Analysis the Causes of the Slip Embankment Protecting the Slope of Lien Chieu Aviation Petroleum Depot

The slope protection embankment of Lien Chieu aviation petroleum depot was built in 2001. The embankment is responsible for ensuring safety for the oil tank area and dispensing area, with the capacity of dispensing 13,800 m3 of fuel serving airports in the central region, from Hue to Binh Dinh provinces. In 2008, due to the occurrence of floods, a landslide has destroyed the entire 59.7 m middle segment of longitudinal embankment, leaving the foundation inert. The rest of the embankment body in the North was cracked on the entire surface; the embankment body fell inward; the weight relief plate was cut entirely from the embankment body and collapsed downwards. The collapse of the slope embankment led to the destruction of the oil tanks, causing the operation to stop. It was urgent at that time to investigate the causes of the slope failure and suggest the safe remedial design for the structure. The site investigation and numerical analyses show that the reasons for the failure could be due to the insufficiency of drainage holes to drain groundwater during the flood season characterized by heavy rain, which made the lateral pressure acting on the wall increase significantly, possibly causing the wall structure to be damaged. The proposed design which consists of a low retaining wall and upper slope embankment, both reinforced by geotextiles, could be stable according to numerical modelling with many loading cases. Attention must be paid to the stability of the excavation slope during construction and the difficulties of narrow space for the excavation.