Mechanical performance evaluation on prefabricated steel supporting shaft beneath highly populated urban area based on field test

Prefabricated steel supporting structure (PSSS) is widely used for temporary shaft excavation. Yet, the mechanical response during shaft excavating beneath highly populated urban area was largely unknown. In this paper, the mechanical performance of PSSS was investigated. The internal relationship between the ground settlement and the deformation of the supporting structure was explored by analysis of field monitoring data and numerical simulation results. The findings indicate that the ground settlement was mainly caused by the interaction between the deformation of PSSS and ground stress within the 11 m in the south-north direction and 16 m in the east-west direction. Beyond these ranges, surrounding environmental factors are the main factors for settlement variation. The deformation of the PSSS within the depth of 13.5 m was mainly caused by the ground settlement. The deformation of the PSSS with depth greater than 13.5 m was mainly affected by ground stress and groundwater. As the supporting structure of the shaft, the PSSS can meet the requirement of safety support in densely populated areas of urban infrastructure. The successful application of the PSSS can provide an important reference for the design and construction of other temporary shafts. And the modeling method and selection of constitutive model provide a way for the study of PSSS projects in the similar geological condition.