Study on Causes of the "99. 7"Crossing Pipeline Accident in Fuxian County

A natural gas pipeline crossed Luohe River in Fuxian county of northern Shaanxi Province snapped in July of 1999, which produced loss about one million yuan and got solicitude from the Province government and society. This paper, based on established laws of flood erosion, studied the causes of the snap in aspects of the pipeline design and sediment flow conditions. The analysis results have shown that beside unsuitable place where the pipe was buried, the lack of knowledge in the hyperconcentrated sediment flow's behavior is the main cause, resulting in both inadequate pullback weight and inadequate burying depth for the pipe. As a proposal, the behavior of the hyperconcentrated sediment flow must be taken into account when a pipeline is designed to cross a river of large amount of sediments, and especially, a depth of burying should be studied carefully according to scouring of the flow.