Study on Overlying Pipelines Deformation Induced by Tunnel Excavation Based on Transparent Soil Test

The influence of tunnel excavation on the overlying pipeline cannot be ignored when the distance between the pipeline and tunnel is minor. For the special condition of tunnel excavation through the existing pipeline, the transparent soil and PIV technologies were adopted to conduct a comparative study on the deformation regularities of continuous and non-continuous pipelines. The dynamic change of soil displacement with tunnel excavation was monitored, and the influence of bending stiffness, depth and section length of pipelines on their deformation was analyzed by the control variable method. The results show that: The settlement patterns of both continuous and non-continuous pipelines are basically consistent with the Gaussian settlement curve. The maximum settlement value of continuous pipeline decreases with the increase of flexural stiffness and increases with the increase of pipeline burial depth. The maximum settlement value of discontinuous pipeline increases first and then decreases with the increase of pipeline section length. In addition, the relative position between the non-continuous pipeline and tunnel has a significant impact on the pipeline settlement. When the non-continuous pipeline interface is directly above the tunnel axis, its maximum settlement value is significantly higher than those value when the tunnel axis is directly below the pipeline joint center, indicating that the tunnel crossing position close to the non-continuous pipeline interface is the most dangerous situation which should be avoided as soon as possible in design.