Evaluation Of Service Performance Of High-speed Railway Subgrade In Cold Region Based On Probability Finite Element Method

As one belt,one road and the western development strategy are being pushed forward,the pace of high-speed railway construction is accelerating,and the scale and difficulty of construction are increasing.The construction of high-speed railway in the northeast,northwest and other cold regions is faced with the problems of high-speed railway infrastructure construction and maintenance under severe cold conditions,especially the construction and maintenance of frozen soil subgrade.Based on the engineering background of Harbin Dalian high-speed railway subgrade,this paper studies the uneven settlement deformation of subgrade caused by the change of environmental temperature,external load and spatial variability of soil material parameters.Through theoretical analysis and numerical simulation,the temperature field and deformation field of subgrade soil under the influence of environmental temperature and solar radiation are established.Based on the probabilistic finite element method,this paper analysed the influence of various random factors on the subgrade settlement and deformation,and finally puts forward the evaluation system for the service performance of high-speed railway subgrade structure in cold regions,so as to provide some guidance for the later maintenance and operation of high-speed railway subgrade in cold regions.The research contents and conclusions are as follows:(1)Considering the environmental temperature,solar radiation,ground effective radiation,wind speed and other factors that affect the heat conduction of subgrade soil,the temperature field of subgrade within 30 years of service is established through theoretical analysis and numerical simulation.The results show that with the passage of time,the environmental temperature gradually increases,and the freeze-thaw depth of subgrade gradually becomes shallow.Then,the temperature field is introduced into the corresponding seepage consolidation field to calculate the deformation of permafrost subgrade under the coupling effect of water and heat,and the influence of train load during the operation of high-speed railway subgrade is fully considered to predict the subgrade deformation in the next 30 years.(2)A reliability analysis method based on stochastic finite element analysis of highspeed railway subgrade deformation is established.Based on the knowledge of reliability theory,the probability distribution form and value of random parameters of subgrade soil are determined,and the sampling method is determined to simulate the spatial variability of soil material parameters.By combining ABAQUS-Python secondary development and MATLAB programming,the random field model is established.The results reveal the influence of random parameters on the settlement and reliability of frozen soil subgrade.The results show that the existence of the worst correlation distance makes the mean settlement and failure probability of the subgrade reach the maximum,and the Poisson’s ratio in the soil parameters has more significant influence on the mean settlement than the elastic modulus and the soil density.(3)The reliability analysis method of high-speed railway subgrade deformation based on probabilistic finite element method is established.Based on the previous research results,a more practical parameter model is established.Through the calculation and analysis of subgrade settlement deformation,the long-term service performance of subgrade is predicted,and the corresponding improvement measures are put forward.