Gorund Uplift/Improvement by Resin Injection ?

If you are looking to raise a foundation or slab then resin injection can work.

However if you are looking to improve the ground (with no foundation above) by grouting then you can ignore the improvement in the upper few m or so.

Displacement grouting requires a reaction to expand against in order to densify the soil. In the upper few meters the overburden stress is too low. The grout just causes the ground to heave and there is no improvement. If you have a foundation then it gets its reaction from this, eventually when you pump enough you can raise a settled foundation.

We did this a few times in New Zealand on buildings that had settled. There is no "design" as such its based on empirical knowledge with the contractor taking all the responsibility. They essentially drill holes at a certain spacing then start pumping incrementally. drill holes added as needed. Its crude (but so is most ground improvement methods) but I have seen it re level foundations that had settled over 200mm!

Regarding long term aspects, its a cement based resin that you are using. As long as you include the right additives to combat any aggressive ground then design life is as good as any other solution .

Thanks, EireChch..

Just one clarification - You mentioned Cement based resin - The one I have spoken to uses a two-component Rigid Polyurethane Foam System. Namely Polyol and Isocyanate. Inert materials hence I don't see an issue with long-term issues however I did ask for any accelerated creep test they have performed - yet to receive any info.

It is all empirical - so I am a bit cautioned about how we get involved as an engineer and what can we certify whilst safeguarding my organization's interest.

I was on-site start of the week where they were injecting the Resin - Your point makes sense as the foam that leaks out of the ground was soft as it condensed without overburden pressure.

It was a residential slab - but amazing that they lifted the corner 98mm.. see the attachment -