Study on the Deformation Characteristics of Small-Radius Curved Shield Tunneling
To investigate the effects of small-radius curved shield tunneling on ground settlement and segmenttal lining deformation,a comprehensive numerical simulation of the excavation process was carried out using ABAQUS.The study examined various curve radii and jack trust ratios to analyze the deformation patterns of the ground surface and tunnel lining.The results indicate that,compared with straight tunnel drives,small-radius curved tunnels experience significantly larger with ground settlement and segmental deformation.The transverse settlement trough in the curved section is asymmetrically distributed and shifts inward toward the curve's center;the smaller the curve radius,the grea-ter both the settlement and the lateral offset.Meanwhile,the horizontal deformation of the vault and arch bottom is relatively insensitive to changes in curve radius,whereas the arch waist is significantly affected.To control uneven ground settlement,it is recommended that the thrustratio between the inner and outer jacks be maintainedbetween 1:1 and 1:2.As theouter-in-ner thrust ratio increases,the maximum horizontal deformation at the outer arch waist grows more than that at the inner side.Accordingly,special attention should be paid to the support and structural design of segmental linings in curved sections to minimize the adverse impact of differential deformation on tunnel safety and stability.
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