跨地裂缝带云轨桥梁结构变形与力学特征

Structure Deformation and Force Characteristics of Skyrail Bridge Crossing Ground Fissure Zone

地裂缝作为西安市典型城市地质灾害,给城市交通建设带来了巨大潜在危害,引起工程界的高度关注。以西安市高新区云轨示范线工程跨地裂缝带为研究背景,基于有限元数值模拟,分析了云轨简支梁桥正交跨越地裂缝带轨道梁、桥墩及桩基础等结构的变形与受力特征。结果表明:地裂缝错动作用导致云轨轨道梁产生竖向沉降差异,跨地裂缝段竖向位移差异和水平位移最大,其水平位移最大约为地裂缝位错量的1/4;桥墩出现竖向沉降,且向地裂缝带倾斜,其顶部水平位移上盘大于下盘,水平位移最大约为地裂缝位错量的1/3;地裂缝两侧桥梁桩基础产生以水平位移为主的倾斜变形,土体对下盘桩产生正摩擦力,对上盘桩产生向下的负摩擦力,下盘桩受压,上盘桩受拉。上述研究结果可为桥梁跨地裂缝带工程设计与防灾减灾提供参考和指导。

As a typical urban geological disaster in Xi’an, the ground fissure brings great potential harm to the local traffic construction, which attracts the attention of engineering scholars. Taking the skyrail engineering in Xi’an high-tech zone crossing ground fissure zone as the research background, based on the finite element numerical simulation, the structure deformation and force characteristics of the track beam, pier and pile foundation were analyzed. The results show that under the action of ground fissure dislocation, the vertical settlement difference of skyrail track beam is caused, and the vertical displacement difference and horizontal displacement crossing ground fissure section is the largest, and the maximum horizontal displacement is about one quarter of ground fissure dislocation;the vertical settlement of pier is inclined to ground fissure zone, and horizontal displacement in the top of hanging wall is larger than that in footwall, and the maximum horizontal displacement is about one third of ground fissure dislocation;the deformation of bridge pile foundation results in inclined deformation dominated by horizontal displacement;the soil produces positive friction to footwall pile and negative friction to hanging wall pile;footwall pile is under pressure while hanging wall pile is under tension. The above results can provide a reference and guidance for the engineering design, disaster prevention and mitigation of bridge crossing ground fissure zone.