DIY wooden sleeper retaining wall advice needed

[Zeffo77]

Hi.
I'm hoping someone can offer some assistance please.
I have a front driveway which is approx 14m x 14m.
It is currently on a slope and I am planning to build a retaining wall with oak sleepers.
The wall will be 1.1m high and will be 2 tiered, like steps.
I am going to have 2 trenches for each wall with a horizontal sleeper used as posts in concrete behind each wall.
In the trench will be DPC material and then some form of aggregate with then concrete added to make a flat base.
I want to sit the sleepers on their narrowest side, 100mm.

I will connect the sleepers with wooden dowels for extra strength.

To reinforce the walls, I will run deadmen/t-bar reinforcements every 8ft along every row and every other row in height.

I will also be laying a French drain behind both walls leading to a dry well at either end of the wall.
I have attached images of a very rough diagram to illustrate this with also my driveway currently and how i want the wall to look like.
My questions are:

1. How deep should my trenches be and how much of the 1st sleeper should be below ground level?

2. How should I attach the 1st row of sleepers to the base? Rebar or coaches or something else?

3. Can I feed the perforated drain pipe around the horizontal posts? Will that not affect water flow?

4. Is having the 2nd wall 6 sleepers high too much? Will it be secure with the deadmen/ t-bar reinforcements?

5. Should I be connecting the sleeper rows with wooden dowels or perhaps rebar instead?

6. Would corner metal brackets add to reinforce or are overkill?
Also, please feel free to offer me any guidance, or let me know I'm on the right track(!).

I hope the above makes sense!

[Mr Punter]

I have done sleeper retaining walls with C and I section (PFC and UC) structural steel and sleepers slotted between.  No trench needed.  Sink the steel at least 750mm in the ground and concrete in.  Use some terram or similar membrane on the back of the sleepers.

 

[Temp]

https://www.railwaysleepers.com/blog/tips-advice/how-to-build-a-retaining-wall-with-railway-sleepers

 

[CC45]

we've got a retaining wall thats 4 sleepers on their sides deep at the worst point - fence panel on top of it.  We dropped some RSJ's in (concrete) 1m+ working an a 1/3 in the ground.  Slide sleepers down them.  Get someone to bore the holes for you - look up agricultural fencers in your area - they frequently bore holes so should have the kit.  They are quick at it and well worth the cost.

[Onoff]

21 minutes ago, CC45 said:

we've got a retaining wall thats 4 sleepers on their sides deep at the worst point - fence panel on top of it.  We dropped some RSJ's in (concrete) 1m+ working an a 1/3 in the ground.  Slide sleepers down them.  Get someone to bore the holes for you - look up agricultural fencers in your area - they frequently bore holes so should have the kit.  They are quick at it and well worth the cost.

 

Were your steels galvanised or just painted?

[CC45]

just painted with red oxide and then a bitumen coat on top out of the ground.  They were hefty beasts - will see me out for sure.  Cheaper tha putting a block wall up.