Numerical Analysis Of Mechanical Characteristics For Sheet-pile Wall On Steep Slope Subgrade Of Ballastless Track In High-speed Railway

Sheet-pile wall is a retaining structure evolved from anchor pile,it has the advantages that convenient construction?the requirement to bearing capacity of the foundation is not very high?good effect of collecting slope and can effectively reduce the amount of excavation and so on,which make it widely used in high and steep slope section of retaining structure in engineering.At present,the domestic design method for high-speed railway sheet-pile wall is still adopting the design code for general speed railway retaining structure,which requires the lateral displacement of pile top is not more than 1%of the cantilever,as well as less than 10cm,but the lateral deformation of wall will cause additional settlement to backfill,besides the requirement to post construction settlement of high-speed railway ballastless track subgrade surface is below 15mm,which makes the applicability of the current standard of deformation control to design high-speed railway sheet-pile wall is to be verified.And according to the elastic theory to calculate the earth pressure induced by train load,which don't consider the influence of lateral displacement of the wall,Therefore,It has practical significance to study on the relationship between lateral displacement of high-speed railway ballastless track sheep-pile wall and the additional settlement of subgrade surface?control of design value of earth pressure caused by train dynamic load when using the design method based on deformation control.Based on the summary and analysis of existing research results on the sheet-pile wall,taking Gui-Guang steep slope shoulder sheet-pile wall of ballastless track in high-speed railway as the prototype of typical sites,numerical analysis as research method combined with field data,in view of numerical analysis by field data,having analysis on the sensitivity of sheet-pile wall structure parameters?relationship between lateral deformation of pile and settlement of subgrade surface and distribution law?theoretical value and numerical value of earth pressure induced by train dynamic load along the back wall,suggesting that the earth pressure caused by train dynamic load need to be reduced when designing the wall with the method based on fast stable deformation state control,and giving the equivalent bar load mode of train load.The main contents are as follows:(1)Based on the numerical model,having sensitivity analysis on the structure parameters——length of the cantilever sheet-pile wall,surface slope,foundation strength,anchorage condition of anchorage pile,pile spacing and pile section size;Studying on the relationships between earth pressure?settlement of subgrade surface and the displacement of pile by artificial control.Results suggested that the earth pressure along wall height increases firstly and then decreases,The maximum value appears at the top of the wall below 3.5?4m;The additional settlement of the subgrade surface caused by the lateral deformation of the top of the wall is similar to that of the triangular cross section,and the influence range is about 6?7.5m,which is about 3-3.7 times of the pile diameter.Analytical relationship between top displacement of wall s and the rail roadbed sinking near the wall under e is e=0.13s,post additional settlement of subgrade surface caused by displacement of wall accounts for only 1.4%of the allowable post construction settlement.(2)Probing into the effect of anchor pile on the maximum wall pressure caused by train dynamic load under the condition of single bogie;discussing the influence of train axle load,speed and the number of train on the earth pressure value and distribution caused by train load;finally;comparing the numerical value of earth pressure resultant force and its bending moment on the ground surface cause by single/double line under the most unfavorable load effect with the theoretical values,giving the reduction range of the earth pressure caused by train load when designing.Results suggested that the position of the pile has no great impact on the maximum earth pressure value and distribution law along the wall back;the train axle load and the number of trains have big influence on the earth pressure and the lateral deformation of the anchor pile,but have no effect on the distribution law;the ratio of theoretical value to numerical solution of earth pressure resultant and the bending moment on the ground surface of the pile cause by single line train dynamic is 3.25 and 2.36 respectively,the ratio of the double line load condition is 4.13 and 3.02respectively;in the design of single line shoulder pile wall,the value of equivalent bar load range is occupied 0.3?0.45 of code value,double line condition is 0.25?0.33.