PBA Construction Technology for Metro Station Expanding Excavation Undercrossing Parallel Existing Structure

Abstract

Objective Affected by the occupation of existing buildings (structures) on the ground, the main retaining piles in shield receiving areas at both ends of some metro stations cannot be built. Therefore, it is necessary to study the pile-beam-arch (PBA)construction technology for expanding excavation of metro station undercrossing the parallel existing buildings or structures. Method With the project of Nijiaqiao Station on New Line 18 in Chengdu Metro undercrossing the existing structures as the research object, a finite element model is established to analyze the subsidence characteristics of the land and the existing structures according to the actual construction plan, and the results are verified by on-site monitoring data. Result & Conclusion PBA construction technologies including advanced large pipe shed, temporary column support system, staggering excavation of 7guiding holes and manual excavation cast-in-place pile are used, successfully implementing the station main retaining pile construction under the premise of effectively controlling the subsidence of land and the existing buildings. The construction steps that have the greatest impact on the above-mentioned subsidence are the excavation of guiding holes 1, 3, 5, 7. The subsidence of existing structures is obvious at guiding holes 1 and 2 with the maximum value of 9.62 mm, 1.5 times the simulated value. Both the on-site monitoring results and the simulated results meet the safety control requirements.

Keywords

• metro station
• pba method
• undercrossing construction
• numerical simulation