Formwork wall with or without foundation

Hi guys!
I'm a bit desperate...
I have to start a slope towards the neighboring property, from the street 0mm to the end of the terrace 120mm. I'm here chipping away with a pickaxe, the ground consists of stone bound with clay.

I'm already pretty deep below the natural ground level, do I still have to go 80cm deep because of frost safety?

Ideally, I would now excavate a little bit, embed vertical reinforcement in concrete, and then start with the wall.

Hello M4rvin

120mm or 120cm?
You have to support the left slope?!
Is what you see in the pictures the excavation?
Even if you don’t consider the frost line, what is supposed to resist the pressure from the earth on the left?
You can’t drive rebar into the clay soil. It would rust away.
Think of it like bodybuilding, dig 80cm deep. I might even widen the foundation to the right in the shape of an L (like L-blocks). If in a year or two the support tilts to the right, you can start all over again.

Steven

Oh dear, yes I meant 120cm! You can't really see it well in the pictures, only the piles I have already cleared away... It hasn't been properly excavated yet, at the moment I'm trying to level everything a bit. The slope holds on its own, it's actually like a wall! (Through the vein of stone) Excavating 80cm is really impossible, I would need 40 weekends for that! Next to the wall, there will be a garden shed, could I "connect" the foundations?

The wall will only be backfilled with soil on one side? Then you have to dig 80 cm deep to be really frost-proof. Or you take the risk and rebuild the wall in X years. How many meters long should the wall be? Rent a mini excavator for a day. It doesn't cost the earth.

Exactly, I will refill the neighboring side again. However, it is possible that they will also change something on the terrain when they start with their house.

Ok, so 80cm deep from the top of the planned surface? (It will be paved, about 50cm has already been excavated and filled with mineral concrete, but not at the boundary where the wall is supposed to stand)

There is a bit of a lack of space for an excavator there, the heat pump, stones for the terrace wall, and the packaged garden house are standing there.

The wall will be about 8m at first, because with 8m I am at about 40cm height. The boundary length is about 16m.
Approximate gradation:
1.2m at the beginning
1.0m after 2m
0.9m after 4m
0.6m after 6m
0.4m after 8m

80cm excavation is really impossible, I would need 40 weekends for that!

Excavator takes one weekend and costs 150 euros.