Abstract
At present, there is no clear design standard for segmental joints of large-diameter shield tunnels under high water pressure. In this paper, a theoretical calculation model for the bending stiffness of segmental joints under high water pressure is proposed. The numerical simulation method is used to investigate the failure and crack formation processes of single-layer and double-layer lining segments under large axial forces. The effects of axial force, bolt strength, and concrete strength on the bending stiffness of joints are then studied using a theoretical calculation model of segmental joints. The results show that under extremely high water pressure, the influence of double lining on joint stiffness is limited. It is more rational and safe to compute the bending stiffness of segmental joints using this theoretical model rather than the numerical simulation method. The parameter analysis reveals that increasing the bolt strength has a minor impact on bending stiffness and deformation, whereas increasing the concrete strength has the opposite effect. The influence of ultimate bearing capacity and deformation decreases non-linearly as the axial force increases.
Highlights
Introduction under Ultrahigh Water PressureTunnels play an essential role in the transportation infrastructure
In the process of increasing the axial force from 12,000 to 14,000 kN, the ulthe process of increasing forcebending from 6000 to 8000increased kN, the ultimate bearing timate bearing capacity ofthe theaxial positive moment by 4%, while thecapacnegaity of the positive bending moment increased by 19%, the ultimate capacitydeof tive bending moment increased by 7%; the positive bending moment bearing limit curvature negativeby bending moment increased by 24%; the ultimate curvature creased
It can be seen that the ultimate bearing capacity and ultimate deformation under negative bending moment conditions are more sensitive to the increase of axial force
Summary
The flat-shaped segment is used instead of the actual arc-shaped segment. Water and soil 0pressure is the axial force exerted on the segment. There are and six soil groups of axial-force-loading conditions. The vertical force axial load inWater pressure is the axial force exerted on the segment. The horizontal creases by kN each time until the concrete of the joints crushes, or the bolt pulls force loading ranges from 10,000 to 20,000 kN, and the load increment value is 2000 kN.out. Double-layer lining is load shown in Figure are diagram six groupsofofsingle-layer axial-force-loading. 2003kN each time until the concrete ofof thethe joints crushes, orlining the boltsegment
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