The gap is what is annoying/concerning however.

If you put dirt in there, will the pillars be strong enough to push through it,

(it will) but will it also be affected by the moisture/critters inside the soil?

 

Also, if water, that is damage on the pillars + people would need to jump over it,

or needs a small bridge that robotically separates in two from one side to another,

leaving space for the pillars to later push out.

 

OR,

you can generally try to create a stepping panel over it, but it must not affect

the gaps between the pillars side to side, so it must kind of 'hover' from

the one end without support of the ground from one end.

But that is not so difficult if using triangular support, like you see in

wall installation bookshelf units. Just an arch.

If against the weight of pedestrians walking on it that is.

For vehicles, it will require a bridge.

 

 

OR. You could install another concrete pillar in front of the ceramic pillars,
to prevent the soil from contacting the ceramic. Leaving only a tiny gap.

And just cover the rest of the area with dirt.

 

Your choice. I'm just suggesting options.

 

 

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Ok. Now tried perfecting how the pillars.

Drew it in sketchup. Download:

 

1. Create the frame with a metal base, that must hold the gear tracks.

2. Drop in the ceramic shell to that metal frame.

3. And pour in some cement to bind them together.

 

 

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Lastly, solved the 'gap' issue.

On thinking, I don't think there needs to be a gap.

There can simply be a divider.

Between the pillar and the dirt.

So nothing collapses below the pillar when it protrudes.

After that you can just cover the rest with dirt as nothing else is moving.

Drawn in Sketchup, download: