钻孔灌注桩围护条件下基坑开挖对邻近地铁隧道结构变形的影响

Influence of Foundation Pit Excavation on Deformation of Adjacent Subway Tunnel Structure Under Bored Pile Retaining Support Condition

依托绍兴古城入口改造提升项目基坑开挖工程实例,采用数值模拟结合现场实测的手段,研究钻孔灌注桩+钢筋混凝土支撑围护结构条件下,基坑分层开挖对在建地铁隧道结构变形的影响。结果表明:基坑开挖各工况完成时,地铁隧道累计竖向位移量、累计水平位移量均未超过预警值,钻孔灌注桩+钢筋混凝土支撑的围护形式满足邻近地铁隧道条件下基坑开挖对地铁隧道的变形控制要求。基坑开挖引起的地铁隧道竖向位移及水平位移实际值与数值模拟预测结果较为接近,可采用该有限元模型进一步进行围护形式优化研究。

Relying on the example of the foundation pit excavation project of the Shaoxing ancient city entrance renovation and upgrading project,numerical simulation combined with field measurements are used to study the influence of the layered excavation of the foundation pit on the structural deformation of the subway tunnel under the conditions of the bored pile and reinforced concrete retaining support structure.The results show that the cumulative vertical displacement and cumulative horizontal displacement of the subway tunnel do not exceed the warning value at the completion of each working condition of the foundation pit excavation,and the retaining support form of the bored pile and reinforced concrete retaining support meets the deformation control requirements of the subway tunnel under the conditions of the adjacent subway tunnel by the foundation pit excavation.The actual values of vertical and horizontal displacements of the subway tunnel caused by foundation pit excavation are close to the predicted results of numerical simulation,and the finite element model can be used for further research on the optimization of the retaining support form.