Simple Method for the Safety Evaluation of Underground Pipelines Induced by Urban Shallow Tunneling

Excavation of urban-shallow buried tunnel would cause adverse effects on above or neighboring undergound pipelines, even leads to major accidents. According to the joint connection and deformation rigidity, municipal pipelines are divided into the flexible pipeline and the rigid pipeline. Based on the pipeline failure modes, safety criteria of various underground pipelines are discussed. Through the commonly accepted formula of soil movement induced by tunnelling, this paper proposes a simple method on safety evaluation of the flexible pipeline, and gives a case of engineering application, which takes into account spatial position relations between the pipeline and tunnelling, and deformation curve shape of the flexible pipeline. The calculation formula has fewer parameters to be used easily, especially suitable for quantitative safety prediction of underground pipelines in a condition that there are no enough formation datas and detailed pipeline informations before tunnelling. And it also provides a theoretical support for reasonably determining the limit alarming value of ground settlement in tunnel construction.