Abstract: To study the influence of tunnel construction on the behavior of underground pipelines, this paper presents a modification to the formula for calculating the pipeline deformation based on the Winkler elastic foundation beam theory and previous related results. We also give an explicit solution in single line tunnel case and a new method of solving for the mechanical responses such as the bending angle, bending moment and shear force of an underground pipeline. The method is verified through calculations using MATLAB. By the superposition principle, we derive a method for direct calculation of the mechanical responses of a pipeline subjected to the construction of twin tunnels in parallel. Results show that the responses of such a twin tunnel case are significantly different from those of the single line tunnel case, and that the spacing of twin tunnels is a major factor influencing the responses. When the spacing is varied, the distributions of deformation and bending angle of the pipeline are nearly the same, but the peak magnitudes are always larger than those of single line tunnel case. And there exists a certain range of the spacing, beyond which the peak bending moment and peak shear force are larger than those of single line case. Within this range, both appear smaller. This study provides an effective method for calculating the mechanical responses of underground pipelines to ground movement under construction of single and twin tunnels, thereby helping safety evaluation of urban underground pipeline operation.

Key words: underground pipeline, tunnel construction, tunnel-pipe-ground interaction, explicit solution