Abstract:The construction of excavated tunnel in urban core area is increasingly restricted by the factors, such as the removal of underground pipelines. The reasonable subdivision and subzone design is of great significance to the feasibility and progress of the project. Taking an excavated tunnel project in Shanghai as an example, the transverse subdivision construction method along the strip foundation pit is adopted to avoid the present 110 kV electrical pipeline. The longitudinal construction joints are set up near the point of inflection in the super large span section to realize the two-stage pouring of the main tunnel structure, and a series of measures such as temporary partition wall, temporary ribbed plate, temporary corbel and transfer belt are taken to realize the conversion of the two-stage construction structural system, which ensures the safety of deep foundation pit. The rationality of selecting the location of longitudinal construction joint is verified through the analysis on the structural stress, which can provide the reference for the implementation of similar projects in the future.
