need help with access road across steep slope

[Sodo]

And not even a driveway, just a spur. I already bought the geogrid. Is "3ft rise over 6 foot run" called a 2:1 slope? That's the slope of my engineered fill, much more 'relaxed' than the geogrid diagram I posted. It's appx the slope that the rock would hold at even with no geogrid reinforcement. I can't find any diagrams with the slope I'm using, I assumed because nobody would waste geogrid on such a 'gentle layup'. I'm being conservative (I think ?? ) using the materials I have access to.
Seeing as I seem to have some real knowledge replying ( :cool2: )
,,,,,I will try to post more pics.

Glacial till passes everything it can get, but will scour if there's flowing water. Good reminder about the drainage as the compacted gravel surface from the driveway above will shed water onto this access. I will have to channel that away from the project until I figure out a reliable way to deal with it. I can keep ontop of it as it 'adusts', will re-fill settling, and deal with the water. I'm interested and understand water effects pretty well, but there's always more to learn too.

Really appreciate the help.

 

[Sebculb]

Most little private driveways aren’t engineered. It’s quite typical to cut/fill while making a driveway and simply use the machine to compact in 6-12” lifts. Rip Rap helps with water erosion but isn’t really designed for retaining soil much above 4”.

My biggest concern with a road is the drainage. If that isn’t right (crown culverts etc) you can kiss a lot of your work goodbye when it rains. With regards to compaction- yes things will settle and move. Unless you plan to bring in some heavy equipment, possibly import material depending on soil type and have testing done odds are it will move. Movement is ok and normal as the road get compacted over time and with use. Simply add material as it settles.
Everyone has a different expectation of what geo fabric is. Wit a 2:1 slope I don’t think I’d put it on the slope unless their was a water issue I was trying to solve- see rip rap above. The place to use the fabric is on the road- lay the fabric and then use 4-6” of road base on top to finish out the road.

The photos look like you are doing a good job and your level of concern is more than most. I’m sure it will be fine.

I like to cant it in exaggeratedly to the upslope side and dig a ditch or have one magically form in the corner between the road and dirt wall. Then run it down to a convenient place to run a culvert underneath the road do get rid of the water or whatever works. I try to keep any water from washing down the fill side because a little water can cause gorges and wash away a lot of useful fill quickly. And if the canted angle towards the wall seems seems steep, it usually compacts down in a little while and that way the water is guaranteed to go where it should.

That terrain looks pretty flat compared to what we deal with around here! Like What RNeumann said, Im sure it´ll be fine. Good luck!

 

[Sodo]

Yeah I'll watch the water, and make sure it's not running over the fill side. I am assuming that the geogrid rubble support below will be like a large drywell under the road, and the water will infiltrate down to that area and disperse slowly. This is a hilltop and other than the (gravel) driveway surface above there is no other source of water.

Here's today's pics. It's raining, and just mud. There's a thin layer of soil over the first course of rubble. Today in the rain I can start assembling the first geogrid layup.

I sure would like to cover each layer (of rubble) with 1 1/2" crushed rock but I don't want to spend any more money on it until I get nearer to the top courses & final gravel. You can see a 10y pile of covered (sandy) soil to the left of the eqpt. It's more than 50% sand.

 

[Sodo]

Started my layup today. There's one course of rubble, with dirt, so I could drive the excavator over it one more time. The first layer of geogrid is ontop of the layer of dirt ontop of one course of rubble.

The plan is (or was?) to go up 3 layers of rubble and wrap the geogrid back over the roadway. 3 layers is about 15 inches, so I'd have to do this 3 times. It was time-consuming to stack the little "wall" then lay in the rubble behind it minimizing the voids.

The railroad tie is just a "fence" to prevent rubble tumbling off the pile from going over the edge.

Then I watched this YouTube. Which has convinced me that I'm being a little too **** (and consequently, slow). The Geotextile is going to do what I need, without so much careful stacking. Maybe I'll just finish out the good solid base then just pile up layers fast.

If not interested in the engineering mumbo-jumbo skip to the middle where he shows some simple tests.

 

[Streetcar]

Sodo
Did not watch video, but the sand is small grain and can uniformly load the geogrid.
Is there any markings on geogrid. They can vary greatly in strength.
For similar example that most will understand. A half ton pickup looks similar to one ton but has greatly different capacities

 

[Sodo]

I didn't see any marking, and haven't looked. But it has to be somewhere; for the inspector to sign off on, and what if he/she can only see the middle? I got it from a contractor who was building Taco Bell parking lots (level I suppose). I bought 300 feet, so I'm pretty much stuck with it for awhile. He quit because he started flipping houses (in the Pac NW) which paid better and now's the time to make hay. But the parking lots had to be stable for many years and for big trucks. I have never handled Geogrid before, so can't know if it's thick or thin but I'd call thick & ornery. It looks exactly like the pic I posted (from the internet).

It's the level stairsteps that do it, and the geogrid lets you go (towards) vertical on the stairsteps. And I'm not going vertical, I'm keeping almost with the angle of repose for rubble, so there's not much stress. In any case I've seen a lot of road cuts in the mountains using no geogrid at all. I have to backfill the rubble to drive the mini-ex on it, but probably will fall thru over time. Agreed this is not a good roadway for cement trucks - it's a deadend to a small roof structure. Being next to the driveway it's obviously cut into disturbed soil (from 60 years ago).

This is great, I have gained some useful understanding. And happy that I can move faster today too:thumbsup:. Will look for a marking so I can at least learn that part of it.

 

[dragoneggs]

I thought the video Sodo posted is an excellent tutorial on how geogrid works explained to the layman. :thumbsup:

 

[Sodo]

Yeah that Youtube gave me high confidence that this will work.

Will look for a marking so I can at least learn that part of it.

No markings whatsoever on the Geogrid. It's molded (not woven) and is about 1/16" thick.

It rained hard last night and into the morning, including snow. I had to wait until the afternoon to work at all, and spread some dry dirt from a covered pile to be able to drive the tractor at all. The truck came with my free rubble, and had about 100 gallons of water in the dump bed. Which was very disappointing cuz it dumped right in the middle of the action.

Here's the status as of 6PM today. Almost ready to roll the geogrid back over the shelf. Im up 24 inches over almost 30 feet of the first course. I stack a wall with the biggest chunks then just backfill it with smaller rubble. This thing is frickin' HEAVY, there's no way that Geogrid's gonna move ever.

I stopped the tractor and lifted the bucket for the pic. So y'all could pucker with me....;.

 

[dragoneggs]

that last pic clarifies what you are up against. Looking good.

 

[rockingclawhammer]

Quite a project you have going. We have a steep crossing, but we are going straight across. I used concrete rip rap in the bottom and got it pressed into the soft soil until I had a firm base. Then put in 4 each 30" x 10' pieces of pipe in the bottom. Then used more rip rap to build a road base over the pipe and to fill the voids between the 2 high points on each side. This crossing is subject to flooding several times per year. I started pouring concrete on the rip rap to hold it in place, so far I have only had 1 spot dislodge in a flood. I will be building that up again but it is still cross able. The last 2 years we have an 18 wheeler crossing it to access the back side of property where they are harvesting Mesquite trees. I think once that is done, the crossing will holdup better. I use dirt to top the rip rap for a smoother surface to cross on. I doubt this will help you any but thought it might give an different view that might work into your project.