| Have you ever admired a retaining wall in a | | | | this soil pushes down on the footer and basically |
| garden or near a highway and wondered, "Just | | | | keeps the retaining wall from tipping over. Of |
| how does that work?" Short walls slope | | | | course, the wall itself must be very strong as well |
| backwards but very tall walls are perfectly | | | | since the cantilever footing is only part of the |
| perpendicular to the ground. It can make a person | | | | equation. |
| very curious! | | | | The third type of wall, sheet piling, is often seen |
| There are basically three common types of | | | | around construction sites. You might have a seen |
| retaining walls: gravity wall, cantilever, and sheet | | | | large crane using a hammer device to pound |
| piling. The gravity wall is very common in | | | | sheets of steel into the ground to help in the |
| landscaping and is designed for short heights. | | | | construction of overpasses or highways. This is |
| Basically, the wall works by holding back the earth | | | | another brute force approach to retaining earth. |
| behind it by sheer mass. The wall simply uses its | | | | With a sheet piling wall, steel, wood or other |
| own weight to hold back the earth as the earth | | | | materials are driven into the earth up to |
| being held back lacks sufficient force to move the | | | | two-thirds their length. The remaining exposed |
| wall. Gravity walls need to be built in a roughly | | | | one-third is the part of the material the earth is |
| pyramid shape meaning that they get thicker | | | | pushing against once the wall is completed. |
| closer to their base. The thickness formula states | | | | Basically, the wall is anchored so deeply in the |
| that the wall's base needs to be one half to three | | | | earth that the soil pushing against it can't move it. |
| fourths its height. As a result, only short walls are | | | | If the wall is of sufficient height, tie backs are |
| practical and economical to build by this method. | | | | needed to keep the wall from bulging and |
| Building a 40' foot wall would require a base | | | | potentially failing. |
| thickness of 30'! Certainly, this is excessive when | | | | Further, all retaining walls need proper drainage |
| there are wall types that can be implemented | | | | behind them. If not properly drained, the resulting |
| with much less building material needed. | | | | hydrostatic forces will cause the wall to fail much |
| Such a wall is the cantilever wall as its the same | | | | quicker than it otherwise would. |
| thickness along its entire height. To hold it | | | | Next time you are admiring a well groomed lawn |
| stationary, a footing or plate that runs | | | | with an attractive rock retaining wall from a |
| perpendicular to the wall face is attached at the | | | | decorative landscape or hardscape, you will |
| bottom of the wall and extends back into the | | | | appreciate not only the aesthetic beauty but the |
| earth being retained. It makes the wall look like an | | | | elegance of the engineering in the wall's |
| upside "L". Once the earth is piled behind the wall, | | | | construction as well! |
| it will rest on top of the footer. This weight from | | | | |