【作者】 吴江；

【导师】 张良；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2017， 硕士

【摘要】 桩板墙是由锚固桩演变而来的一种支挡结构,具有施工便捷、地基承载力要求不高、收坡效果好及减小填挖工程量等优点,使得桩板墙在高陡边坡地段支挡结构工程中得以广泛应用。目前,国内对于高速铁路桩板墙的设计方法依然沿用普速铁路支挡结构设计规范,要求桩顶侧向位移不超过悬臂段的1%,且小于10cm。但是由于墙体侧向变形会引起墙后填土产生附加沉降,而且高速铁路无砟轨道路基面工后沉降变形规定为不超过15mm,使得目前设计方法的变形控制标准对高速铁路无砟轨道桩板墙设计的适用性有待考证。桩板墙设计载荷中由列车动荷载引起的土压力是按弹性理论计算的,其并没有考虑墙体侧向位移的影响。因此,研究高速铁路无砟轨道桩板墙侧向变形与其引起的路基面附加沉降的关系及适用于高速铁路无砟轨道的基于变形控制的设计方法中列车动载引起的土压力设计值的控制,是具有现实意义的。在总结与分析现有桩板墙研究成果基础上,以贵广高速铁路无砟轨道陡坡地段路肩桩板墙典型工点为原型,结合现场实测数据,以数值分析为研究手段,分析了桩板墙承载力特性随结构参数、地基条件等因素变化的敏感性;讨论了锚固桩侧向位移对墙背土压力和路基面沉降影响的规律;研究了列车荷载产生的墙背土压力分布规律,提出了路肩桩板墙承受列车作用的等效条形荷载模式,主要成果如下:(1)以现场工况的数值模型为基准,对桩板墙悬臂段长度、桩前地表坡度、地基强度、锚固桩的锚固条件、桩间距及锚固桩截面尺寸等影响因素进行了敏感性分析;通过人为控制桩板墙锚固桩的侧向位移,分析了墙背土压力及路基面沉降与锚固桩侧向位移的关系,结果表明,墙背土压力沿墙背呈先增大后减小的分布形态,最大值出现在墙顶以下3.5～4m之间;墙顶侧向变形引起的路基面附加沉降沿路基横断面近似呈三角形分布,其影响范围在6～7.5m左右,约为桩径的3～3.7倍;现场工点墙顶侧向位移s与近墙轨下路基面沉降e的解析关系为e=0.13s,墙体侧向位移引起的工后路基面附加沉降仅占工后沉降允许值得1.4%。(2)探讨了仅考虑单个转向架条件下,锚固桩对列车荷载作用下最大墙背土压力值的影响;在此基础上,讨论了列车轴重、速度及数量对列车荷载作用引起的土压力大小及其沿墙高分布规律的影响;提出了列车作用的等效条形荷载模式。结果表明,锚固桩位置对列车荷载作用下引起的最大墙背土压力值及其分布规律影响较小;列车轴重及数量对墙背土压力值与锚固桩侧向变形量影响显著,但对分布规律无影响;由单线列车荷载作用引起的土压力合力与其对桩前地基表面弯矩的理论值同数值解的比值分别为3.25与2.36,双线荷载条件下的比值分别为4.13与3.02;建议在单线线路路基桩板墙设计时,列车作用的等效条形荷载取规范值的0.3～0.45倍,双线条件下取0.25-0.33倍。更多还原

【Abstract】 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.更多还原