Experimental Study On Deformation Characteristics And Long Term Stability Of Double Layered Soil

With the rapid development of expressway in China,more and more highways and high-speed railway constructions base on the soft soil subgrade in the upper crust,it is the problem of deformation stability in the long-term effect of Subgrade under traffic loads that has increasingly attracted much attention in the field of engineering,which has always been the academic focus of study.In this paper,the above crust soft soil subgrade as the research object,the deformation characteristics of double layer subgrade under different factors were analyzed through laboratory model test and numerical simulation,combined with the theoretical formula,the long-term stability of double layer subgrade are calculated.Firstly,indoor model test was carried out.Based on two kinds of crust layer thickness,respectively analyzed three factors,which including the car load,loading speed and running times,studyed the rule of subgrade deformation test of double layer under different factors and the test data of mechanical level,studied the development regularity under the vehicle load in soil.Secondly,using Fortran language to write the Dload subroutine for applying half sine dynamic vehicle load,adopting nonlinear finite element software ABAQUS to establish three-dimensional entity model,analyzed the deformation characteristics of Subgrade under vehicle loads and the dissipation of excess pore water pressure variation in different shell thickness,different loading speed and different wheel axle load.Finally,based on the indoor model test and numerical simulation results,combined with the finite element strength reduction principle,analysed the deterioration analysis on soil properties,derived the relationship between the deduced parameters of the soil and the safety factor and deduced the mathematical expression of safety factor and the number of runs at last,established the long-term stability of subgrade and running times of one-to-one relation and,meanwhile,the quantitative parameters influence on Subgrade stability.