Reliability based design of reinforced earth structures

The design methods currently used for earth reinforcement are mostly based on deterministic properties of both the soil and the construction materials used. This paper will tend to switch, out of necessity, to probabilistic formulations thereby modifying the existing design procedure of reinforced earth retaining walls to account for uncertainties and variabilities. Through a Taylor's series expansion about the mean, the mean and variance of the design parameters are derived in terms of the variations in the soil properties. Using appropriate probability distributions the overall wall reliability is assessed. The results indicate that in some cases, depending on the variabilities of the soil properties, a high safety factor may produce low reliability and thus unsafe design.