Retaining wall backfill question

[Aragorn84]

My garden is heavily sloped, and i have embarked on a project to create a flat "terrace" if you will.

To achieve this i'm planning to build a 1m high retaining wall along the bottom edge of the garden, then dig out some of the higher area and backfill in against the wall, giving a flat usable area of garden.

I've been looking at various plans for the wall, and i've got a little stuck on one of the details. General plan will be a concrete footing, probably around 700 wide, then a blockwork wall, 440mm thick at the base and then switching to 215mm thick a few courses up. The detail drawings suggest i want a ~200mm backfill of drainage gravel against the wall before coming along with the soil backfill, to avoid any hydraulic effects on the wall, which ofcourse makes sense.

I'm trying to get my head around the practicalities of installing the drainage gravel? Obviously the backfill itself will be easy enough with a small excavator, but can anyone give any tips or pointers as to how to sort this drainage gravel layer? Until the soil is in place theres nothing to hold the drainage gravel in place? we'd need some sort of seperator?

Google images visualisation of the end result (Sort of!):

 

[blup]

Stone in wire cages, (Gabions?)

 

[Aragorn84]

i mean sure, but thats a complete system in of itself right? you would do gabions instead of a wall.

I'm just trying to figure out how people backfill in against a wall like this with appropriate gravel.

Its a bit easier to figure if i'm digging into the high side of a slope as in that case, you simply dig out, and build the wall and pour the gravel in the gap. But in this case because i'm building at the low side, theres no gap, its all just open.

All i can envisage currently is some sort of "shuttering" like a sheet of plywood, and working slowly up in layers, lifting the board out each time

 

[freddiemercurystwin]

You would just do it as you go in layers. Add a layer of earth say 300mm deep leaving a gap between the earth and the back of the wall, then fill that with gravel, then repeat the process until you're at the top ....