Mechanical responses of underground carriageway structures due to construction of metro tunnels beneath the existing structure: A case study

Abstract

To understand the mechanical response pattern of the existing structure and ground due to the construction of metro tunnels underneath, the finite difference method is adopted to study the torsional deformation and stress variation of the existing structure and the effect of underground carriageway structures on the surface subsidence. The curves of the maximum differential subsidence, torsion angle, and distortion of the cross‐section of the existing structure show two peaks in succession during traversing of two metro tunnels beneath it. The torsion angle of the existing structure changes when the two tunnels traverse beneath it in opposite directions. The first traversing of the shield tunnel mainly induces the magnitude variation in torsional deformation of the existing structure, but the second traversing of the subsurface tunnel may cause a dynamic change in the magnitude and form of torsional deformation in the existing structure. The shielding effect can reduce the surface subsidence caused by metro tunnel excavation to a certain extent, and the development trend of subsidence becomes slower as the excavation continues.

Reliability Analysis and Risk Assessment for Settlement of Cohesive Soil Layer Induced by Undercrossing Tunnel Excavation

“…During the construction process, the surrounding aboveground and underground structures, various drainage, rainwater, gas, water supply, communication, electric power, and other underground pipelines and road surfaces are seriously damaged [5,6]. The underground construction of urban subway engineering has the characteristics of strong concealment, poor regularity of spatial distribution, difficult to predict ground collapse, and difficult to assess the impact on the safety of existing structures [7,8]. The distribution range, spatial form characteristics, ground collapse, and the quantification of the safety impact of buildings are the key technical problems that have puzzled engineers and technicians in hazard assessment and the reasonable determination of treatment measures.…”