Berm Design

[GeoGrouting]

We want to make a 1 m high berm near a ditch to prevent the potential floods entering our camp side. They have suggested a berm that has 1 m width at crown and 4 m width at the base.

I guess one of the tasks is to check the slope stability (which is unlikely to fail. What other design parameters and procedures should we use for the berm.

 

[dicksewerrat]

Build a clay center for the berm. Normally clay is not a good foundation for bldgs, so it will be easier to get.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[ACtrafficengr]

How will you get the water out of your side of the berm?

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

 

[cvg]

check for erosion and freeboard.
you are suggesting 1.5H:1V side slopes which is very steep. slope stability will be a problem at this steep slope. 2.5H or 3H:1V is generally recommended as a minimum stable slope for most levees and channels. Unless you have a long period of flow or ponding water or the flooding risk is very high, then importing and building a clay core is probably overkill.

 

[msquared48]

Should be more like 3:1 was my thought too...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[GeoGrouting]

The client wants to make the berm with 1.5:1 slope because of space limitation. The berm thus would have 1 m width in the top and 4.5 m width in the contact zone with the ground. How does this relatively sharp slope affect the choice of materials compacted. Do we need to compact to a certain density.

 

[cvg]

regardless of what material you use, you should compact to reduce settlement, increase in-place density, reduce infiltration, increase the stability of the embankment, reduce erosion, etc. Again, 1.5:1 is not recommended and will probably not be stable long term (regardless of what type of soil you use). I would recommend concrete slope protection

 

[csd72]

You should also check overall sliding and overturning (though unlikely) and check for the possibility of water filtering through underneath the dam.

 

[GeoGrouting]

Thank you for the feedbacks. Unfortunately there is limited space and a slope of 3:1 cannot be made. A slope of 3:1 requires 7 m at the base and I have only 6.7 m even if the toe of the slope is at the margin of water in the ditch. What would be the design implications if a slope of 1.5:1 should be maintained?.

 

[cvg]

the implication is that an earth embankment this steep will fail within short order, you need to use a structural alternative such as concrete or plan on frequent maintenance

 

[GeoGrouting]

How about having a slope of 2.85:1. In that case the toe of slope would be almost at the edge of water. If so should a rip-rap be placed at the upsteam? or should I go for a concrete retaining structure?

 

[cvg]

you need to evaluate the hydraulics and scour with respect to the amount of flow, velocity and soil types to determine if erosion protection is necessary.

 

[fattdad]

Put some geogrid/textile in there and make the slopes 1:1 if you need to.

f-d

¡papá gordo ain’t no madre flaca!

 

[BigH]

Unless the lack of sleep has affected me, how many 1 m high berms has anyone seen fail? even at 1H:1V angles (assuming "clayey earth"). The problem may arise as the to stability of the channel above which the berm will sit - it is doubtful that 1 m surcharge will dramatically affect the channel wall stability but, depending on geometry, etc., it might want to be considered.