Effects of Construction Sequences and Volume Loss on Perpendicularly Crossing Tunnels

Abstract

The number of constructed tunnels has been gradually increasing for the past decades due to rapid development in urban areas. However, the soil-structure interaction problems arising from perpendicularly crossing tunnels attract relatively little research attention in the past. In this study, six three-dimensional finite element analyses were conducted to simulate tunnel excavation nearby a perpendicularly crossing existing tunnel, in an attempt to investigate the effects of construction sequences on cross-cutting tunnels. The hypoplastic constitutive model for sand is adopted in the numerical analysis to consider the soil small-strain stiffness. Computed results are presented and discussed in terms of ground surface settlement, displacement and deformation of the existing tunnel, and bending moment induced on the existing tunnel. The stress-transfer mechanism in soil nearby the existing tunnel due to tunnelling is also studied.

Influence of Tunneling in Cohesionless Soil for Different Tunnel Geometry and Volume Loss under Greenfield Condition

“…(vi) Tunnel excavation is simulated by removing the soil located in the excavation zone; i.e., soil is excavated inside the tunnel lining and surrounding the tunnel lining by deactivating the soil element. As for the cases that consider only volume loss without the effect of weight loss, soil is excavated surrounding the tunnel lining only [27]. e excavation of a tunnel leads to stress relief in the soil surrounding the tunnel, and consequently, the soil mass moves towards the excavation.…”