摘要
京沪线为国铁Ⅰ级铁路,线间距4.4 m的有砟轨道、双线电气化普速铁路,运营时速160 km/h。本项目热力管道采用顶管的方式先后穿越老京沪线与新京沪线,顶管外径1.8 m,顶管长度108 m,穿越处地层主要为素填土、粉质黏土、粉质黏土夹粉土,顶管距老京沪线的轨道结构的距离为6.31 m,距新京沪线轨道结构的距离为9.03 m。本文建立包括沉井、顶管、京沪线路基、轨道结构及土层的三维有限元模型,来分析顶管施工对铁路的影响,计算结果表明:采用顶管穿越京沪线可以有效地控制沉降,满足铁路运营的安全要求;沉井的变形从上至下逐渐增大,与其受力机理相同;顶管的顶部向下沉降,底部向上回弹,与周边土层变形相协调;铁路路基沉降槽的宽度随覆土厚度的增大而增大,并根据沉降值与基准沉降量的比值分为强烈影响区、显著影响区、一般影响区及无影响区,不同影响区的扩散角与土层等效内摩擦角存在联系;轨道结构的变形为盆式形状,是铁路路基的衍射变形;顶管顶进施工对沉降的影响最大,其他施工步序影响较小。
The beijing-shanghai line is national railway of classⅠwith a distance of 4.4 meters between the two lines,which is a two-track electrified general speed railway with a speed of 160km/h.The thermal pipeline of this project adopts pipe jacking to cross the old and the new beijing-shanghai line one after another,the external diameter of pipe jacking is 1.8 meters and its length is 108 meters,the soil at the crossing point is mainly composed by plain fill and silty clay mixed with floury soil,the distance between the pipe jacking and the track structure of the old beijing-shanghai line is 6.31 meters,and the distance of new beijing-shanghai line is 9.03m.In this paper,a three-dimensional finite element model is established to analyze the influence of pipe jacking passing through the railway,the model includes caisson,pipe jacking,subgrade of the railway,track structure and the soil.The results show that,adopting pipe jacking to cross the beijing-shanghai line can effectively control the settlement and meet the safety requirements of railway operation.The deformation of caisson increases gradually from top to bottom,which is the same with the stress mechanism.The top of the jacking pipe sinks downward and the bottom bounces upward,in harmony with the deformation of the surrounding soil layer.The width of the settling tank of subgrade increases with the increase of the thickness of the overburden,and it divides into strong influence area,significant influence area,general influence area and no influence area according to the ratio of the settlement value to the reference settlement amount.The diffusion angle in different affected areas is related to the equivalent internal friction angle of soil.The deformation of the track structure is in the shape of a basin that diffracted by the subgrade of railway.The impact of pipe jacking on settlement is the greatest,while other construction steps have less impact.
作者
徐威
XU Wei(China RailwaySiyuan Survey And Design Group Co.,LTD.,Xiamen 361010,China)
出处
《四川建材》
2021年第10期146-149,共4页
Sichuan Building Materials
关键词
顶管
下穿京沪线
变形分析
数值模拟
pipe jacking
pass through Beijing-Shanghai railway
deformation analysis
numerical simulation
