Retaining wall + biaxial geogrid

[hkumas]

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?

 

[EireChch]

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.

 

[Jrit]

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.

 

[hkumas]

Thank you for the responses.