Study on the Deformation Law of Large-diameter Fully Prefabricated Assembled Shield Tunnels under Ground Surcharge
To meet structural design requirements,a certain deformation space is reserved between the mid-parti-tion wall and the segment lining in large-diameter fully prefabricated assembled shield tunnels.However,during the operation period,the segments and mid-partition wall of the tunnel may come into contact under the ground sur-charge conditions,changing the stress modes of the tunnel structure and posing significant challenges to the safe opera-tion and maintenance of the tunnel structure.In view of this,based on the Shanghai Airport Link Line Tunnel project,a three-dimensional refined finite element analysis model of a large-diameter fully prefabricated assembled shield tunnel was established to analyze the cooperative load bearing and deformation law of the segments and mid-parti-tion wall under the ground surcharge conditions.The study shows that under the ground surcharge conditions,the segments and mid-partition wall of the large-diameter fully prefabricated assembled shield tunnel will come into contact,which will improve the stiffness and bearing capacity of the tunnel structure,but the surcharge can cause damage to the segments and internal components of the tunnel.The bottom of the plate of the arc component,the top of the column cap of the arc component,the outer side of column cap of the arc component,and the bottom of the mid-partition wall are all in a tensile state and are the vulnerable nodes.The damage and failure modes of the tunnel structure are affected by the reserved gap at the top of the mid-partition wall.To improve the bearing capacity of the tunnel,it is recommended to control the gap at the top of the mid-partition wall at about 90 mm.
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