Retaining Wall

881 views
23 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    February, 2013
  • 262 posts
Retaining Wall
Posted by PVT Kanaka on Friday, July 21, 2017 1:10 AM

OK,

 

Efforts to use OneDrive to post a photo to give a sense of the project opened a pathway to my entire family photo album (fascinating, I am sure, but a bit beyond the subject matter!), so I am going to have to try and describe this project with words.

The garden settled about 2" along a 48" length of track that more or less abutts the garden's retaining wall.  The finished project will thus only be visible from one side and, of course, from the top. 

From a practical standpoint, I just need to get the rails level.  From a visual standpoint, I want to take advantage of, rather than fight, some of the undulations in elevation from settling over the last 2 1/2 years. I want it to be solid enough to allow for adjustments as things continue to shift about, and I want to use the project as an excuse to dicker with some other tools and techniques. 

My thought was to use a hardiebacker sub-roadbed (snapped to size using a score-and-snap technique I recently learned about) mounted on some sort of core.  I had thought about foam, sealed behind latex paint, for the core which would keep the weight down and make it easier to adjust as required.  I would then glue foam to the side and score witha hot knife for texture.  I can also use something more substantive like bricks for the core if this would be better.  Thoughts?

I am also mulling scrapping the whole retaining wall idea and, instead, building a bridge and leveling out the garden bed underneath.  This would be something simple, using some techniques Tom shared in another one of my posts.  It would accomplish the same thing, I think, but I am not sure how it would look.

As ever, I would appreciate any "guidance to the helm!"

 

Aloha,

Eric

 

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Friday, July 21, 2017 7:22 AM

Eric

Ground subsidence will be an issue for several more years. You say you have about 2 inches of subsidence in 2 1/2 years. In another 2~3 years you should expect another inch to 1 1/2 inch more subsidence, and so on over the next dozen or so years. Be prepared to repeat whatever you do this season in a few more years. The quick fix would be to get a 5 gallon bucket of crusher fines. Pile up a bunch between the rails followed by vertically shaking the track allowing the fines to settle under the ties. Repeat as needed to raise the track to the desired level. Add this task to your yearly late spring time to do list. I say late spring due to my experience, most of my subsidence (yes, I still fight subsidence after 17+ years) occurs during winter/ early spring.

You also stated you want to experiment and develop more skills, while keeping the uneven natural low areas for the visual effect. A 48 inch long, 2~3 inch tall bridge will be a great visual enhancement. If you go with a timber trestle bridge be prepared for annual maintenance.  As the ground under the bridge continues to subside some posts will lift out of the ground while others will drop along with the soil. A through truss bridge set atop concrete piers might be a better choice, but MUCH more work. Build a wooden form to make a series of identical piers that reach down 5~6 inches below current ground level. You could experiment with making a rubber mold to make the piers. These piers would need to be supported by a structure that reaches down to at least 3~5 inches below the original grass level from before you built the GRR. Just a couple of possible support methods; (1) Get some red bricks and split them in half and dry stack them from below grass level to a point 4~5 inches below current ground level place your piers atop the stack. (2) Get some ABS pipe (black PVC), dig them in below the grass level, fill with mortar mix and top with the piers. In either case as your fill continues to subside the ground level will slip down the side of your piers doing away with any need to backfill under the bridge. I would recommend not using any backer board as it will it will expose itself as the subsidence continues over the years. Unless you could find a way to anchor the board to your retaining walls. 

 

My experience with major subsidence is in an area where the track crosses a rose bed, a 30 inch wide, 36 inch deep trench filled with compost. The compost fill went in during the summer of 1995 and still continues to subside. My solution was to dig down and place a cedar 2x4 spanning the gap plus a foot on each side of the trench into the clay, original 'soil' my house is built upon. I set a timber trestle bridge atop the 2x4 to support the rails and backfilled with more compost. I am at a point where I can no longer backfill with more compost as it would bury the the main branches unless I dig and lift up the rose bushes, way more work than I'm willing to do.

I'm interested to hear how you solve your issue. 

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Friday, July 21, 2017 7:33 AM

Photo sharing. Most of the older sites we have used over the years have begun shutting off 'third party' photo sharing. I just got a message from Photobucket that 'third party' sharing will quickly end unless I spend more money to keep that feature. Not so willing to pay the added fees.

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Saturday, July 22, 2017 5:52 PM
Tom, lots to mull over...To be clear, do I have to dig down below the grass, or just into the raised bed? The GRR is about 2' off the ground, with the first 20" dirt, and the rest gravel to the top, except where our plantings have gone in. In the meantime, I have a few other repairs I am doing as I chew this over. Oh, yeah, I also refuse to pay the Photobucket fee. Not sure what to do now for photo sharing. Enjoy your weekend! Eric
Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Saturday, July 22, 2017 8:30 PM

Eric

Sorry, but yep.

In order to completely defeat subsidence of track right of way one must go below the lowest known layer of decomposing green matter. Not knowing how much green matter is in your fill soil, I'm sure there is some, possibly up to 15~20%. If I recall correctly your buried your lawn under the empire. Look at a cross section of the average lawn. Below the grass line is the root zone 2 to 2 1/2 inches deep. Below that is a zone of decomposing older roots, another 2 or so inches. If your intent is to totally defeat subsidence you will need to go at least 6 inches below the grass line for support.

You are fighting two types of subsidence. First being the decomposition of green matter which depending upon the type of green matter, water content and aeration takes 6 to 10 years, possibly longer. Secondly, you have normal soil compaction, which will continue for a few hundred thousand years until it turns to rock. Even if you were to dig two feet below the grass line you will still experience subsidence in the neighborhood of a quarter inch per ten years. Subsidence is just something we learn to live with. Don't get too depressed and think all is lost. If you decide to go with a truss type bridge with cement piers reaching down about 5 inches or so into your fill soil your subsidence rate should drop to 1/4 inch or so per year. If the piers drop completely vertically all you would need to do would be to use timbers (wood shims) to level out the bridge every couple years. Every year the rate of subsidence will get a bit less and less.

My new "still under construction" empire is experiencing subsidence. 4 years ago I built a 4 foot retaining wall and put in about 36 inches of decomposed granite. Every year since I've hired local day laborers to add another 5 yards of DG about 2 inches. As it continues to compact by age the level gets a bit lower each year. A broken hip and couple surgeries have slowed construction a bit. I had it at 12 inches from being level full, added six more inches and still have 8 to go.

Most of us have just allowed subsidence to do its thing and add the task of re-ballasting the track yearly to raise track level. If I had your problem I would get some 1/2" or 3/4" coper pipe and add culverts before backfilling with ballast. I would then add some timber (or cement) header and wing walls to the pipe at least half inch above the new 'ballast slope line'. By 'cement' I mean mortar mix. Track running atop a levee or dike is very normal in the 1:1 scale.

Pro's and Con's: Lifting the rails by re-ballasting will take about half an hour and you are running trains again. Building a bridge. This is NOT a single day project. Digging shallow, depending upon available work time, could take a couple weeks of no trains. Digging deep could add another week or two.

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Saturday, July 22, 2017 8:40 PM

PVT Kanaka

Oh, yeah, I also refuse to pay the Photobucket fee. Not sure what to do now for photo sharing. 

Photobucket, like other photo sharing sites is a business. Over the years I have had them make me some oversized prints of some of my photos, as a way of paying for their service. I already pay for two cloud storage sites and am not interested in paying for another.

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Sunday, July 23, 2017 1:02 AM

An after thought. You are currently concerned about one small section. How is the rest of your track doing? Look close, I'm sure you might find some settlement in other older areas with lesser subsidence. 

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Sunday, July 23, 2017 2:39 AM

Tom,

For the moment, one section.  I had some slight settling elsewhere, but I just backfilled the whole area based on future plans of what I wanted to to in those spots.

In this area, our little guppy pond is in the center.  Along one side, I shored things up with broken concrete slabs, glued scale timbers to it, and called it a day.  Along another, I used a line of scale "boulders" to serve as a wall wall to hold up the gravel fill.  I nice grove of blue daze effectively does the same thing on the third side.  This side is the longest run of track, so I thought something a bit more permanent would be in order.  Been working on what that would be all afternoon and evening.

There is an overhead shot in my build log "Progress on the Triple " to orient yourself.  Oh, and issues with any site making its fair profit; I just am already paying for one site, and I have too many log-ins to remember as it is!

Thanks again for you very in depth answers.  Since the trains run fine, I am going to take a real stock of my options and resources before committing to any one course of action.

 

- Eric

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Sunday, July 23, 2017 8:55 PM
Tom, As I chew on all this, I think I am going to have to forgo the bridge idea. Realistic assessment of available time indicates this would take trains out of operation for months. Also, as there is at least a theoretical plan to turn our guppy pond into a proper water feature, a project of this nature could be premature. I like the culvert-and-wings suggestion. This seems more flexible over the long term, and more repeatable when required elsewhere along the line. And, it should allow for the development of modeling skills, albeit in smaller and more likely to be accomplished chunks! OK, enough theorizing...The sun is hitting the crest of the Ko'olaus, and it is time to get a train or two running in Olomana's shadow! Aloha, Eric
  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Monday, July 24, 2017 11:58 PM

Tom,

Allegedly using the link from OneDrive will not give the world access to my family album; unfortunately, despite what their help desk said, that does not appear to be the case...

Anyway, I think the culvert approach will work best based on some internet searches, my available time, and my available tools and talent.  As silly as it seems, I just couldn't think of a good way to make the wings around the pipe. My tools include a good electric drill, my Dremel, a circular saw, and various gardening tools. Making a form into which I could pour concrete would be at the outer limit of my tools and capabilities, I would think. I was thinking of basically drilling into hollow tile, adding the pipe, the using construction glue to add a wooden top and wings.  The theory being that I could always lift out the whole assembly, back fill the hole, and reposition it if I had to.  Alternatively, what about timber cribbing?  I could cut some timbers to standard sizes, stack them into squares or rectangles, and drill holes in the corners for a screw to hold the lot together.  Then just backfill with the gravel and, hopefully, have a workable solution.

Anyway, hope this helps to frame the problem better.  I'll keep dickering with the photo link issue, and hopefully be better able to frame this issue soon!

Aloha,

Eric

 

 

 

 

 

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Tuesday, July 25, 2017 5:59 AM

Quick hint for culvert construction. Timber is quick, easy and commonly used. 'Concrete' (mortar mix); Build a multi use form. Use a piece of 1/2 inch or 3/4 inch plywood as a base. Drill a hole through the plywood very slightly larger than the diameter of the pipe you are using. Use 1/2 x 1/2 wood strips to make the outline of the header wall and wing walls. Lay the wood strips out to form the header wall, a rectangular shape of about 2 1/2 inches tall and 4 inches wide. The 'pipe hole' should be about 1/2 inch above the bottom of the headwall. WingWalls: 4 inches across the bottom, 2 1/2 inch tall on one side and 1 inch tall on the other side. CAUTION: wood will wick away the water in the motar mix too fast for the motar to properly set up. Use some GAA (grease automotive and aircraft) and coat the wood with a thin layer making sure to work it into the joints between the plywood and wood stips to fill any holes and gaps. Put a good coating in the pipe hole, but not on the pipe. Insert the pipe and fill with mortar mix, cover with wet paper towle and set aside for a day or two. Before inserting the pipe use some 40~60 grit sandpaper and spin the pipe to put some small grooving in the pipe. The grooves will help the motar mix to hold the pipe. I've had some problems using white lithium grease and prefer the regular stuff. The grease works well as a release agent when removing the walls from the forms. After the mortar has well setup, gently turn the form upside down and the pieces should fall out with ease. I usually break about 1 in 10 of my 'walls', just pour another as needed. Since wingwalls normally attach the the header wall at an angle there are two possible ways to attach. (1) Lay some coarse sandpaper on a flat surface and gently remove a little bit from the back corner so you get the angle you want. Glue the walls together with some adheseve or a bit of wet mortar.  (2) Without sanding the edge, just position the wingwalls in place and fill the gap with mortar mix. If you want a double pipe culvert just make the headwall form a bit wider to allow for the second pipe. 

The 'real fun' begins when the culvert is seen from the other side. Before attaching the wingwalls I stand the pipe back into the form with some spacer wood to support the cured headerwall above the form at the needed height. Take care to ensure that everything is aligned so that the headers match. I normally attach the wingwalls after the pipe is in place and use the backfill to hold everything in alignment.

When placing the pipe and headwalls the pipe should be at ground level. After everything has been set in place come back and remove a bit of the fill so there is a small hole in the ground at the pipe, normal erosion from running water as it comes out of the pipe.

How to 'cheat' with timber construction. Instead of gluing up a wall of individual timbers I take a piece of 1x6, run it through the table saw so it ends up about half inch thick. On the "clean' side I scribe in the individual timbers with a metal ruler and a sharp razor knife. I use several different stains to color the individual timbers. 2 cans of stain = 2 colors, mix 50/50 for third color, mix 3 parts 1 part gives two more colors. Use a toothpick to paint in the grooves with black india ink.

Sorry about the 'maximum verbosity', but when I get going I just cannot stop.

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Tuesday, July 25, 2017 7:26 PM

PVT Kanaka

Tom,

Allegedly using the link from OneDrive will not give the world access to my family album; unfortunately, despite what their help desk said, that does not appear to be the case...

 

Have a look at my "interesting bash" post then read the instructions in second post.

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Wednesday, July 26, 2017 2:56 AM
Tom, No worries about the verbosity. Both approaches are within my skill and toolkit. I think the scored board will work in the longer area, solving the immediate problem, and the form is something I can hold in reserve for troubleshooting and spot repairs! Also, thanks for the OneDrive tip. It is late, so I will try to monkey with it again tomorrow. Aloha! Eric
  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Friday, July 28, 2017 12:52 AM

 Still trying to get the blasted photo to post...

 

Note I did have to use the "insert image button," and I hope it does not lead to my whole OneDrive (Opening the picture on CINCHOUSE's computer only led to her OneDrive).  Anyhow...

Now you can see the degree of settling in terms of depth and length.  As mentioned, I am going to use the scored board method here.  Assuming this photo does not give everyone access to our family album, I'll update this when I get underway with the project.

Aloha,

Eric

 

 

  • Member since
    July, 2003
  • From: S.Easton , Mass.
  • 588 posts
Posted by smcgill on Friday, July 28, 2017 7:32 AM

I'm just seeing the one pic! Thumbs Up

Mischief

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Friday, July 28, 2017 8:15 PM

Only the one pic shows up. There is one thing a bit strange. Normally clicking on the pic opens it up in a new window. A click saves it to my hard drive. "Open in new tab, open in new window also saves to har drive. Strange.

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Friday, July 28, 2017 9:24 PM

HUZZAH!!!  Semi-success!  I had the same thing when I was working wiht this, that it would open and try to save the picture to my drive.  As you said, strange...

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Sunday, July 30, 2017 8:52 PM
Tom, Stain is on hand, and the hardware store has the appropriate bits of scrap wood. I am going to see if I can get the 1x6 for free this week before commencing OPERATION RETAINING wall. Likewise, all material on hand or sourced for the culverts, but, as concrete and mortar mix has a short half life in the tropics, I am going to hold on that technique, other than the mold, until I need the mix for a household repair...something that appears almost as fast as mortar mix fails in the tropics! Aloha, Eric
  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Monday, August 07, 2017 1:38 AM

Tom,

Scored a board, using the ties of my LGB track to size the lines.  Figured I'd make the wall look like it was made of railroad ties.  I did  not score the bottom two inches, as the wood splintered when my father-in-law cut it down, it will be hidden, anways, and as it is a plywood, not solidwood, I doubt this wall will live to see the garden settle a full 6", anyway!  I will see if I can get this stained over the week.

I also bough the material for the culverts and forms, so that I have the forms on hand for the next phase of the project, which will be to shore up some random places about the garden, possibly leading to some scenic developmeent as we go.

 

FYI, the concrete walls and wings are very similar to stream crossing points along the Oahu Rail & Land mainline my oldest daughter and I found up beyond Mokuleia, so I could see these forms doubling for some short, basic bridges, too.  In 25-30 years, we may have a real representation of a Hawai'i sugar cane road after all!

Thanks again for the tips, and I will keep you posted with the progress!

Have a great week!

Aloha, 
Eric

 

 

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Monday, August 07, 2017 2:01 AM

PVT Kanaka
I am going to hold on that technique, other than the mold, until I need the mix for a household repair...something that appears almost as fast as mortar mix fails in the tropics! Aloha, Eric 

Eric, Do you have access to volcano ash? If so, do like the Romans did, add 1 part ash to 4 parts mortar mix. Better yet, mix equal parts cement and ash. It beefs up the water resistance of cement. Some of their bridge piers poured under water are still in use to this day. The ash/cement mix is extra light and extra, extra strong. Rome has several domed buildings that have been standing for over two thousand years.

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Tuesday, August 08, 2017 2:33 AM
Alas, Pele vents her frustrations from Kilauea in the form of a lava flow! Ash is atypical in any meaningful amount on O'ahu. Neat, neat idea though!
  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Sunday, August 13, 2017 7:59 PM

Tom,

The wall (and a good portion of my girls!) is stained as you described.  The photo is pretty bad due to the sun, but multiple tones are visible.  Prior to staining, I did deepen my grooves with my Dremel (love that thing!), setting it at a low speed.  The India ink is on hand, but I want to see how everything looks when it dries before I apply it. I used a pretty dark stain as a base, so I may have inadvertently obviated that step!  I should be able to remove my not-so-deccartive concrete shards by the end of the week, shoring up a good  section of the run with this retaining wall.  

Oh, I shattered two swords at my fencing club, which provides some high tensile "rebar" to brace this new "wall."  Should I do that, or will the dirt and stone fill be sufficient to hold the "wall" in place?

Thanks as always, and have great week!

Aloha,

Eric

P.S. I will, if nothing else, have a photo of the project after it is installed.

Moderator
  • Member since
    February, 2004
  • From: North, San Diego Co., CA
  • 2,948 posts
Posted by ttrigg on Sunday, August 13, 2017 9:39 PM

India Ink should be applyed to the raw wood. It is water based solution and will soak deep into the wood. Over time as moisture seeps through from the backside of the wood the ink will migrate back to the surface. Stains are oil based and will seal the ink in place. Suggestion; put the wood header board in place and let it age 4~6 weeks to allow the VOCs to evaporate then apply the ink, cover with a thin coat of the very lightest stain you have after the ink has dried for a couple days. The real effect you are trying to achieve will happen in about 2~4 years as the color will change to 'barn wood grey'.

 

As for the 're-bar', should not be needed. If it is the type of sword I'm thinking about, it may introduce a 'sheer plane' (think miniature earthquake fault zone) that will allow, and possibly accelerate, road bed materials to move. Not sure what you mean "stone and dirt". If you build up the roadbed with shoulders 1/2~3/4 inch wider than the ends of the ties, you should be good to go. After the first rain you will see some washout, not a big concern, just add more ballast. As the elevated roadbed ages it will firm up and become more stable. If you have wing walls for the head wall it should stay in place just fine unless hit by an 0-5-0.

  • Member since
    February, 2013
  • 262 posts
Posted by PVT Kanaka on Tuesday, August 15, 2017 12:30 AM

Ah.  Ink first, then stain.  Live and learn!  We will get this first wall in place then by this weekend, which will let us proceed to the wing wall and culvert project, hopefully brining this part of the operation to a conclusion.  

We'll put the lessons learned into the next timber wall, which we can tackle as wing walls and culverts start to come out of the mold.  Should carry us through the summer.

Thanks as always, Tom!

- Eric

 

SUBSCRIBER & MEMBER LOGIN

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

FREE EMAIL NEWSLETTER

Get the Garden Railways newsletter delivered to your inbox twice a month

Search the Community