Quick Assessment on Impact Stress Over Buried Pipelines Due to Rockfall

Abstract

Rockfall is one of the typical geological disasters for mountainous areas that threaten both human activities and engineering buildings. Buried oil and gas pipelines are large linear project as well as high-risk ones commonly exposed to rockfall. Hence, providing a quick assessment method for the harmfulness of impact load by means of field investigation of the rockfall size will help manage and prevent from collapse disaster along pipelines. In this paper, additional stress on pipelines caused by rockfall impact is tested following the similarity principle and taking into account the four basic parameters of rock mass per unit area, fall height, deviation distance and the depth of burial. In the test, thin-walled copper tube is employed instead of a pipeline and the tube internal pressure is not included. According to the effect of these parameters and the tested additional stress on the tube under different loads, the parameters are fitted by product method and converted according to the similarity principle before an ideal quick assessment method for additional stress on pipelines is worked out. On the basis, this method is applied to case study of pipeline deformation caused by SX-1 rockfall. The impact load is also calculated using the Hertz collision theory. The assessment results from the two methods are agreed well with each other. It offers a new guideline for quick assessment of rockfall impact load on buried pipelines as well as a quick assessment method for the safety of buried pipelines.