Vegetation is another possible cause of your embankment’s problems. Some homeowners actually plant trees or similarly large vegetation in the backfill soil that your wall is holding up. Filling that space might seem like a great landscaping decision at the moment, but after that tree has had 20 years to grow, its roots will start to push their way through your wall. And if that wall does fail, it will be bringing a tree crashing down with it, which is very bad news for any buildings in the vicinity.
It’s important to remind ourselves that this is a matter of physics and engineering, not brute force. It isn’t as simple as stacking a lot of large rocks together and hoping they hold. Even a small wall, relatively speaking, with only 8-12 inches of thickness, should be able to hold back a great deal of weight if engineered correctly. That can be accomplished with one of two retaining wall designs: gravity or cantilever. They have been the tried and tested methods of engineers for centuries.
Once you have the physics planned out, your next priority should be putting together a drainage plan. Unless you are planning on not having any rain, it is a necessity. A common solution is to drill weeping holes along the base of your wall. Make sure to also place material under the backfill soil that can filter out large particles and prevent clots. If your embankment needs a different solution, there are number of other drainage systems to choose from. It should also go without saying that any vegetation you plant in the backfill soil should be small.
If the backfill soil is already winning the war against your wall, there are a few steps that you can still take to turn the tides. There is no across-the-board answer for failing embankments. The answer for yours will depend on the specifics of your situation, and for that reason, this isn’t a do-it-yourself job. To ensure it’s done properly, contact a professional. They will be able to accurately identify the problem and prescribe a solution. To give your embankment more strength, they can add an anchor, drainage system, or, in some cases, can replace the material the wall is made of.