Mechanical Behavior of the Special Segment Structure during Upward Shield Tunnel Construction

Abstract

The upward shield method in horizontal tunnels has the advantages of small ground space occupation, low construction cost, and short construction period, which expresses substantial economic benefits. The special segments of horizontal shield tunnels corresponding to the upward shield method construction area have special design requirements, and different internal force calculations and analyses should be carried out. To determine the mechanical behavior of the special segment structure of horizontal shield tunnels during the construction of upward shield tunnels, the theoretical calculation formula of the internal force of the special segment structure is deduced based on the average uniform rigidity ring method. Moreover, the bending moment and axial force of special segments are numerically simulated and analyzed using Midas GTS NX software. Finally, the theoretical formula and finite element calculation results are compared and analyzed. The results show that the internal force values of the open segment ring and the adjacent segment ring of the special segment are quite different during upward shield tunnel construction. Furthermore, compared with the arch crown and arch bottom of the segment ring, the stress at the arch waist of the segment ring is the most unfavorable. The stress difference between the open segment ring and the adjacent segment ring may cause unbalanced deformation, leading to damage to the segment ring radial joint. In the design and construction, attention should be given to the shear strength of the segment ring radial joint and the bending stiffness of the ring joint at the arch waist.

Effects of Jack Thrust on the Damage of Segment Lining Structure during Shield Machine Tunnelling

“…Takeuchi et al [24] explored the impact of jack thrust on segment stress using field tests, fundamental laboratory experiments, and three-dimensional finite element analysis methods. Lu [25] elucidated the damage mechanisms of diseased segments and ascertained and validated the crack distribution and propagation patterns of lining segments under various construction loads. Yang et al [26] examined the damage mechanisms of shield tunnel segments on three scales: a single segment, two segments (including joints), and a whole-ring lining structure.…”

A General Framework for the Impact of Shield Tunnel Construction on Existing Tunnel in Soil

“…To solve the problem of ground subsidence and the inclination of buildings on both sides caused by subway shield tunnel construction regarding the first building, the numerical simulation method was used to analyze the influence of the shield tunnel construction on the adjacent buildings and their pile foundations (Li et al [14]). To determine the mechanical behavior of the special segment structure of a horizontal shield tunnel during the construction of an upward shield tunnel, Lu et al [15] deduced a theoretical calculation formula of the internal force of the special segment structure based on the average constant stiffness ring method, using Midas GTS NX software. A numerical simulation analysis of the bending moment and axial force of the special segment was conducted.…”