Analysis of Costs and Choice on Retaining Structures: Land, Curtain Wall and Slope

The objectives of this work are an analysis of the costs about the retaining structures and one model that permits the choice between the design of a retaining wall or a slope. The main goal is to build graphs and to develop a computing tool facilitating the determination of the costs and the optimised choice. This approach supposes that the safety coefficients of the structures have same value and that the drainage is well made.

The lack of space in the urban zones requires an optimised solution regarding the functional, security, economic and aesthetic points. The standard cantilever wall is composed of a vertical wall having a variable section and of an interdependent sole with the wall. The slope is represented by a height (H), and a width (L) in accordance with the relation L = H/tgφ, where φ indicates the angle of natural repose.

The volumes of the retaining wall and the equivalent slope which can replace the wall are evaluated at first. After having evaluated the necessary land space to the influence of the slope, the realisation cost of the retaining wall is compared with the cost of realisation of the slope and the cost of the surface of the lost land. At last the work finish by the presentation of the computerised program and the graphs illustrating the costs and the optimised solution.