桥梁桩基础施工对既有高速铁路桥梁基础变形的影响

Influence of Bridge Pile Foundation Construction on Bridge Foundation Deformation of Existing High Speed Railway

衡茶吉铁路(衡阳—茶陵—吉安)正线在DK211+000—DK212+100与武广高速铁路并行。利用FLAC 3D建立了三维有限元模型,模拟了衡茶吉铁路竹山屋中桥桥梁桩基础开挖的施工过程,分析了新建铁路桥梁桩基础开挖对桩围土体和既有武广高速铁路竹山屋特大桥基础的影响。结果表明:新建铁路桥梁桩基础开挖过程中地表土体的水平位移小于15 mm,竖向位移小于7 mm;桩基础开挖深度与周围土体的变形成反比,在桩基础上部影响范围约为桩径的3～5倍,中下部约为桩径的1～2倍;新建铁路桥梁桩基础开挖对既有武广高速铁路竹山屋特大桥桥梁变形影响较小,其水平和竖向几何偏差远小于规范限值,基本不影响既有桥梁的安全。

Hengchaji railway(Hengyang-Chaling-J i an)is parallel to Wuhan-Guangzhou high speed railway at DK211+000-DK212+100.A three-dimensional f inite element model was established by using FLAC 3D,the construction process of pile foundation excavation of Zhushanwu middle bridge in Hengchaji railway was simulated,the inf luences of pile foundation excavation of newly-built railway bridge on pile surrounding soil and foundation of existing Zhushanwu super-large bridge in Wuhan-Guangzhou high speed railway were analyzed.The results show that horizontal displacement of surface soil is less than 15 mm and vertical displacement is less than 7 mm during pile foundation excavation of newly-built railway bridge.The excavation depth of pile foundation is inversely proportional to the deformation of surrounding soil,the inf luence range on upper part of pile foundation is about 3~5 times of pile diameter,and inf luence ranges on middle part and lower part are 1~2 times of pile diameter.The pile foundation excavation of newly-built railway bridge has little inf luence on the deformation of the existing Zhushanwu super-large bridge in Wuhan-Guangzhou high speed railway,the horizontal and vertical geometric deviations are far less than the specif ication limit and basically do not affect the safety of existing bridge.