Hire the best Concreting Expert

broken retainer wall

Results 1 to 42 of 42
  1. #1
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Post broken retainer wall

    I live in a house on a hillside slope and on the backside of my property is a 3-4 ft. tall concrete retainer wall. Recently, a 3.5ft. x 5 ft. section of the wall on the side of the backyard broke out and had to be broken up and removed. Now, I must find a reasonable way to repair the break in the wall. The slope is a steep incline and the soil is soft and unstable, so the work will be a bit of a challenge. Attached are two JPEGS of a couple of ideas on how to approach this repair. The "POUR" idea would be the most difficut to accomplish on a sharp incline and would require about 40 sacks of concrete. The "BLOCK" idea would be easier but I haven't figured out how the blocks will meet the broken concrete ends of the wall. In short, I'm looking for suggestions on an easier or more practical solution to repair this broken wall. I realize this is not the ideal structural solution, but I cannot afford to replce the entire wall. Any CONSTRUCTIVE suggestions would be appreciated.
    Thank you,
    worrell
    Attached Thumbnails Attached Thumbnails pour_retainer_wall.jpg   block_retainer_wall.jpg  

  2. #2
    Seasoned DIY droog's Avatar
    Join Date
    Sep 2005
    Location
    Bendigo
    Age
    57
    Posts
    2,556

    Default

    Here in Australia in most areas a retaining wall of that height would require engineering and sign off from the local council.
    Not sure what your local requirements are, but most of the design is in the footings for the structure. What is the existing footing and has the collapse damaged that existing footing ?

  3. #3
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Quote Originally Posted by droog View Post
    Here in Australia in most areas a retaining wall of that height would require engineering and sign off from the local council.
    Not sure what your local requirements are, but most of the design is in the footings for the structure. What is the existing footing and has the collapse damaged that existing footing ?
    Thanks for your input.
    This house and most likely the retainer wall as well was built in the 1940s. There is no existing footing. This will be a "best you can" repair. I figured a 12'"x 12" concrete and rebar footing would be sufficient for a 3.5' x 5' repair.

  4. #4
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    The only relatively easy fix that existed, that is to prop and support the section that broke, has been taken away.
    A retaining wall, like a dam, works as a continuous structure. Once that continuity is cut, you need not only to reconnect both ends, but to rebuild the footing that stops the wall from toppling over. The fix involves digging out a substantial amount of soil behind the area to be rebuilt and behind both ends of the interrupted wall. Uncover footings at both ends and expose reo bars. formwork, weld new reo steel and pour.

    Any attempt at plugging the hole with a structure that stops the soil from flowing out the hole relying on both ends of the existing wall, will condemn boht the existing wall to collapse down the track.
    No easy fix here. And I would say that unless you are a serious builder aficionado, this is not a DIY project. Contact a concreter. If you have slopes to contend with, you will also need a concrete pump.

    It is also important to investigate why the wall failed. Was the concrete quality dubious? Are there other cracks in the remaining wall? Is there sufficient existing drain to let water that builds up behind the wall flow out?
    Any fix even a proper one, will impose additional load to the two sides remaining. It would be a shame to spend money on a fix only to see the wall fail somewhere else. Water is the main cause of retaining walls failing.

  5. #5
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Thank you Marc.
    I have had several concreters look at the wall and they don't want the job. I think this is a "do the best you can" repair. The wall was not done properly to start with and I cannot afford to replace it. And yes, water is the cause.



    Quote Originally Posted by Marc View Post
    The only relatively easy fix that existed, that is to prop and support the section that broke, has been taken away.
    A retaining wall, like a dam, works as a continuous structure. Once that continuity is cut, you need not only to reconnect both ends, but to rebuild the footing that stops the wall from toppling over. The fix involves digging out a substantial amount of soil behind the area to be rebuilt and behind both ends of the interrupted wall. Uncover footings at both ends and expose reo bars. formwork, weld new reo steel and pour.

    Any attempt at plugging the hole with a structure that stops the soil from flowing out the hole relying on both ends of the existing wall, will condemn boht the existing wall to collapse down the track.
    No easy fix here. And I would say that unless you are a serious builder aficionado, this is not a DIY project. Contact a concreter. If you have slopes to contend with, you will also need a concrete pump.

    It is also important to investigate why the wall failed. Was the concrete quality dubious? Are there other cracks in the remaining wall? Is there sufficient existing drain to let water that builds up behind the wall flow out?
    Any fix even a proper one, will impose additional load to the two sides remaining. It would be a shame to spend money on a fix only to see the wall fail somewhere else. Water is the main cause of retaining walls failing.

  6. #6
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    If that' the case, and if aesthetics are not important, you can start by digging out some of the soil behind the collapsed section, but don't go too far, you will have to shovel it all back in.
    Place a row of 4 or 5 sturdy post as deep in the ground as you can. Keep the tops lined up with the top of the wall. Run a reo bar from each post back into the ground above as far as practicable and into an anchor; a piece of same material as the post buried across and holding the post back. The first and the last post needs to be outside the existing wall holding the ends of the wall back.
    Next find planks of concrete, sleepers, steel H beams, roofing material, or whatever you can find cheap and strong to pile up against the post from the inside of the hole.
    Fill the hole back. Make sure water can flow between the material you use.

    This is just to give you an idea, the fine details of how to, will take much more writing up.
    There are also many different ways to do this.

    The key of this method's success is in the proper installation of the anchor, and the tensioning of the reins, be they reo bar or steel cable or chains.
    An excavator would be a good tool to have if terrain allows it, to dig and to give the reins tension.

    You could also stabilise the ends of both walls with this method, but build a wall tapering back with heavy blocks between the post. Landscape suppliers will have a variety of heavy blocks to build retaining walls in your area. Choose the heavy sort that does not need mortar and that interlocks with pins or steps. If you go one row at the time and set it back far enough, you can pretend they are access steps.

  7. #7
    Senior Member
    Join Date
    Apr 2018
    Location
    Western Australia
    Posts
    403

    Default

    Personally I would be going with an concrete post and panel system just in front of the existing wall/footings. There should be something equivalent rated over there and the supplier should be able to supply the engineering cert for the height being installed.
    You can DIY install it as long as you have a concrete mixer. In soft ground its about a 350mm diameter hole for 900mm high so not a premix bag job. I've done it up to a retained height of 1.25m, but at that height the posts are actually 2.4m long and at the limit of one person lifting.

    While a bit time consuming to do it's pretty cheap and will last. Good thing is any moisture will weep through the panel joins and not build up behind too much.
    Your better off fixing it now than waiting on the rest of the wall to start collapsing.
    Attached Thumbnails Attached Thumbnails panelandpost2.jpg  

  8. #8
    1K Club Member Gooner's Avatar
    Join Date
    Nov 2007
    Location
    Melbourne
    Age
    46
    Posts
    1,059

    Default

    No one commented on the quality of the sketch and superimposed CAD models. Nice work.
    I'm no expert, but know enough to be dangerous...
    __________________

  9. #9
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Thank you Marc.
    I will draw up something and post it so you can see if I'm understanding your explanation properly.


    Quote Originally Posted by Marc View Post
    If that' the case, and if aesthetics are not important, you can start by digging out some of the soil behind the collapsed section, but don't go too far, you will have to shovel it all back in.
    Place a row of 4 or 5 sturdy post as deep in the ground as you can. Keep the tops lined up with the top of the wall. Run a reo bar from each post back into the ground above as far as practicable and into an anchor; a piece of same material as the post buried across and holding the post back. The first and the last post needs to be outside the existing wall holding the ends of the wall back.
    Next find planks of concrete, sleepers, steel H beams, roofing material, or whatever you can find cheap and strong to pile up against the post from the inside of the hole.
    Fill the hole back. Make sure water can flow between the material you use.

    This is just to give you an idea, the fine details of how to, will take much more writing up.
    There are also many different ways to do this.

    The key of this method's success is in the proper installation of the anchor, and the tensioning of the reins, be they reo bar or steel cable or chains.
    An excavator would be a good tool to have if terrain allows it, to dig and to give the reins tension.

    You could also stabilise the ends of both walls with this method, but build a wall tapering back with heavy blocks between the post. Landscape suppliers will have a variety of heavy blocks to build retaining walls in your area. Choose the heavy sort that does not need mortar and that interlocks with pins or steps. If you go one row at the time and set it back far enough, you can pretend they are access steps.

  10. #10
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Thank you Doovalacky. I will investigate this idea further.

  11. #11
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Thank you Gooner.

  12. #12
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    This sort of blocks will make the patch up easy:
    https://www.rcpblock.com/walls-californiachateau.html

  13. #13
    Golden Member
    Join Date
    Oct 2017
    Location
    Melbourne - Yarra Ranges
    Posts
    682

    Default

    some photo's of your broken wall and surrounding area would be nice
    Do you know if any foundations exist, how big and what type they are - crushed rock or concrete?
    Does reo bar exist in the concrete walls?
    How thick are the current walls?

    The unknown here is what its supporting? Whats behind the fence? ie: the unknown complication we cannot see sitting here behind the desk!!
    How unstable the soil is etc etc....a concreter not wanting the job may indicate the complexity or risk of the job failing.

    ......which maybe option 2 and 3 below might be fit for purpose. They dont require massive holes to be dug with lots of concrete, will allow for some movement without the wall failing or heaved over (over time) within reason but good foundations are key which could simply be compacted crushed rock.

    Here are some options:

    Similar to Doovalacky suggestion - dig 2 holes in front of and either side of the broken wall. Looking at your sketch, we are talking of a 2 meter wide wall?
    Use some C or H beams and sleepers slotted in (wood or concrete). Id also be putting in scorier rock half way up (some sort of free drainage rock), and geo textile to stop the soil blocking it all up over time with and outlet to drain the water. Normally the post go as deep as they are high but your soft and unstable soil may require a greater depth and circumference of the hole to be filled with concrete.

    The other option might be to put a good footing in if one doesn't exist (compacted crushed rock) and use retaining wall blocks which are dry laid however long term, not sure how each broken end of the existing wall will perform.....that the unknown here. This could go in between or in front. Need good drainage behind.

    Gabion cages although looking at your sketch, may not be a lot of room to dig behind without affecting the fence....unless you dont mind it sticking out the front....or build it in front of the existing wall 2.5 meters wide. geo textile behind.

    You could go with your concrete blocks, but make sure you have good foundations...generally a lot wider behind the wall than the brick with rebar and good drainage.
    Attached Thumbnails Attached Thumbnails wall4.jpg   wall1.jpg   wall-3.jpg   wall-2.jpg  

  14. #14
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Many thanks for your generousity Marc, that's a lot to think about.
    Last edited by worrell; 17th Feb 2021 at 01:10 PM. Reason: clearer.

  15. #15
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Bart 1080,
    Thanks for your generous response. You and Marc have given me a lot to think about.

    To answer your questions:
    Do you know if any foundations exist, how big and what type they are - crushed rock or concrete?
    There doesn't seem to be much of any foundation underneath. The wall continues into the soil maybe a foot or less.
    Does reo bar exist in the concrete walls? 2 horizontals and 3 verticals over the 5 ft. length.
    How thick are the current walls? 8 to 10 inches.

    The unknown here is what its supporting? Whats behind the fence? Soft and unstable soil up to the top of the 3 to 3.5 ft. wall.
    How unstable the soil is etc etc....a concreter not wanting the job may indicate the complexity or risk of the job failing. They didn't want the job because it looks dangerous. The slope is a sharp incline and the soil is loose.
    Thanks again for your help,
    worrell

  16. #16
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default



    I like this idea to stabilise the fill behind the wall. If the mesh is strong enough and locked in the block by a pin or reo, and repeated in each row of blocks, the wall will be very stable and will not be able to move forward.

    If your concrete wall does not have footings going down and then back under the soil to be supported, that is the cause of the fail.

  17. #17
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    So there doesn't need to be a concrete footing as long as there is a significant gravel base?

  18. #18
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Bart 1080,
    "The other option might be to put a good footing in if one doesn't exist (compacted crushed rock) and use retaining wall blocks which are dry laid however long term, not sure how each broken end of the existing wall will perform.....that the unknown here.
    This could go in between or in front. Need good drainage behind."

    If I choose to go in between the broken ends with the concrete blocks, how do the blocks meet up to the broken wall ends?

  19. #19
    Golden Member
    Join Date
    Oct 2017
    Location
    Melbourne - Yarra Ranges
    Posts
    682

    Default

    Cut the blocks to fit. fill gaps with mortar of maybe crushed rock to allow water seepage and not build up behind the wall on the lower end.
    You could also vertical cut the existing wall for a better face to cut/butt your blocks into.

    Its only ~ 2 m long, but you will have to step the blocks up the slope. Start from the lower end. Here is a utube video that gives you a good idea of the sequence required.
    https://www.youtube.com/watch?v=TtIX...nel=AllanBlock

  20. #20
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    Quote Originally Posted by worrell View Post
    So there doesn't need to be a concrete footing as long as there is a significant gravel base?
    I still don't understand why nobody wants to do this job for you. It is a mickey mouse job.
    Anyway. It seems you are concerned about the footings. You can do this without digging footings if you use a gabion. Search youtube for gabion retaining wall.
    Gabion is Italian for 'big cage' ... (sort of, spelled gabbione).
    Build a cage, fill with stones, job done. You will still need to put two post one on each side supporting the end of the existing wall, and have the gabion inside the opening, keeping everything flush ... or ... you can build the gabion outside the wall ends and supporting the wall and the soil.

    Here is one DIY gabion.
    https://www.youtube.com/watch?v=QFjEWnA3Mtc

    You can of course buy all the bits ready made for you from a supplier.
    https://www.youtube.com/watch?v=NYugg1EFFLM

    Gabions in california : https://gabion1.com/

  21. #21
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Hey Marc and Bart,
    I love the gabion idea but I'm wondering how practical that would be on a steep incline, especially without a footing. Even with a gravel footing it will occasionally be up against torrential rains.
    Once again, I appreciate your input.

  22. #22
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    We use gabions to stabilise riverbanks against erosion. No footing and you can't get more water than in a river.
    Can you draw a profile of the incline with grades?

    The stability of gabions is in the mass and width of the base. For your application I would go for something that is as wide (deep) as it is high.

  23. #23
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Can you draw a profile of the incline with grades?
    I will give it a try as soon as I can.

  24. #24
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Marc,
    I don't know if this drawing is enough information, but it's a bit more.
    Attached Thumbnails Attached Thumbnails profile_retainer_wall.jpg  

  25. #25
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Marc,
    Here is another drawing of an idea for a sleeper/gabion retaining wall.
    I'm wondering about the width of the steel column. Specifically how far in I need to go to secure the ends of the existing wall. Eight inches isn't much but I'm concerned about the weight of the 6 ft. column and maneuvering it into place for install. Also, I would need to create a nearly straight line at the ends of the existing wall, which would be challenging. Please let me know what you think and many thanks for your input.
    Attached Thumbnails Attached Thumbnails sleeper.gabion_retainer_wall.jpg  

  26. #26
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    Yes, I like your plan.

    I like your T shaped column, but, considering you are in soft sandy soil, the concrete in the footing will not be able to keep the column vertical under pressure, aggravated by the slope. You need to tighten the top of the column using a rein back past the fence and into a wide and deep anchor. if it is not your property, you surely can negotiate access considering it will all be underground and not visible.
    It is the edge of the concrete footing against the soil that does all the work. Sure you could dig a deep trench to cement the columns in but you will be making a rod for your own back.

    Normally the gabion should be 3 feet deep, if you go 3 feet up, but considering the boundary, your concrete rails will compensate the narrow base and should give enough support against horizontal forces, if you can either tie the top of the columns back or brace them from the front with another post at 45. (Probably ugly?)

    The 17 degree slope is not an issue and does not explain the reluctance of concreters to do this small job. Any excavator can work front on, on a 20 degree slope.

    The fill in the gabion should be rock. Rubble can be too light for a good result, unless you can find solid concrete pieces, like concreting samples used for testing, nicely packed.

    Your schematics are tops

    PS

    If bracing with a second post is out of the question and no access behind the fence, you could in theory brace the footings. Do everything as you designed, but add a trench in front of each post at 90 degree, same depth extending 3 feet down the slope. Your footings will gain a lot of leverage and be able to keep the patch vertical permanently. In normal circumstances, with solid soil and level surface, 3' deep for 3' high wall should be enough. Not in your case.

    PS of PS

    If you can dig further under the fence, and come with the gabion all the way to the front of the wall, and achieve same depth as hight. You need nothing else, besides the T post to keep the edge of the concrete wall in place.

  27. #27
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Hey Marc,
    I should have indicated earlier that the wall is facing my neighbors property and what is on the other side of the fence is mine. Frankly, I proposed this idea because the gabion alone my neighbor will most likely not be agreeable to, so I suppose aesthetics is an issue.
    I'm unclear about what form the "rein back" would take. Is this just an "L" shaped angle steel buried in another concrete hole behind the fence?
    Also, what about the steel column top profile in the drawing? Is 8 inches in enough to hold the existing wall ends?

    Thanks for all your thoughts on this.

  28. #28
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    Interesting. So the land beside the fence in the picture is your property. Is the land flat on your side?

    So this actually makes things easier. All you need is to take off one section of the fence, dig to your heart content and have a nice one meter wide gabion covering the opening and further, I would also go half a meter behind each end of the existing wall. Hiring an excavator would be nice, or convene a bunch or really strong friends
    That will give you a solid plug to this retaining wall. If you need to have something that looks nicer than stones to please the neighbour (Do you share the cost of the repair with the neighbour?) you can use whatever is pleasing to the eye, kept in place by the T steel columns.

    As for the column and reins ... 8" is plenty to keep the wall in place, providing the concrete is sound at that point. If the concrete is cut straight, even 4" would do.

    As for the reins, you need a long section of steel that will not rust (galvanised and painted for example) to pull the top of the column and impede it going forward. How to achieve this? ... you can use a 2"x2"x1/4" angle and weld a 3/4" all thread at each end so you can use the thread to tension it.
    A round bar would work too.
    The anchor can be anything steel, like a piece of 3' H beam or U beam with a hole in it for the bolt. For this to be effective you will need plenty of thread at both ends to tension the rein and the anchor needs to be not only deep but also against solid ground. It is not good enough to bury it with loose fill. You could concrete the anchor in the ground and tension from the wall side once the concrete is set, and then cut off the excess threaded rod. Make sure you have enough thread to do this.

    You could also go all concrete for the anchor, by drilling two 1/2" holes 4" apart in the angle and push two sections of 1/2" reo bar through them and concrete the lot. A beam that is 8"x8" 3' long with two 1/2" bar in it is plenty for an effective anchor.

  29. #29
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    The land is not flat on my side. I wish it was.
    Since I'm using the "T" columns and the concrete horizontal rails, can I construct a gabion that is less than 3 ft. deep? Say, 1.5 or 2ft.? So, 3ft. tall 8 ft. wide and 1.5 ft. deep? The gabion would be right up against new wall.

    What about the stock thickness for the "T" columns? I'm wondering if I could get away with less than a 1/4 inch. I'm concerned about the weight of these and maneuvering them into place.

    Also, how can I cut the existing ends of the wall in a straight line? The wall is 8 to 10 inches thick and would require a very large concrete saw which would be difficult to operate on a slope. Perhaps a small demo hammer with a careful touch?

    I'm going to draw a rein-back anchor plan just to make sure I understand what you have in mind.

  30. #30
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    You can probably get away with a 2' deep gabion, but that would mean more strain on the reins.
    Thickness of the steel. Hard to say. Probably a question for an engineer. Wouldn't go under 5mm. Not sure what you have available.

    To cut the concrete wall neatly in a straight line, I would use a 9" grinder with a diamond disk, and do a cut from each side. Best thing is to find a concrete cutter that does it for you. Those 9" grinders require some serious arms to go with. A petrol driven concrete saw with a water connection would do the job easy. You don't need to cut all the way through the 8 or 10". Once you are through 6" the rest can be broken off easy.
    However, a concrete saw is not an easy tool to use.

    I never had use for drawing software. What do you use to do yours?

    Looking at the profile you have chose for the columns, yours is an asymmetrical 12"x6" ... Are you going that wide just to cover an irregular cut in the concrete? Cut it straight and you can use 8" wide with the web in the center. You can even go deeper with the web and have a stronger column.
    Say 8"x8". Can you get them Hot Deep Galvanised?

  31. #31
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    I've got a 9 inch grinder, so I'll try that.

    I use Photoshop. I know it well, so it's my planning tool.

    OK, 8x8 "T" column. I'll have to call around about galvanized.

    Attached is a drawing for the rein back.

    Thanks again Marc. You are a big help.

    Attached Thumbnails Attached Thumbnails rein_back.jpg  

  32. #32
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    The rein will need to be much longer and going down into more solid ground. I would place the anchor 3 feet deep and 10 feet away from the wall.
    Also the anchor itself is horizontal not vertical and the rein attaches in the center of the member be it concrete or steel.

  33. #33
    Golden Member
    Join Date
    Oct 2017
    Location
    Melbourne - Yarra Ranges
    Posts
    682

    Default

    ...obviously difficult to provide advice here behind the desk on the other side of the planet as your local soil conditions and what works in your local area is unknown....which is why some will rightly say you need engineering advice.

    If it were me, I'd choose one or the other with consideration on the above statement .
    If designed right based on your local conditions, you should only need one solution...but hey thats the big unknown and where Marc is coming from to get a good result. Either way you may go to a lot of trouble to "fix" this section only to have another fail at some point if the original wall wasn't designed correctly.

    For me I'd use C section and slot 75mm (1.5") thick x 200mm (8') sleepers x 4 sleepers high of your choice with good drainage behind and as deep as you can get them 3 to 4 feet min. Depth and width of hole is governed by your soil conditions and you will likely get a better result if you have a square hole rather than round with better bearing pressure against a flat side rather then a 1/2 circle. The width of the hole required is also unknown based on your local conditions.

    Place the posts either side of the broken wall. Sleeper length - standard 2m (6.5') here but dont know your local standards. No cutting of the concrete wall required.
    If sleepers are concrete, allow 20mm extra between the inside of the steel. If wood, than simply cut to length if your slightly out setting your steel posts in concrete

    With the gabion, in your sketch there is a fence post behind it. Digging too much out will undermine your fence post integrity and you will need to take this into consideration. There doesnt look to be a lot of distance between the fence post and back of existing wall.....another reason why sitting behind the desk here I'd suggest the "C" section route

  34. #34
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    I agree Bart.
    A few considerations:
    Yes, the repair may be a lot of effort only to fail elsewhere, but such is the nature of repairing vs rebuilding. The cost of rebuilding the lot would be substantial.

    Because of the soft nature of the soil in question, according to the OP, I would try to add as much mass as possible to plug the failed section, ergo the idea of a gabion. A gabion that is 3' wide and 3' high the length of the hole, is self supporting and would not need anything else. The concrete slabs seem to be required purely for visual effect.

    The steel post I suggest, complete with reins and anchoring, are there to hold the wall back since it has lost continuity. The obvious alternative would be a gabion build on the outside a couple of feet longer at each side of the opening, inside the neighbour's property, but I doubt the neighbour would like this.

    Your C channels and concrete slabs are also a perfectly good alternative, providing the channels are tied back in a similar fashion and keep the existing wall vertical.
    Many ways to skin a cat. Yes, not easy to guide someone in another country when we don't even know what materials are available.
    However ... it's not rocket science, really just a small job.

    It would be interesting to know how legislation works in your state Worrel. In NSW, the responsibility of a retaining wall is with the person that dug the landscape and made the wall necessary. Usually the person below, that is your neighbour. other states within Australia have different ideas, I wonder how it sits in your case. Also ... usually covered by insurance under water damage.

  35. #35
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    In America, there are no protections; you are on your own. Sink or swim.

    Insurance does not cover this.

    I'm still not clear on the rein-back. Is the 10 footer bolted to the top of the "T" column and then angles down at least 3 ft. to the opposite end where it is bolted to a horizontal concrete beam. Do I connect both of the rein-backs from each of the "T" columns to this concrete beam?

    Thanks Marc.

  36. #36
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Thanks for your input Bart. It's nice to know you're checking in on this thread.

  37. #37
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    Correct. The rein goes from the top of the column to the center of a horizontal member that is in the ground 10 feet behind the wall. Think of it like a T where the top of the T is the concrete or steel section in the ground, and the leg of the T is the rein that goes to the top of the column.

    What you need is to tie back the column making it impossible or very difficult to fail. If the column is done the usual way, the soil behind the wall, loaded with water shifts forward slowly and eventually topples the wall. The post if only concreted in the ground, has a lot of leverage and the only thing stopping it from going forward is the front of the footing against the ground below. With soft ground, this is easy to achieve. That is what Bart refers to when he says to make the footing square not round. A better front against the ground.
    With the anchor buried in a horizontal plane, and laying parallel to the wall, the anchor is facing solid undisturbed ground when the rein pulls.
    Each rein has it's own anchor, you don't need to make a giant trench for both.

    From your last sketch of the anchor, all you need to change is the distance going back into your property, so to be away from the wall 10 feet, and then turn the anchor around from the vertical position to horizontal and parallel to the wall.
    I understand that it will be a lot of digging, a small trench for the rein and then a deeper for the anchor. You be the judge of the soil you encounter as you dig. If you find that 10 feet back and 2' down the soil is solid, you can have the anchor there. If it is still soft, may be 3' is what is needed for the anchor to have a good hold and keep the top of the column firmly in place.

    When I was 15 ... more than half a century ago ... we built a lot of retaining walls to keep river banks from being washed away. In those days we used hardwood planks, jetting them into the river bed, and 3 hardwood beams, one at the bottom, one in the center and one at the top of the hardwood planks. Sometimes only two where required. The boards where 5' into the mud and 5' above, but all that kept them in place were reins of one inch round steel as far back as practical, into a hardwood anchor usually half a hardwood sleeper, and buried horizontal in the ground with the large face, facing the ground.

  38. #38
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    OK, I've revised the sketch. I think I understand it now.

    I enjoyed the bit of your personal history. Sounds like a whole lot of hardwood. Oak soaked in creosote? 10 footers must have been very heavy.
    Attached Thumbnails Attached Thumbnails rein_back_2.jpg  

  39. #39
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    Yes, that is good. You actually don't need to do an anchor that long spanning the whole opening for both reins. You can have two separate anchors one for each rein, about 2' each and with the rein in the center of the anchor. Of course a long concrete beam spanning the distance between both reins would be better, only much more work.
    The boards we used were Ipe, very heavy. Steel, plastic or rocks, is the choice today.
    Tidewall - Manufacturer of Vinyl Seawall, Vinyl Sheet Piling and Vinyl Seawalls

    THe picture below shows how the wall is anchored.

    http://www.tidewall.com/applications...ntilevered.pdf

    Attached Files Attached Files

  40. #40
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Hey Marc,
    Thanks for the info. I've heard of Ipe, but never worked with it. I'm amazed that vinyl and steel can accomplish the same thing.
    I don't quit understand the cantilevered, single wale, wall. It looks like a rein-back, but there's no anchor. What is holding that brace in place? It looks inadequate.

  41. #41
    Deactivated User Marc's Avatar
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    13,859

    Default

    That is a river bank and what you see is the river wall. The vinyl sheets are pushed in the river/sea bed half way and have a hardwood beam at the top edge. The sheets of vinyl are held back by a rein that is fixed to a short stump deep in the ground. You can see the anchor at the end of the rein.

    That is all that is needed to hold the steel rod back. There is something from that stump going down i frankly don't know what it is. It is possible that the structure is built before filling behind the wall and so the anchor needs a rod to keep it in place before it is all filled in, to prevent the excavator moving it out of place.. (?)
    That is one of the best sea wall you can get, better even than steel if done properly. Only large stone boulders can beat that type of sea wall.

  42. #42
    Novice
    Join Date
    Feb 2021
    Location
    californiia
    Posts
    22

    Default

    Thanks for the explanation Marc.
    I would also like to thank you for all the help you've been. Your wealth of knowledge and your generosity are greatly appreciated. I have so much more information now to make informed decisions about my approach to building this wall. You do a great job of giving adviCe.
    Sincerely,
    -worrell

Similar Threads

  1. concrete retainer wall footing
    By Greenie in forum Retaining Walls
    Replies: 1
    Last Post: 22nd Sep 2010, 12:01 PM
  2. Do i have to use AG behind my retainer wall
    By oohsam in forum Retaining Walls
    Replies: 7
    Last Post: 23rd Nov 2008, 10:25 AM
  3. Do i have to use AG behind my retainer wall
    By oohsam in forum Landscaping, Gardening & Outdoors
    Replies: 7
    Last Post: 23rd Nov 2008, 10:25 AM
  4. Retainer wall
    By Chumley in forum Retaining Walls
    Replies: 6
    Last Post: 5th Nov 2008, 05:19 PM
  5. Retainer wall
    By Chumley in forum Landscaping, Gardening & Outdoors
    Replies: 6
    Last Post: 5th Nov 2008, 05:19 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •