The corrosion protection problems of shield tunnel pipelines have always been ignored. In this paper, by investigating the corrosion and protection status of 5 shield tunnel pipelines, the corrosion situation of shield tunnel facilities (such as hot-bending bends, straight pipe sections and joint coating, and pipeline steel components of shield tunnels) was analyzed. It was clarified that mechanical damage during the installation of hot-bending elbows was an important source of damage to the anti-corrosion layer. The joint coating method of viscoelastic body and heat shrinkable tape can effectively reduce the risk of joint coating failure, and the sacrificial anodes can inhibit the corrosion of pipeline steel components. By analyzing the current corrosion problems that impact shield tunnel pipelines, one can consider corrosion prevention countermeasures in the overall shield tunnel pipeline design.
At present, there were ten common crossing modes in long-distance oil and gas pipelines[1,2]. There were six ways of tunneling, such as large excavation, horizontal directional drilling, shield tunnel, drilling and blasting tunnel, ramming pipe and pipe jacking. There were four ways of spanning methods, such as truss crossing, arch bridge crossing, suspension cable crossing and cable-stayed bridge crossing. Crossing by shield tunneling, as a pipeline laying method with high mechanization and automation, extensive applicable strata and high safety, has been widely used in recent years. A shield tunnel was dug below the ground by a shield machine, with a support and excavation device in front of the shield machine, and a precast or cast-in-place concrete lining at the tail. For each ring distance advanced by the shield machine, a ring lining was supported or assembled at the tail, and cement slurry was pressed into the void at the periphery of the lining ring. After the excavation was completed, a tunnel capable for laying pipelines was formed.
The different structures that comprise pipeline crossings within shield tunneling structures included originating well, receiving well, S-shaped hot-bending bends, pipeline, and steel support structure, etc. After the shield pipeline was completed, there was fixed piers, concrete supports, and steel supports to ensure the stability of the pipeline. When the pipeline was put into production, shield tunnels were generally filled by water, soil, or foam concrete.
