地铁明挖上接增层施工既有车站及围护结构变形规律研究OA

When a zero-distance open-cut excavation is conducted above an existing underground structure,excavation-induced unloading can cause significant deformation of both the existing structure and the retaining system.To clarify the deformation behavior induced by the zero-distance excavation,the Pingguoyuan Station of Beijing Metro Line 6 was taken as a case study,and a combined approach of field monitoring and numerical simulation was adopted.The deformation mechanisms of the existing station and the retaining structure during the excavation were systematically analyzed.The results indicte that:with the increase of the excavation depth,the station roof exhibits a nonlinear accelerated uplift,while the horizontal displacement of the retaining structure shows pronounced abrupt variations.To control the uplift of existing station,measures including lateral soil grouting to increase resistance,zoned excavation,and connection between pile foundations and the station base slab were proposed,successfully limiting the maximum uplift to 2.82 mm.For displacement control of the hanging piles,embedding the pile bases into the existing station combined with reserving counter-pressure soil was shown to effectively restrain pile-base displacement and mitigate pile sliding tendencies.