PDA

View Full Version : Proper Method of Geo-Grid Installation


GreenMonster
01-11-2006, 03:56 PM
Seems to me there is a little controversy, or maybe just a few different accepted methods for geo-grid installation. On a basic geogrid install, describe to me what the reinforced 4' behind your wall looks like.

cgland
01-12-2006, 12:05 AM
Mark - We have 1 foot of drainage aggregate and 5 foot of COMPACTED backfill. (Either fill soil or modified stone.) The backfill zone must be level with the top of the block so when you lay the grid down you don't have any fall-off behind the block. Your fill needs to be compacted extremely well, because if you have settlement and it pulls the grid you leave chance for failure. Obviously your grid needs to be installed in the correct direction too.
P.S. Drainage stone and backfill material are separated by geotextile fabric and slightly wraped at every pull.
Chris

UNISCAPER
01-12-2006, 09:25 PM
If someone cal walk me through how to post pictures here, I have several shots of grid going in, soil being compacted, burrito wrap on the drain, etc....

cgland
01-12-2006, 09:50 PM
Bill - Reply to thread, page down, click "manage attachments" browse your computer for pic, double click pic, hit upload, then post reply as usual.

Chris

UNISCAPER
01-13-2006, 10:30 PM
did that werk???

Squizzy246B
01-14-2006, 12:17 AM
did that werk???
Lol... No!...:waving: :) :)

cgland
01-14-2006, 11:10 AM
did you upload them?

chris

UNISCAPER
01-14-2006, 03:41 PM
Ok lets see here.....I hit the 'Browse' button, then doubkle click the file I want. Then hit upload. At that point the file should go to the screen in my reply for the post right? It's uploading and then does not go there.....

mbella
01-14-2006, 03:46 PM
Bill, it won't show up in the text box. It will show up under "Attach Files."

olderthandirt
01-14-2006, 04:26 PM
if the pics are to big it will also say that in the same box, as its trying to upload them. Watch that box as it shows the progress of the upload when its completed.

UNISCAPER
01-14-2006, 07:08 PM
I don't do this computer stuff well at all.... I'll go throught it again. I go to the bottom of the screen and hit the manage attachments button. Then a box comes up that says, "Manage Attachments". There are two field type boxes, one saying "Upload file from your computer, and the other saying upload from URL. On the upper box, the one that says "Manage attachments, next to it is a box saying "Upload".

Under these two boxes are a bunch of goofy things like avi, bmp, etc etc.

Just to let you know what place on the screen I am.... I click the "Browse" button, then a screen comes up with files and pictures. I double click a picture, and it's file name appears in the box right next to the "Browse" button. I then hit "Upload". I'm assuming atb this point the click link is suppoed to appear on the screen and it does not.

I have E-mailed these pictures before and the size thing was not an issue. They were also mailed to Keystone and they are doing a written Case study on the job. They said they would like to see the files bigger so they can use them for print.

Anywho, I'm lost:(:(:(

Dirty Water
01-14-2006, 07:30 PM
Bill, when you click upload wait for a minute or two and that window will change once it is done. Down where it shows the "avi bmp" stuff the file name will appear.

Once its done, click "close this window". Down where the "Manage Attachments" button is, you should now see the name of your picture file.

Squizzy246B
01-14-2006, 07:54 PM
I'll let Bill make the commentary (cause I wouldn't have a clue):)

Squizzy246B
01-14-2006, 07:56 PM
Sorry about the orientation:

Squizzy246B
01-14-2006, 08:01 PM
More to come

Squizzy246B
01-14-2006, 08:02 PM
This forum requires that you wait 45 seconds between posts. Please try again in 7 seconds. :confused: :dizzy: :blob1:

Squizzy246B
01-14-2006, 08:04 PM
.................................

Squizzy246B
01-14-2006, 08:05 PM
....................

UNISCAPER
01-14-2006, 08:06 PM
You can kind of tell that this guy's house was sliding down the mountainside. We were at 5,000 ft above sealevel, on rocky clay.

We had to dig 5' into the center of the slope and bury 7 full courses to meet aq 9'to daylight code writ. The bottom wall was buried uner a haul road we had to make to access the middle and top walls, then we peeled the dirt off and graded a 2-1 slope with the 257B. Trantual spiders were invading our jobsite, and those things can jump 5' in the wild. The redback diamond rattler also is home to this area. The total wall lift is 18', 6' of grid behind each course of wall. Keystone Century Wall interfaced on Standard units was the product. We have 120 tons of 3/4", and 45 tons of class 2 base, and the combination of our pad foot roller and Wacker got us 92-98% compaction.

Squizzy246B
01-14-2006, 08:10 PM
Here's a bunch more

Squizzy246B
01-14-2006, 08:12 PM
And some more

Squizzy246B
01-14-2006, 08:13 PM
Last couple for now:

mrusk
01-14-2006, 08:15 PM
Looks amazaing!

Squizzy246B
01-14-2006, 08:16 PM
........................Oh..there's another one...think my modem is going to melt:)

Squizzy246B
01-14-2006, 08:23 PM
I have some questions now Bill:

1. What exactly does Geo-Grid do??

2. I notice you use a vertical rammer rather than a platey for compacting the backfill..any particular reason?

3. In this type of work is the blade, rather than a bucket or 4 in 1 really an asset.?

4. What size Ex did you use to prep this site??

5....is not a question...thats a hell of a nice job.

UNISCAPER
01-14-2006, 08:35 PM
I have some questions now Bill:

1. What exactly does Geo-Grid do??

Strata GRid is a back tie system for segmental walls. You cut is as per engineers drawings, then compact 8" of soil at a time over grid, stopping at
24" for another soil hardness test. That has me worried about that other thread on this forum, the builder never indicated the soil was hardness tested.

2. I notice you use a vertical rammer rather than a platey for compacting the backfill..any particular reason?

Rammars are used in tight spots, the pad foot is used on big spots. You need a plate withint 3' of the wall face, as they don't reccomend heavy compaction equipment within that zone, you could bow the wall face.

3. In this type of work is the blade, rather than a bucket or 4 in 1 really an asset.?

The 6-1 blade is more an asset because of the tilt feature. The dozer tracks will ride where they ride, and since the loader arms are on tha same plane, idf you want particuular grade changes, you have to tilt the blade tips up or down, or left to right, as well as lift, drop of float. In this case, it worked great pushing material up and dragging it back down the face until the surface smoothed and packed out.

4. What size Ex did you use to prep this site??

On this site we rented a Bobcat 341. We had one 301.8 tied up on a job and did not have the new one yet. It worked well for what we needed to do with it.

5....is not a question...thats a hell of a nice job.

Thank you! It was 105°, 40 miles off shore, and dusty AS hell!

mbella
01-14-2006, 08:41 PM
So, Squizzy posted these pics for Bill? Is that correct?

I posted this before I saw Bill's last post.

Well, well, well, finally something Bill Schwab can't do.

Just kidding Bill. I've said it before and I'll say it again, you are definitely the most knowledgeable on this forum (except with computers). Great looking job.

Squizzy246B
01-14-2006, 08:43 PM
So, Squizzy posted these pics for Bill? Is that correct?

Nothing gets past you does it Mike:rolleyes: :cool:

mbella
01-14-2006, 08:51 PM
Nothing gets past you does it Mike:rolleyes: :cool:

A lot gets past me Squizzy. I'm guilty on not reading all of the posts. Give me a break:)

I didn't see your Johnny. That's what gave it away.

olderthandirt
01-14-2006, 08:55 PM
Nice work Bill, with the spiders, snakes and temp do you charge extra :laugh:

Squizzy246B
01-14-2006, 08:56 PM
A lot gets past me Squizzy. I'm guilty on not reading all of the posts. Give me a break:)

I didn't see your Johnny. That's what gave it away.

ROFL...Ok...my travelling costs for that job might have been a bit high but I'm sure Johnny would have jumped at the chance:)

mbella
01-14-2006, 09:00 PM
Johnny>>>> travel time!payup



Squizzy>>>>:cry: :cry: :cry: :cry:

sheshovel
01-14-2006, 09:05 PM
Uniscaper,I'm sure your pics are resized to 800x800
max correct?And they are saved in your file as JPEG
right?if so you are doing everything right..you just have to wait awhile after you hit upload...tell the window blinks and you see your file come up in blue writing.Then click "Browse" again and click on your next pic and upload again and wait for its blue name to show up then repeat for up to 5 pics.Then hit "close this window and write your message and then hit post.
I think your just not waiting long enough.
Job looks great..no fun in that kind of heat for sure!

UNISCAPER
01-15-2006, 01:00 PM
I should add a few things here. On the shots where you see the grid exposed and being installed, you actually create cells with fabric and washed rock. The grid on this poarticular job was installed every 24" of lift and soil hardness tests were made. We had to hit over 90% proctor scale compaction in order for the engineer to release us to build the next lift. In this case, the soils was crap and I would have lovd to use class 3 back fill, but, we had what we had. We created a mix plant where we added water while dumping, then drove the loads to the reinforcement zone.

WE would install the back fill at the farthest point on the grid first, after pulling the slack out of the grid. In an ideal world, if we could gain a 2" lift over the back of the block, and taper it to the same elevation as the block at the back of the zone, that helps when the soil consolidates.

All soil consolidates, no matter how hard you hit it to gain your 90% plus. Our objective by ramming soils with so many different weapons is to get the entire wall system to consolidate at the same time, so we have an even drop when consolidation occurs.

So, in answer to the original post, that is the way it is done by the book. You can see wals are not anything to be taken lightly. They are without a doubt, the highest risk aspect of the landscape industry.

GreenMonster
01-16-2006, 09:34 AM
So, in answer to the original post, that is the way it is done by the book. You can see wals are not anything to be taken lightly. They are without a doubt, the highest risk aspect of the landscape industry.

Bill thanks for the great info, and great pics.... well, thanks to Squizz I guess for the great pics :)

I guess when you say "by the book", well, that's why I started this whole thing. I've seen different pics and cross-sections of grid walls, from block mfg, grid mfg, etc and they all seem to be a little different. I've seen ones that don't call for and haven't shown fabric, with as little as 6" of drain field.

Let me ask a couple questions:

Isn't there a concern about these mfg that aren't calling for fabric behind the drain field? If you are using good crushed gravel and properly compacting, could you be ok?

If you wrap the drain field completely like you showed in one of your pictures, does it interfere with the aggregate lock on the grid?

I did a 4' reinforced grid wall where we had about a 1.5'-2' drain field, and then used 3/4" crushed gravel behind that. An engineer told me I could have just as easily used the 3/4" crushed stone to fill the entire reinforced area. Would you have concerns that the stone (no fines) wouldn't compact and hold the grid like the compacted crushed gravel (with fines).

Bill, is one of your pictures showing plywood to separate your drain field?

I'm by no means questioning any of your methods, Bill. They indeed seem to be the most proper. I'm just trying to clarify contradicting info I'm gettign from other industry sources.

UNISCAPER
01-16-2006, 10:29 AM
Mark:

The unfortunate part about contracting is there are at lease 6 different ways to do something correctly. Anyone who takes a hard lien stance continually on something being either right or wrong, is wrong themselves. There are definite ways you don't want to do something, and at the same time, there are many ways to get the job done to the specification. If a particular method works for you, the enginers pass it, and you are within the budgeted hours for the job, God bless you. The method I showed is the way Keystone ideally wants it's products to be installed in our terrible soils. There is much debate over fabric or not, so I'll tell you this. Every one of the soils engineers employed by Keystone at the seminar they sponsored at Vegas last year (Keystone University) said they prefer geotextile fabric around the 3/4 rock, not just around the pipe. The main reasons are that a 4" perf pipe uses about 12" of fabric to burrito wrap it, and there is only 12" of surface to clog. By wrapping the entire 18' lift of 3/4 rock in cells as we had done, you provide optimum drainage surface. To back up what the engineers taught at our class, the Geo-Technical firm used on this project inspected the wrap we had done, and required us to do it the way we did. Yes, those are 2' wide sheets of ply wood between the rock and the soil back fill. They have points on the bottom to keep the sheets from sliding when we dump the rock, and before we apply dirt. The pipe you see is a piece of 6" SDR-35, that we reduce to the 4" perf pipe behind the wall, and area drains are tied directly to the pipe so water can come off the plant zones behind each wall. WE routed the pipe around the perf pipe, you want to keep that as dry as you can so soils does not break down and fail. By using 3/4" rock and fabric, you will create a great deal of cohesion. Not as much as rock on rock, but you need not worry about sliding in the drain zone, if you hit 90% on the reinforcement zone, and the drainage rock is doing it's job, the grid will hold the wall as long as the soils do not saturate.

Anyhow, glad to be of help when I can..

GreenMonster
01-16-2006, 11:19 AM
There is much debate over fabric or not

Indeed. The Allan Block reps around here are almost taking a no comment stance on the fabric, which I find quite frustrating to say the least. I guess the worry is that the fabric can almost hold back too much water, and thereby create hydrostatic pressure. Obviously, on the other hand, you potentially have contamination of the drain field with fines if you don't have the fabric. But, if you're reaching 90%+ compaction, will the fines work into the drain field? I don't know. Walls have been built with fabric for years, but, maybe it's taken this long to see it's not needed. I just want to know the best way. Sure doesn't seem right NOT putting it there.:confused:

thanks for the pics and advise.

UNISCAPER
01-16-2006, 11:42 AM
Mark:

Reaching 90% is in the reinforcement zone. However, most SRW manufacturers are going to tell you to keep rammars, Wackers, heavy equipment 3' back from the pins, or connection joint and use a plate style compactor in that zone. You and I both know with dirt, you are going to be lucky to hit 85% on a good day using a vibratory plate compactor. That, and they are concerned about plasticity developing in the reinforcement zone which will create that silt you are worrying about, as well as loosen the grip the soil and grid have together. Though you may and I say may be able to get away with a weakened condition in the reinforcement zone, if you combine that with slit plugged 3/4", now you got hydrostatic pressure built up, and, nothing to tie back the wall because of the pudding you have for soil.

I'm thinking this fabric/no fabric thought is a regional thing. We have a pretty tough spot for SRW's. Often where you could get away with grid at 60% of the wall height, the norm here is 100% of wall hieght to help handle the seizmec requirements. Then, we have little to no rain. However, when it does rain, we have run off rather than saturation, unless it rains so much as it did last year that soil turns to muck, thus, the need to mechanically remove by use of plastic drain lines, water that pools over reinforcement zones.

Now, in your region, I remember many posting about lots of rain, rain that would devistate our area. I think, as it rains more regularly, the soils change into something that will absorb water, which our soils never would.

I dunno, I would love to get a soils engineers input on this fabric thing, what I mentioned is the only logical thing I can think of, but is pure speculation on my part.

UNISCAPER
01-18-2006, 07:43 PM
Ok, since the issue of pictures and the problems I had posting (thanks to Squizzy for getting them up) happened on this thread, I'll toss a bizzarre twist to the mix.

I rarely pay attenton to my computers desktop. So, I go on today and the phone rang, and before I clicked up a program, as I was speaking, I got a look at the desktop.....

Remember when I went through the motions to get those shots up here? And as Sheshovel mentioned that sometimes you gotta wait for the links to hit the thread reply screen??????

Well,it appears I have about a dozen shortcuts on my desktop that if you click, take you directly to the pictures I was trying to post. So, they went onto the upload box, and after a minute wait, they would dissappear rather than going to the post reply screen like they should.... Those suckers went to my desktop.....

Befoozled!

One last thing. I was asked by Keystone to do a presentation of the case study on the wall you see on this thread. The dates are the 15th and 16th of February at RCP Block and Brick. The 15th is in Lemon Grove, and the
16th will be in Escondido. If anyone is near and would like to see it, PM me. Also, that wall will be in this months Keystone newsletter called "Retaining Focus" which they have given me 300 copies to pass out to potential clients in an efrot to help build our business. I can't talk highly enough of how Keystone works with it's installers to help them get exposure.

kootoomootoo
01-18-2006, 09:05 PM
I'm looking at a fellow aussies pics and wondering why there is Mexicans .....:confused:

Got it now.

Squizzy246B
01-19-2006, 09:23 AM
I'm looking at a fellow aussies pics and wondering why there is Mexicans .....:confused:

Got it now.

Down Under: Mexican = Victorian:)

sheshovel
01-26-2006, 01:47 AM
One more thinkg I have to say about this wall is..not only will it stop the house from sliding down the hill..it will work as a great fire break in that area if a fire runs up that hill it could be the thing that saves the house in a wildfire situation

Squizzy246B
01-26-2006, 04:35 AM
One more thinkg I have to say about this wall is..not only will it stop the house from sliding down the hill..it will work as a great fire break in that area if a fire runs up that hill it could be the thing that saves the house in a wildfire situation

A pertinent point:

http://www.abc.net.au/ra/news/stories/s1552835.htm

http://en.chinabroadcast.cn/2239/2006-1-23/135@295120.htm

http://www.alertnet.org/thenews/newsdesk/SYD154016.htm

Can anybody point me towards a good website for Geo-Grid technical info??

neversatisfiedj
01-26-2006, 07:22 AM
How and who does a soil hardness test ? Is it necessary on all walls ?

--Josh

Squizzy246B
01-26-2006, 07:59 AM
How and who does a soil hardness test ? Is it necessary on all walls ?

--Josh

Josh, We build Mass Retaining Walls with Limestone. A MRW is an "all balls no brains" approach to the structural aspect of retaining...which is not to say it can't look fantastic. Anyways, the sheer mass of the wall, by engineering calculation, is what does the retaining.

The No 1 things that can cause an MRW to fail is lack of, or uneven, compaction. If you have a hard point at some point under the wall and soft elsewhere, the wall will settle more in the soft area and crack. Now because its an MRW its not often a problem, the wall can be repointed and there is no further problem after the settling has occured. However, its bad for your rep and it can cause major problems if water is behind the wall as well.

I test the footing area, with a penetrometer, for every wall we build. I look to always exceed the standard required for buildings but the main thing I'm looking for is a consistent result along the length. 7 blows in one spot at 12" and 10 in another is unacceptable to me and we dig out further, backfill with builders sand and compact again until we get it right. I have built over 100 MRW and I have not yet had a structural fracture.

Now, as I look to branch into different types of wall such SRW I don't see that I should change too much for the sandy soils we are building on. The principal should be the same although the mass is a lot lower. FYI our mass walls are often 1000 kg per metre or 2200lbs per 3'3" roughly and often as high as 2500kg per metre. An 8ft high wall we built recently went to 8800lbs per metre and we had the soils engineer do a compaction certificate.

Thats what we do anyway.

UNISCAPER
01-26-2006, 10:24 AM
A geo technical engineer is who does soil hardness testing. They either use the cone method ( mechanical method where they dig a cone shpaed amount of soil out of the ground, place it into a small tin, weigh it, then take it over to a hot plate and cook it to get the moisture out, then weigh it again.

Soil that is compacted properly will weigh an exact figure in the given amount they sample, considering that most soils and for that matter base, or DG weigh 110-115 pounds per cubic foot.

Or, they can use the nuclear testing device. They drop a plate with a spike onto the ground and hammer a probe into the soil. Then they turn on the machine and it sends out waves into the soil to test hardness. The engineers will randomly pick spots for you to have within spec, so that way you can't cherry an area out that you know will pass when other spots probably won't pass.

When they pull the machine off the soil it glows irendescent orange, cooling to yellow, and eventually comming back to it's natural color. That's a great place for heating up your burritos for linch during that time period.

All hardness is registered and cerified, then placed on file for future use, and in the event of a failure. Once the engineers sign off, you limited your liability by documenting soil hardness.



Everything but the glowing ground is true, they do use a nuker for hardness quite a bit, but most still use the method I just mentioned.

neversatisfiedj
01-26-2006, 11:02 AM
What size wall would you perform the test on. All walls ? Just massive walls ? Would you perform tests for small residetial 4 ft tall walls ?

UNISCAPER
01-26-2006, 10:09 PM
Any wall over 3' in San Diego County, any wall with load calcs over 200 PSI and any wall installed on or in the center of a descending toe slope would require soil hardness testingt.