Study on Force Characteristics of Jacked Pipes Under Construction of Large-Diameter and Spatially C-Shaped Curve Tunnels

Taking power tunnels as research objects, the field measurement was conducted to study and analyze the force characteristics of jacked pipes under construction of a large-diameter, long-distance and spatially C-shaped curve. The results showed that: in the case of pipe sections in full contact with slurry, the total thrust had few relations with the cumulative jacked distances, and the thickness of overlying soil had an effect on the contact pressure of pipe walls, but the grouting pressure was the dominant factor; the stress in circumferential rebas was mainly in compression, pipe sections was in compression on the inside and in tension on the outside, and the diameters at the ends of pipe sections were compressed to "ellipsoid"; the longitudinal rebars in the left and upper parts of pipe sections were in compression, as well as the rebars in the right and lower parts of pipe sections were in tension, and the pipe sections were deflected under the action of bending moment and the middle part of the pipe sections deflected to the right. Thus, the reasonable distribution of rebars and increasing prestressed rebars could optimize the pipeline design, improve pipeline performances and economic benefits.