a stacked block wall, poorly installed

Post date: Nov 20, 2015 6:43:46 PM

Outlier designs a lot of retaining walls.  One of the popular requests is for stacked block limestone retaining walls.  Right away, I tell people that these are not gravity walls.  The limestone is heavy, yes, but after about 3 courses, it is not heavy enough.  Typical designs for this include several layers of geotextile that act the same way straps do on an MSE wall. 

Here's the pretty side of a recent project:

As always, we try to entertain and educate so that you can avoid mistakes.  So here's one of the mistakes caught during construction.  

You can see that there are some gray pipes installed behind the wall.  You may also see that the wall leans out just a bit.  There is a batter on the wall, so it is not in imminent danger of collapse, but ...

You can see that on the other side of the wall, there is a lot of erosion.  The installation of the pipes caused a low spot, which attracted water that then flowed along the outside of the pipe.  It didn't take long for the soil in front of the wall to get soft from the water in front and behind it. The sharp-eyed among you would notice the that the geotextile must have been cut, the slope in front of the wall is ridiculously steep and the water flowing under the block must have reduced the bearing/resistance to sliding.  

During the reconstruction, we had several conversations about these topics.

For this project, something else dictated that this portion of the wall had to be rebuilt, so I didn't have to break that news.  The next build was much better.