A Study on Deep-Seated Stability of Geotextile Reinforced Earth Embankment

The current study discusses geotextile-reinforced earth embankment deep-seated failure characteristics. Federal Highway Administration (FHWA) suggests that deep-seated failure analysis must be performed to check that the slip surfaces beyond the reinforced zone have an adequate factor of safety. Two problems, i.e., a homogeneous soil embankment and a stepped embankment, have been studied for deep-seated failure analyses. A spreadsheet platform has been developed using Visual Basic programming code to perform the task of determining the top reinforcement length, the length for safe reinforcement against pull-out failure, and the tensile maximum force to be resisted by the geotextile reinforcement for achieving the target factor of safety considering the rotational failure mechanism of the embankment based on Bishop's simplified method. The bottom reinforcement length is determined considering the failure to be initiated through the sliding mechanism at its base. The deep-seated failure behaviour of two embankments under pore water pressure loadings has been examined. It is observed that the bottom reinforcement length determined through the sliding failure mechanism may not always meet the deep-seated failure criteria laid out by FHWA. It is then necessary to incrementally alter the bottom reinforcement length until the deep-seated failure standards are met. It is further noticed that when the soil has higher strength properties, the deep-seated failure criteria are satisfied for relatively smaller values of bottom reinforcement length. A composite deep-seated failure behaviour for the entire steep embankment has also been inspected to check whether all the slip circles beyond the reinforced zones of the upper and lower parts of the embankment meet the deep-seated failure criteria.