地铁暗挖区间下穿市政桥梁桩基托换方案研究

Study on Pile-Foundation Replacement Scheme for Municipal Bridge under Underground Excavation Section of Subway

依托沈阳地铁3号线某暗挖区间下穿文化路立交桥工程,在工期、造价及对周边环境影响等角度对比分析明挖法进行桩基托换与暗挖法进行桩基托换方案的优缺点;从不影响地面交通角度出发,选择暗挖法进行截桩及桩基托换,通过风险分析确定暗挖风险处理措施,保证暗挖施工的安全性,并结合现场实施条件明确了桩基托换施工工序;最后,建立三维有限元模型,计算分析暗挖法桩基托换施工,计算结果表明:暗挖截桩方案施工引起的连续梁绝对沉降、差异沉降、倾斜及水平位移均小于桥梁变形预警值。

Based on the undercut section of Shenyang metro Line 3,the advantages and disadvantages of underpinning schemes of open-cut pile foundation and undercut pile foundation are compared and analyzed in terms of time limit,cost and environmental impact;From the point of view of not affecting ground traffic,the method of undermining is selected to cut piles and underpin piles.Risk treatment measures are determined through risk analysis to ensure the safety of undermining construction.The construction procedure of underpinning piles is defined in combination with the conditions of field implementation;Finally,a three-dimensional finite element model is established to calculate and analyze the underpinning construction of underground excavation pile foundation.The calculation results show that the absolute settlement,differential settlement,inclination and horizontal displacement of continuous beam caused by the construction of concealed excavation and pile cutting scheme are less than the early warning value of bridge deformation.