What kind of rock - how smooth or rough? The devil is in the details - and you didn't give the H:V angle for the rock face (in soils we typically use H:V - I am not sure if your "soil slope angle" is 1H:1.5V or 1.5H:1V??). The latter might be stable without reinforcement but the former wouldn't be.
In looking at the site, my first thoughts would be:
1. You should have a key at the toe of the starter - say cut into the rock face 4 to 5 m horizontal or slightly downward going into the slope - this will give you a solid "base" onto which to put the embankment fill. I certainly wouldn't want your slope to be sitting on such an acute angle to the rock face.
2. I would hope that your rock face isn't composed of thin layers all lining up parallel to the face. I saw an engineer decide to cut into such a slope to put in a small retainging wall for aesthetics - he had about 1000 m3 of rock come sliding down. You will need to map the jointing pattern of the rock to ensure that you don't have wedge pop-outs - not so critical when finished but might be when constructing.
2. Drainage, drainage, drainage. I would ensure that the "starter layer" is free draining - to keep the water away from the face of the embankment. You might even want to put in horizontal finger drains in the embankment draining back towards the rock face blanket drain (be sure to check filter requirements). You want to ensure that your fills are fully drained.
3. Not sure what you mean by "general fill". I have a strong aversion to using vernacular "loosy-goosy" terms for technical situations - I cringe when our designers put out drawings saying earth fill. Hell, that could be topsoil - it's earth!! You should be fully specific on the type of material you wish to use.
4. I am assuming that you mean 1.5H:1V - in this case you need, in my view, a well graded sand and gravel - glacial till would be okay. The outer zone needs to ensure erosion protection - this could be by a layer of larger stone (ensuring that the "general fill" doesn't wash through due to precipitation drainage. You do need to compact this material - do not get "lazy" with it.
5. The structural fill - again what do you mean by structural fill - I would presume it is like a road subbase. Again, proper compaction is essential.
6. If you do require 1H:1.5V - I think that you should go with a wrap around geotechnical reinforced fill as jdonville has suggested.
Nice graphic as far as it goes but really lacks details that can be essential. As indicated earlier, full descriptions would be so helpful (type of rock, jointing pattern, slickensides, geological setting (area of landslides????), more technical statement of fill types. Too, is this an area of seismicity? You can see what happened in Padang recently. Vancouver has a seismic acceleration of about 0.2g; here in Indonesia we are using 0.5 to 0.6g in some locations. Seismic can be very important.
As a young engineer, it is good that you are seeking advice - but, in my humble and "old" opinion - seek out geotechnical history. Devour articles and books by the founders of geotech - there are good engineering geology books (Krynine and Judd, for example although harkening back to 1957). Hutchinson wrote a state of the art paper on slopes to the 1969 Mexico ISSMFE conference. Read Terzaghi and Peck (2nd edition), Tschebotarioff, Tomlinson, Legget, anything by Bjerrum . . . Glean their experience and how they approach projects and situations.
![[cheers]](/data/assets/smilies/cheers.gif "[cheers] [cheers]")
and good luck with your career.
