Geogrid Holding A Car or How Does Geogrid Work?

[NewarkNation]

When I worked at Lame-gan, the Geogrid rep demonstrated the box of rocks and even recommended his product to be used as a fence.

[Danicorona32]

I never saw it like that. I work for Drill Tech Drilling and we do all types of retaining walls but never any walls with geogrid.

[locsman]

cool.

[slkhlaw]

I am studying a proposal of using geogrids and retaining wall on an approach embankment for very high speed train. The train needs to run on concrete slab track. The settlement limit is 5mm. I understand that geogrid will only work when it is stretched. So far I have seen literacture quoting 1.5% strain. Suppose I have a piece of string 1015mm long (geogrid) tied to both end of a 1m ruler (both sides of retaining wall), the sagging that I get in the middle is quite massive.

[RetainingWallExpert]

@slkhlaw The vertical settlement caused by stretching will be nearly immediate. There is very little evidence of long-term creep in granular soils. There are many projects around the world where reinforced soils support mass transit railroads. Vibrations and dynamic behavior (simulating seismic) should be analyzed. You could use metal reinforcement, which will give you essentially ZERO strain.

[cchanderson]

@slkhlaw One thing they are not demonstrating is vibration. Which is essentially its only weakness. This is why they always tell you to vibrate the hell out of the unconsolidated soil and rock before during and after installation. Your controlling the vibration with a downward force. Nature and trains for that mater don't transmit vibration in a controlled direction. Therefore using unconsolidated material and matting to stay within a 5mm tolerance would probably fail in that application.

[slkhlaw]

I have limited experience in dealing with geogrids which is why I am watching your video. I always have the impression that geogrids require substantial tensile strain before it will start to work. If my wall needs to move substantially before the geogrid would start to work, I would be concerned about the settlement behind the wall, i.e. settlement that may affect other people's property. Are you able to speak from your past experience what sort of magnitude your wall has moved?

[RetainingWallExpert]

@slkhlaw Using a sand or gravel soil there should be no noticeable outward deflection of the wall. There is always some, with every type of retaining wall, due to Active Earth Pressure, which is a fancy way of saying that we design the walls to "give" a little so that the soil's strength can be used. Vertical settlement should never occur. If it does, the the soil was not compacted properly.  Basically, simply pulling the grids tight during construction should be sufficient.

[hkki49]

great video.  Shows the uses of geogrids simply.

geosyntheticsworld com

[DameEdithDivine]

Very interesting, who would have thunk!