A Study on Reliability Analysis for Reinforced Earth Retaining Walls

ABSTRACT: Traditionally, the reliability of retaining walls is achieved through the use of safety factors or margins and adopting conservative assumption in the process of design, that is, by ascertaining that a mini-mum supply condition will remain adequate under a maximum demand condition. However that is often de-fined on the basis of subjective judgments. Such a traditional design methods are difficult to quantify and lack the logical basis of describing uncertainty. Especially, reinforced walls consider not only soil properties but soil-reinforcement interaction uncertainties. There has been much emphasis recently the use of probabilistic method in the geotechnical engineering. The most effective applications of probabilistic methods are involv-ing relative probabilities of failure or illuminating the effects of uncertainties in the parameter. This thesis de-scribed how probabilistic description of soil parameters and soil-reinforcement interaction parameters were applied to the stability analysis. The first-order, second moment approach was explored and applied to the de-sign of reinforced retaining walls. An example illustrated the relative contribution of uncertainties about dif-ferent parameters to the reliability of the reinforced retaining walls. The results obtained from this study were follows; the reliability of the soil-reinforcement interface friction angle, δ was highly sensitive to the coeffi-cient of variation. However, when the reinforced fill unit weight γr, and the reinforcement length, L were lower than the limited values, the probabilities of failure were increased. The reliability of the retained back-fill soil unit weight, γf in the unreinforced area was lowly sensitive to the coefficient of variation.