Abstract:

he safety of the shieldbored tunnel structures is jeopardized because the construction of the adjacent deep foundation pits affects the bending moment and deformation of the shieldbored tunnels. In order to evaluate and protect the shieldbored Metro tunnels, it is necessary to study the control values of the bending moments and deformations of the tunnels. Huangsha～Changshou Road tunnel on line 1 of Guangzhou Metro is taken as engineering example in the paper. First, the control value of the bending moment of the segment lining of the shieldbored tunnel is calculated and the stress on the shieldbored tunnel structure is evaluated on basis of the dimension, rebar arrangement and joint bolts of the segment ling; secondly, the relationships between the longitudinal deformation curvature of the tunnel and the circumferential joint openings of the segment lining is analyzed by using an equivalent axial rigidity model for shieldbored tunnels and a simple calculation method for the segment joint openings; thirdly, control values are recommended for the deformation of the shieldbored tunnel on basis of the shieldbored Metro tunnel protection experience and segment ring model test results; finally, the safety of the studied tunnel is evaluated and suggestions are made on the monitoring of the tunnel deformation on basis of the 3D deformation monitoring results of the tunnel. The study can be used as guidance for the protection of other shieldbored Metro tunnels affected by construction of adjacent underground works in the future.

Key words: tunnel, shieldbored tunnel, bending moment, deformation, control value, joint opening, safety evaluation, data analysis