Analysis of disaster risk to oil and gas pipelines and the effect of CFG reinforcement on high-fill slopes in Yunnan

The study aims to investigate the stability of high fill slopes and their impact on oil and gas pipelines at the foot of the slopes in a key construction project located in Anning City, Yunnan Province. The project formed a high fill slope with a length of nearly 1.6km and a maximum height of about 42 m in early 2023. Due to site planning constraints, four oil and gas pipelines were buried parallel at the foot of the high-fill slope, with the closest pipeline being only 7 m away from the foot of the slope, posing a serious threat to the safety of the oil and gas pipelines. FLAC^3D software was employed to analyze the influence of the fill slope on the pipelines at the foot of the slope, and to explore the stability of the slope with the installation of five rows of CFG piles at the toe. The results show that the potential failure surface exists only within the artificial fill, above the oil and gas pipelines. The basic stability factor of the fill slope is 1.305, indicating basic stability under extreme rainfall conditions. Under natural conditions, the pipeline meets the stability requirements, but may lead to deformation and rupture under heavy rainfall conditions. With the addition of five rows of CFG piles at the slope toe, pipeline deformation and ellipticity meet the specification requirements under heavy rainfall conditions, and the safety and stability coefficient of the slope increases by 4.2%, yet fails to meet the specification safety reserve requirements. Further preventive measures are recommended to ensure the safety reserve of the fill slope.