Photo Credit: Karl Jansen
Pictured here is a retaining wall constructed using steel. A retaining wall is used when there is a large elevation difference in a short horizontal distance. In this case, the pond on the left of the photo is much lower than the parking area on the right of the photo. Retaining walls hold back the earth for the higher land to remain stable from erosion.
Photo Credit: Alex Mead
This is a soldier pile and railroad tie retaining wall. These types of walls are common due to their relative ease of construction and the availability of materials. Simply place the vertical members, brown tubes in this case, and stack the railroad ties behind. Then, back fill can be placed behind the wall. One major problem with this wall, however, is the placing of the railroad ties. All joins should be staggered by many inches and secured with large spikes. As you can see on the far right this is not done, and greatly reduces the strength of the wall.
Photo Credit: Alex Mead
Seen here is the failure of an auger cast pile wall. This type of wall is designed to be a watertight retaining structure for the construction of an underground project. Although it is hard to tell from this photo, the wall appears to have failed due to weak concrete in the piles. One pile broke and released the material it was suppose to keep out of the excavation. This failure formed the mound of dirt seen in the photograph and a “sink hole” approximately 20 ft by 10 ft by 30 ft deep behind the green fence screen. This is what a bad day looks like for a geotechnical engineer.