Embankment on fat clay. What helps?

[Mickyluv]

I search through these forums a bit when I'm looking for ideas and you guys have some amazing solutions, so I thought I'd throw this question at you. I have this 20ft high embankment with 3:1 slopes built with fat clay (PI average 45). Over the years, the road surface has needed a lot of repair, probably due to shrink and swell. The site gets very dry in the summer and wet in the winter. I have been advised to utilize lime treatment on the slopes to keep the moisture level more constant within the embankment. Does anyone have experience with this working? I'm concerned that the exposed lime treated soil may crack or the lime eventually become ineffective. Are there better alternatives (i.e. line the banks with a geomembrane)? Thank you

 

[GeoPaveTraffic]

I share your concerns about using lime treatment on the side slopes. However, you could place a layer of lime treated soil beneath the roadway to reduce the amount of shrink swell directly effecting the road bed.

Have you verified that the damage is in fact being caused by shrink/swell? I would make sure that you are fixing the correct problem before taking action. It should be easy to tell by taking some water content samples below the road several times during one year and seeing how they change. You could also do several surveys to verify that the road is going up and down.

 

[BigH]

GeoPaveTraffic gave some good comments. As for other causes - you need to rule them out. If built out of fat clay, perhaps there has been a consolidation effect over the years due to self weight (of the embankment within itself) - possibly, there is still foundation settlement that would cause uneveness in the road surface.

 

[Mickyluv]

Thank you for the responses. The embankment was constructed about 50 years ago, so I believe most of the settlement has occured other than maybe a little bit of creep. Are there any other alternatives I should consider that have been used for situations such as this? The only other thing I can think of is remove and replace.