What are the typical loads on a retaining wall?
In addition to the retained backfill, retaining walls may be subject to surcharge loads at the top of retained mass. A surcharge may be a strip load. The stem may also have concentrated loads at the top.
When the stem extends above backfill the retaining wall may be exposed to wind load. When retaining walls are located in seismic zones the seismic effects are considered by utilizing Mononobe-Okabe approach. ASDIP RETAIN is structural engineering software for engineering professionals to quickly model retaining wall loads. The image below depicts typical external loads on retaining wall.
Each applied load has a particular effect on the wall. The backfill exerts a triangular lateral pressure calculated per the corresponding earth pressure theory. The surcharge produces a uniform rectangular pressure on the wall. The seismic pressure is trapezoidal, with the higher pressure at the top.
For a more in-depth discussion of the theories and overall stability modes please read my post Cantilever Retaining Walls: An Overview of the Design Process (Part 1). The picture below shows schematically the lateral pressure diagrams on a typical retaining wall.