Design and analysis tools for steel grid mechanically stabilized earth walls considering corrosion

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Technologies to improve the ground in civil engineering earthworks such as retaining walls are advancing**rapidly. As just one example, retaining walls constructed with horizontal layers of advanced polymeric soil**reinforcement sheets and steel products have been demonstrated to reduce the cost of conventional wall**solutions by up to 50% and provide more sustainable solutions in competition with older technologies. In North**American terminology these systems are called mechanically stabilized earth (MSE) walls. Currently the**Canadian geotechnical engineering community is migrating from methods of analysis and design that describe**margins of safety in terms of factors of safety to margins of safety described in terms of probabilities of failure**which include load and resistance factor design (LRFD). The latter is a more rigorous approach and brings**MSE wall design into alignment with structural engineering practice. Included in the MSE wall category are**systems composed of a concrete facing and backfill soil that is reinforced by layers of galvanized steel grids.**This is a technology provided coast to coast by Atlantic Industries Limited (AIL) in Canada. Current models**for stability of these systems against tensile rupture and pullout of steel grids in the reinforced soil backfill are**now two decades old and their accuracy using a database of recently collected measurements in the field has**not been fully examined. Furthermore, LRFD codes used in Canada and the USA produce different design**outcomes for the same steel grid type which can put some suppliers of steel soil reinforcement such as AIL at a**disadvantage. Coupled with this challenge is the lack of a rigorous and accurate approach to incorporate**potential corrosion of the steel reinforcement into lifetime predictions of the reliability of steel grid MSE walls.**The influence of steel corrosion on lifetime performance of MSE steel walls is often raised by designers. The**results of this collaborative research program with AIL will provide modern performance reliability-based**analysis and design tools for AIL including recommendations for minimum zinc (galvanic) coating. These will**assist AIL to promote the use of their steel grid MSE wall technology in Canada, the USA and internationally.