Monitoring And Prediction Of Cumulative Deformation Of High-speed Railway Subgrade Filling Under Cyclic Dynamic Load

In recent years,with the advantages of safety,stability,comfort,convenience and efficiency,high-speed railway has developed rapidly.However,with the continuous improvement of train speed and service life of railway lines,the cumulative settlement and deformation of Subgrade under large-cycle train loads become more and more prominent.Based on the project of National Natural Science Foundation of China(No.51508489),this paper takes graded gravel(B-aggregate)high-speed roadbed filler along the WuhanGuangzhou high-speed railway as the research object,carries out the deformation monitoring test of roadbed filler under cyclic dynamic load,and analyses the long-term cumulative deformation development law of roadbed filler under different working conditions.Based on the "mixed model method",the cumulative plastic deformation calculation model of high-speed railway subgrade under large cycle dynamic load is established,and the calculation model is applied to high-speed railway engineering.The long-term cumulative deformation of the subgrade and the whole subgrade structure under the actual driving load is predicted and analyzed.The main research work and results are as follows:(1)Calibration experiments of displacement sensor,acceleration sensor and earth pressure sensor used in deformation monitoring are carried out respectively.The results show that the measured values of displacement sensors are larger than those of micrometers under the same displacement stroke conditions;the amplitude of vibration acceleration will be attenuated by protective measures;and the calibration coefficients of different earth pressure sensors in calibration media will be significantly different.(2)The deformation monitoring test of subgrade filling under cyclic dynamic load is carried out,and the variation laws of vertical elastic deformation,vertical cumulative plastic deformation and lateral cumulative plastic deformation with load number,load level,load frequency and depth at different locations are analyzed.The results show that the vertical elastic deformation increases with the increase of load level,and the relationship is approximately linear;the vertical elastic deformation decreases with the increase of load frequency;the vertical cumulative plastic deformation increases with the increase of load number,and shows obvious development trend with the increase of load level;the elastic and plastic deformation of vertical measuring points and the plastic deformation of lateral measuring points change along the depth direction.The law is basically the same.(3)Based on the mixed model method,a long-term cumulative deformation calculation model of Graded Macadam Subgrade Filling Subgrade Considering the number and level of loading is established.The model parameters are determined by regression analysis of measured deformation data and simulation calculation of filling model.Taking the Wuhan-Guangzhou high-speed railway as the research object,a three-dimensional finite difference model is established to simulate the actual driving load on the Ballastless Track Subgrade of high-speed railway.The long-term cumulative plastic deformation of the subgrade and the whole subgrade under the actual driving conditions is predicted and analyzed with the calculation model.