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Retaining wall + biaxial geogrid

Retaining wall + biaxial geogrid

Retaining wall + biaxial geogrid

Hello all,

New member here. I can pick up your experience in a design issue I am facing.

I am designing a retaining wall using Lock-Block concrete blocks. The wall height changes through the alignment, between 2 m (6.5 ft) to 4 m (13 ft). My preliminary design was using Stratagrid uniaxial geogrids (SGU 100 kN/m - 6852 lb/ft), but the client wants to use biaxial. There will be muck cars and loci (98 metric tons - 216000 lb), and a TBM gantry (23 metric tons - 50700 lb) near the wall. The closest proximity is for the loci and it is 2.5 m (8.2 ft) away from the wall, where the wall height is the same. So, the concern is the live loads during the operation. I must say that these loads are not permanent since the tunnel advance will make them go away.

I tried to find a biaxial geogrid with the similar tensile strength but the max I could find was 40 kN/m (2740 lb/ft). Also, I could find data sheets with LTDS, reduction factors (chemical, installation etc), for the uniaxial ones, but not for the biaxial. I am starting to think that no one is using biaxial for the retaining walls. I am not really experienced in retaining wall and soil reinforcement, so I appreciate if you can direct me in the correct way. Also, is there some sort of conversion that I can use to find out the equivalent required biaxial tensile strength?

RE: Retaining wall + biaxial geogrid

The loadings, live (construction or otherwise) and dead are the loads, regardless of which grid you use.

If a biaxial grid works with the appropriate loads then use it as it is cheaper.

If it doesnt work then tell the client.

You should be trying to accommodate the client.

RE: Retaining wall + biaxial geogrid

In my experience, the only biaxial geogrid manufactured are the lowest strength in each manufacturer's line. I have never been able to make the biaxial grids work for anything but walls a few feet tall.

As i was typing, i remembered one manufacturer who does make some higher strength biaxial grids but not sure if it will work for you. The product is Gator Grid. I had one job where the installer used it, and I wasn't too impressed with the product in the field. It's been a while, but it physically seemed different that other grids I am used to. More stiff and plasticky.

I don't think Gator Grids make something equivalent to SGU 100, but might be worth looking into.

RE: Retaining wall + biaxial geogrid

Thank you for the responses.

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