Is this retaining wall going to collapse soon?

[redhexagonal]

I have a 1.6m high retaining wall , 4m across, at the end of my garden, made of 2.6m x 125mm x 250mm sleepers which may be pressure treated or reclaimed , wedged into steel I-beams. They are layed directly onto the soil and soil and rubble behind the wall is directly in contact with it, no membrane. There are inch wide drainage holes every 80cm or so .
I had a look at the face of the wall which faces my neighbours garden, and there was a lot of rot, and one of the beams seems to have cracked in the middle and moved about 15mm. The beams are also a bit short for the I beams and are wedged in with bits of wood, also rotting.
Is this likely to collapse catastrophically ?Because I’d like to make a garden up top but I don’t want it to collapse into my neighbours garden.
Not sure what to do.

Last 2 pics are from my side up top, rest are from neighbours side

 

[freddiemercurystwin]

I expect it will continue to break down slowly and the sleepers will split/fail individually rather than the whole wall failing catastrophically but I wouldn't have my kids playing near it, its certainly a potential killer if it were to fail catastrophically. If the steels are still OK then replacement sleepers would seem to be the obvious repair.

 

[scbk]

They are genuine sleepers, you can see the marks where the plates were fitted

 

[conny]

They need replacing before you make your garden on top.
I put down a freshly cut 9" diameter log in one of my flower beds about 3 years ago as a bit of a feature. Throughout the past years I've often stood on it to tie up/prune some climbing roses. On Friday I stepped on it and it simply crumbled to dust in the middle, yet it looked as firm as it has done since installation.
Your set up will collapse, of that there is no doubt. It's how it may collapse that is the unknown. It may suddenly go catastrophically, or it may crumble and create a landslide effect. Either way could be very dangerous if there is someone in the area when it does go.

 

[redhexagonal]

They need replacing before you make your garden on top.
I put down a freshly cut 9" diameter log in one of my flower beds about 3 years ago as a bit of a feature. Throughout the past years I've often stood on it to tie up/prune some climbing roses. On Friday I stepped on it and it simply crumbled to dust in the middle, yet it looked as firm as it has done since installation.
Your set up will collapse, of that there is no doubt. It's how it may collapse that is the unknown. It may suddenly go catastrophically, or it may crumble and create a landslide effect. Either way could be very dangerous if there is someone in the area when it does go.

They’ve only been there since 2015! any tips for how to make a longer lasting retaining wall? I imagine there needs to be a membrane or some drainage between wall and ground?

 

[conny]

You could either use sleepers again, but would need to put some waterproof barrier between the sleepers and soil, or possible use concrete beams for the sections that will be in contact with the soil. Some largish pebbles at the base, covered with some weed control matting that allows water through but not soil/detritus, could help drainage.

Have a look at this, (and similar sites), to get an idea of what's required.

Retaining Wall Drainage & Backfill Basics - Landscaping Network

Discover four retaining wall design basics – base, backfill, drainage & height – that will help ensure you get a quality wall when hiring a landscaping contractor.

www.landscapingnetwork.com

 

[Mike13]

but some dpc sheet behind the replacement sleepers so that they spend more time dry, and gravel/pebbles behind that so that water always gets to the bottom.