盾构下穿铁路路基钢轨变形及路基沉降分析

Analysis of track deformation and subgrade settlement of shield tunnel construction crossing existing railway

为研究地铁盾构下穿铁路路基过程中钢轨变形与路基沉降的变化规律,分析路基深孔注浆的加固效果,基于天津地铁7号线盾构施工下穿某铁路工程,采用有限元软件Midas-NX对盾构下穿既有铁路过程进行动态模拟,分析了盾构穿越过程中有无深孔注浆时钢轨的水平与竖直变形,以及盾构施工完成后铁路路基竖向位移的分布规律.结果表明,钢轨的横向变形经历了两次先增后减的过程,并沿轨身呈对称分布;钢轨变形在盾构两次到达铁路正下方时达到极值,沿轨身沉降槽中心随施工步骤逐渐向工程中心移动;土层经深孔注浆加固后,钢轨的横、竖向位移以及路基沉降分别减小了85.1%、76.7%和74.1%,有利于保证铁路在地铁盾构过程中的安全性.

To study the changes of track deformation and subgrade settlement of the shield tunnels across the existing railway,and to analyze the reinforcement effect of deep hole grouting in subgrade,we carry out the dynamic simulation by using the finite element software Midas-NX based on the shield construction of Tianjin Metro Line 7. We analyze the horizontal and vertical deformations of the rail and the distribution of the vertical displacement of the railway subgrade after the completion of the shield construction. The results show that the transverse deformation of the rail undergoes two processes of enlargement first and then decreases with the construction progress,and forms a symmetrical distribution along the rail body; the rail deformation reaches the extreme value when the shield reaches the bottom of the railway for two times,and the center of the settlement trough along the rail gradually moves to the engineering center with the construction step. After reinforced by deep hole grouting,the lateral and vertical displacements of the rail and the settlement of the roadbed reduce by 85. 1%,76. 7% and 74. 1%,respectively,which is beneficial to ensure the safety of the railway in the subway shield process.