城市地下隧道近接既有铁路桥梁桩基施工力学行为分析

Analysis on Mechanical Behavior of Pile Foundation Construction of Urban Underground Tunnel Close to Existing Railway Bridge

以某穿越铁路桥梁基础工程为研究对象,通过理论分析、数值模拟的方法,分析盾构在穿越过程中桩基的位移、弯矩、地表沉降规律。结论如下:桩基横向位移与弯矩的变化主要集中在盾构隧道所在深度;桩基距离盾构隧道越近,横向位移与弯矩变化越明显;两隧道间的桩基弯矩远大于隧道两侧的桩基弯矩;两隧道间的桩基随着右线、左线的开挖,弯矩与位移表现先增大后减小的变化趋势,并在右线隧道完全贯穿桩基础时位移、弯矩最大,最大值约为工程开挖完成后的3~4倍。

Taking a bridge foundation project across a railroad as the research object,the displacement,bending moment and surface settlement law of pile foundation during the shield crossing are analyzed by means of theoretical analysis and numerical simulation.The conclusions show that the changes of transverse displacement and bending moment of pile foundation are mainly concentrated in the depth where the shield tunnel is located.The closer the pile foundation is to the shield tunnel,the more obvious the changes of transverse displacement and bending moment are.The bending moment of pile foundation between the two tunnels is much larger than the bending moment of pile foundation on both sides of the tunnel.The pile foundation between the two tunnels shows the change trend of increasing and then decreasing bending moment and displacement with the excavation of right line and left line.And the displacement and bending moment are the largest when the right line tunnel completely penetrates the pile foundation.The maximum is about 3~4 times after the excavation is completed.