An integrated limiting equilibrium approach for design of reinforced soil retaining structures: Part Ⅲ—optimal design

摘要

Classical retaining structures and conventional reinforced soil designs are limiting points of a continuous spectrum of potential solutions. These limiting cases represent legitimate designs, but they are not necessarily optimal. The present work considers the issue of optimal design of reinforced soil retaining structures in this spectrum. For the particular example considered in the present study the cost of the optimal solution is 47% of the cost of classical cantilever wall without soil reinforcement and 65% of the cost of the conventional reinforced soil design which neglects the wall contribution during reinforcement design. These values depend, naturally, on the support problem under consideration, and component's unit prices, but they clearly illustrate the large potential benefit of the proposed design process. Conventional design procedures do not have the tools needed in order to evaluate interaction between the wall and the supporting system. As a result, conventional design procedures are restricted to the two end points of the spectrum of potential designs, in which one or the other of the two main components of the support system (wall, or reinforced soil) is practically neglected. The design procedure presented by Baker and Klein (Geotext. Geomembranes 22 (3) (2003a) 119-150; Geotext. Geomembranes 22 (3) (2003b) 151-177) overcomes the limitation of the classical design approach by the introduction of participation factors which quantify the interaction between the wall and the reinforced soil. As a result, the proposed design procedure allows one to quantify the economic trade-off between different walls and supporting systems, making it possible to consider optimal design issues.