High fill slope collapse: Stability evaluation based on finite element limit analyses

The stability of high fill slopes, which are typically encountered when building airports in mountainous areas, is influenced by complex geotechnical profiles, the fill strength, reinforcement, and rainfall conditions. On 3 October 2009, a catastrophic landslide occurred at Panzhihua Airport in Sichuan Province, China. Investigations indicated that this event was attributable to the presence of carbonaceous mudstone. However, the overall stability of the high fill slope in different construction phases has not been explored. In this study, finite element limit analyses were performed to examine the overall stability of a critical section of the high fill slope in 11 cases that differed in terms of their strength parameters, reinforcement, and rainfall conditions. The results indicate that the original slope stability determined using parameters based on the laboratory shear tests of fill materials was overestimated. Furthermore, the original slope reinforcement with three rows of stabilising piles was ineffective. The safety factor of the pile-reinforced slope was computed to be 0.95 when rainfall infiltration was considered, and the predicted slip surface coincided with the actual failure surface. Random field limit analyses of this slope indicated that the failure probability increased under the assumed rainfall infiltration conditions. Remediation plans could ensure stability against landslides. Overall, reliable parameters and methods must be used to calculate the stability of high fill slopes.