parameters,soil layer distribution feature and mechanical parameters,soil physical indicators and cyclic action parameters,and the Subjective weight order of multiple factors is obtained after the judgment matrix is calculated by MATLAB procedure.In order to solve the problem that the analytic hierarchy process has a certain degree of human disturbance.Objective weight order of multiple factors was calculated by Gini coefficient method in this paper.The subjective and objective weights are optimized to get the final combination weights,that is,the order from large to small are load cycles times,dry crust thickness,load cycles frequency,vehicle weight,dry crust hardness,soft clay moisture content,driving speed and dry crust moisture content.The research results can eliminate the interference of human factors,it can be more scientific,and have important engineering significance. |
