15m of 45degree Precast concrete wall on rock slope 1

[HH1969]

Hi,

I would like to seek advice or guideline on how to design a 15m wall (Precast concrete wall) at 45 degree angle. The rock surface is experiencing erosion problem, thus the wall is proposed as a surface protection method.
Appreciate if the members can share their experience on this matter.

TQ

 

[GabionGuy]

Going with a reinforced vegetated slope would probably be a more effective solution.

 

[dirtsqueezer]

The vegetated slope idea would be the the cheapest and most aesthetic solution. I believe you can order the handbook for free as well as this website:

http://www.ecy.wa.gov/programs/sea/pubs/93-30/index.html

Another would be shotcrete, more expensive and not so visually pleasing. As far as precast panels are concerned, there would be no way of compacting the backfill, as they would be at an angle.

 

[oldestguy]

Hi Guys:

After seeing the nuerous side hill slides in this mid-west area, I doubt that any soil type cover will stay on a rock surface in very wet weather.

I'd look at some form of paving using segmented blocks, rather than a solid inclinded concrete "wall". Of course it has to be anchored occasionaly since that whole thing may slide down also.

This is similar to what highway designers run into with the slopes of abutment area at highway overpasses. However, their slopes ar more like 2:1 or 1.5 : 1.

In any case look at what they do in your area.

 

[HH1969]

Dear Oldestguy,

I intent to use the precast concrete block with soil infill as the surface cover. My problem when doing the design is that, I am not sure what forces to be considered when calculating the safety factor, Sliding & Overturning.

There are:
W = mg acting downwards.
mg Sin 45 acting parallel to the surface,movement direction.
mg Cos 45 acting perpendicular to the surface, into the slope.

Then there is this reacting Normal Force with value mg Cos 45 but with direction perpendicular outwards from the slope. Then Friction. or internal friction?

Hope you can shade some light here. TQ.

 

[SEshore]

If your rock slope is stable and you are just protecting against erosion, you might consider applying a few inches of fiber reinforced shotcrete to the slope.

 

[oldestguy]

The sliding angle of friction of blocks on rock is something that is not likely sufficient for your job. Thus, anchoring periodically is needed, assuming you are not trying to hold it all up with the bottom blocks and using some inclined bearing resistance there.

I'd neglect any friction benefit and depend only on spaced anchors into the rock.

Is there any chance you can extoll the benefit of an exposed rock surface for appearance sake and forget the wall? Use the money elsewhere for some better benefit?