Construction Cost Analysis of Retaining Walls

Retaining walls are relatively rigid walls used to support the ground laterally so that it can be held at different levels on both sides [1]. Retaining walls are considered all technical works, which allow the implementation of a sharp change in the level of the earth's surface, in such a way that the ground-construction system presents limited displacement or is marginally restrained. Support structures are mainly used in cases of disruption of soil continuity resulting from an excavation, below the natural surface of the ground, such as when building roads in a difficult geographical terrain with steep slopes. It is also common for them to be used in the construction of basements in urban areas, when there are other buildings or roads around the perimeter. In special cases, functional reasons impose the local elevation of the ground surface with grounding in the area around the construction, such as on bridge piers or in port projects, so it becomes necessary to support the soil mass. Finally, the construction of retaining walls becomes necessary to stabilize and protect natural slopes that present kinematic instability. The purpose of the present work is to compare the cost of constructing three retaining walls (gravity, cantilever, braced) subject to identical ground pressures. The retaining walls were designed using the same finite element software (GEO5), taking into account common parameters for the soil stress, the strength properties of the soil mass, the wall material as well as the diameter of the reinforcing steel bars, so that the results can be absolutely comparable. The market research that followed produced interesting conclusions on the comparison of the cost estimates for the three retaining walls.