Sleeper planter advice needed

Hey all.
I’m looking for some advice on a sleeper planter I’m looking to build soon.
I am intending on building a 3 tiered planter made from 2.4 x 200 x 100 sleepers. The height will be 600mm and the length 3400mm and the depth 1000mm
I will have a dip 2/3 along for a hose reel and tap to be set in, but you don’t need to know that much detail.
I am looking for advice on whether or not you think I need to set steel reinforcing bars into the concrete pad and up into the bottom tier of sleepers to anchor the planter and stop it moving over time?
My main worry is that as it will be holding a few tonnes of soil, there will be a lot of pressure on the sleepers, pushing outward, especially the bottom layer.
Does anyone have any advice?
P.s I plan on using heavy duty 90 degree galvanised steel corner brackets on the inside to join the sleepers and probably an inner frame made of 3x2 timber to lock it all together.
Thanks in advance!

 

I'm partway through a similar project! It got put on hold last year while I focussed on other things, but it's back at the top of the list now.

I'm certainly planning on doing that. With the sleepers on their short side, they aren't going to be as stable. If you're using oak sleepers, you'll need to use stainless bars - the tannins in oak cause normal steel to rust away.

My plan is to use lap joints where the sleepers meet. I'm going to use threaded rod set into the concrete, so that'll give me my reinforcing and hold the structure together, without needing extra brackets or framework. Then tighten a nut down on the top (recessed, of course) to hold it all together.

At the moment this is still theoretical! It's the top project on my list now though, so I'll be cracking on with it pretty soon.

 

I drilled my sleepers (no mean feat - cumulatively they are pretty thick) and stuck Rebar down the holes and banged it a long way into the ground beneath. My sleepers have still "lent over" and "bowed out" quite a bit, albeit that I don't think there is any risk that they are actually going to wander.

Concrete footings for the Rebar would have probably helped.

 

Kristen, that's my reason for planning to put in some decent footings. Lap joints at the corners should also tend to hold everything together, I hope, so the structure generally keeps itself together. We'll see whether it follows the theory!