Block wall falling
Block wall falling
(OP)
Hello everyone,
I would like to get your onion and help on this matter. I am being asked to fix this problem which is not my specialty.
A storage building made of 2' x 2' x 6' concrete blocks stack on top of each other and a fabric enclosure sat on top.
The wall is made of four course and there is no reinforcement.
The only sit on very small keys along the blocks.
The back wall is becoming mis-aligned and the top blocks overturning.
The owner has put some steel bracing and seems is not solving the problem
I don't know where to start, to me is not a solid gravity wall because is not one piece but stack of loose blocks
What the solution and direction appreciated
Any reference - sample old calcs?
I would like to get your onion and help on this matter. I am being asked to fix this problem which is not my specialty.
A storage building made of 2' x 2' x 6' concrete blocks stack on top of each other and a fabric enclosure sat on top.
The wall is made of four course and there is no reinforcement.
The only sit on very small keys along the blocks.
The back wall is becoming mis-aligned and the top blocks overturning.
The owner has put some steel bracing and seems is not solving the problem
I don't know where to start, to me is not a solid gravity wall because is not one piece but stack of loose blocks
What the solution and direction appreciated
Any reference - sample old calcs?





RE: Block wall falling
You have to check for sliding at each block course. I would likely be neglecting the keys (depending on how small is small) and designing around that.
What is being stored in this enclosure?
RE: Block wall falling
The first thing to do is recognize that the "structure" is not suitable for an engineer to analyze and give a clean, short and terse report that has any real authority.
Possibly more information on the future use would shed some light on the question.
It is probably just a building that was built using some available materials and methods. - the "roof" probably of tubing and a fabric offers no stability and questionable transfer of vertical and horizontal loads. - It seems it is just a gravity wall with a temporary weather enclosure added.
The basic concept of using massive, heavy concrete or stone block has been used for decades on many more substantial buildings. There are thousands of 4 to 7 story buildings (apartment and office) performing well in eastern Europe that are over 50 years old that were built on a foundation of 1Mx1Mx2M cast concrete blocks with no keys, no mortar or locking mechanism for shear resistance. There were no poured in place concrete footings because of available products and performance of previous structures, so bedding on soil was shown to be adequate. - Gravity and shear friction are very useful.
It seems that the portion of the structure has problems that are applying some lateral loads through the years that come and go and change with the season.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Block wall falling
RE: Block wall falling
RE: Block wall falling
The material stored is gypsum for people asked me what's the material.
For people who say this problem was mentioned by others or past threads please refer me to those threads. It's easy to just say well in past this issue was stated.
If I did not need your opinion and if I knew the solution I would not post it here.
To me this is not a typical retaining wall situation that's why I am asking for help and opinions not interrogation.
I am hoping a skillful senior engineer that have encountered in his work experience in past and he is well above competition and hiding the techniques respond and help a less experienced engineer.
Thank you all ones that sincerely wanted to help and direct me.
RE: Block wall falling
Soil movement as noted by emmgjld but you say it's on a 12" thick slab so that's unlikely.
Or
The loader operators don't know how to drive properly. The 30psf wind (stab in the dark but likely a reasonable assumption) would not cause the extent of movement shown.
RE: Block wall falling
RE: Block wall falling
http://www.eng-tips.com/viewthread.cfm?qid=381696
Referring to "bulldozers" when you probably meant "loaders".
RE: Block wall falling
Your earlier thread, as you would know, is this one:
thread507-381696: Wall for impact of Dozers
You asked for opinions, and mine is that this type wall is not suitable for the application, and needs to be replaced with a wall which is designed for the forces which will be experienced.
RE: Block wall falling
By the way, most of those here review many different "rooms" and so double posting is not needed.
RE: Block wall falling
The owner is seeking to repair or reinforce not to re-build, this to who commented rebuild the structure.
Is there any way we could reinforce the existing wall beside laying blocks behind?
What is a proof of even laying blocks behind is adequate? Where shall I start in crunching numbers?
How do I proof that your solution on laying blocks behind with that amount will fix the problem?
RE: Block wall falling
Use that load information to design the piling and the planking as well as finding the depth of H-pile penetration needed. You may need a geotech engineer to provide data for that design also.
Once the H piles have been driven and the planking installed, fill the opening between the old wall and the new wall with a low compressibility material, such as a low cement content concrete, or at least a well graded sand and gravel, tamped in.
If you don't care how the job looks, drive the piling next to the wall at say a 5 ft,. spacing and place blocking between the H piles (or what other pile you use) and the old wall. You still need to know all the load and soil data to do it right.
I really doubt that, leaving the old wall there, or somehow "making it internally stronger" will do the job.
Of course making sure the operator of that machine does not do any pushing of the wall also will work. That can be done by having him use his bucket to drag the excess material from the wall out into the open and doing his loading by driving parallel to the wall. For back dragging, the bucket should be in full dump position.
Just thought of another solution, but again costly. Set a quarry drill on top of the wall and drill holes all the way down through all concrete and into the earth. Spacing probably about 5 feet along the walls may be needed. Install tie-rods that are grouted into the earth below, making this a wall reinforced against bending in the planes perpendicular to the floor. If the floor is sufficiently strong you may even grout the rods to that floor, but somewhat questionable. All of these rods will best work if they are pre-loaded to provide a compression into the blocks (post stressing). You also need the horizontal loads from the stored material and the pushing machine to approximately design this system. With any fix, a design based on known loadings is the best way to be sure it will work.
RE: Block wall falling
RE: Block wall falling
I like the idea of pile and planking but try to picture it as u explained.
Would u mind kindly draw a sketch - maybe 3D showing the piles and the blocks and the planking?
Thank you
RE: Block wall falling
Is a sketch really required?
RE: Block wall falling
On the proof that the extra row of blocks will do the job, well, with the loading data and the weight of the blocks you can design the wall so that it won't tip over, because of gravity holding it there, assuming you mortar all the blocks together (making it a very heavy unit). You also may have to add dowels into the slab to create more resistance to sliding on the slab. This idea also takes into account the length of the wall, as one solid thing, not separate things. If you want to be more sure of that, add mesh steel reinforcing between each layer of blocks, designed as a horizontal beam.
With the loader on site, it would seem that all work can be done by current staff and that machine.
Let's suppose two rows of stacked blocks is not enough, of course one can add another one, but interlock all together as one unit. Seeing the current wall stood up pretty well with no special mortar or attempt to provide more over turning resisance, I'd think what I've proposed will check out fine with some rough calculations and maybe the dowels into the slab.
RE: Block wall falling
Thank you very much. I greatly appreciate it.
A very elementary question - the new blocks that we are gonna stack up behind the existing wall, they don't need to be same as blocks in the existing wall (I mean same type???
The blocks in the existing wall are V-lock blocks which the key runs in the length direction and I dont know when we place them perpendicular if they just can be sat on top the key of the bottom ones???
Do you know some relaible block manufacturers?
Thank you very much
RE: Block wall falling
Thank you very much. I greatly appreciate it.
A very elementary question - the new blocks that we are gonna stack up behind the existing wall, they don't need to be same as blocks in the existing wall (I mean same type???
The blocks in the existing wall are V-lock blocks which the key runs in the length direction and I dont know when we place them perpendicular if they just can be sat on top the key of the bottom ones???
Do you know some relaible block manufacturers?
Thank you very much
RE: Block wall falling
Then, the original blocks must have come from some supplier locally. In the USA these are found at ready-mix concrete plants, made from the left-over concrete that was not needed at the job sites. That's why they cost less than manufactured blocks.
Next, in that one edge may have the "v" projecting out and that may be in the way of what is planned, you get the strongest guy on the job with a sledge hammer and knock that projection off. Some sawing with a hand held saw may help. For some orientations, you place the "V" notch and projections on their sides, not top and bottom, especially for the layers 2, 4, 6.
Adding the grout or concrete between layers and between adjacent blocks binds them all together. When you do this make sure the blocks are not dirty, BUT are not wetted either. The grout then will bond much better to the dry surfaced blocks.
Give this project to a person in charge who has some "know how" and can work with what is presented and understands the goal.
I may have taken the wrong slant on evaluating your comments and questions, but is there an experienced contractor in your area that can be hired with the known background experience in varied jobs? In finding such a contractor, I'd print out all these questions and answers and ask if they understand and can point to other work where they have had to do some thinking on their own to carry out a job where it had not been done before and still came out properly? It may be just one person, but with the ability to direct on-site personnel. This really is a simple job, but any job can be done wrong by the wrong person.
RE: Block wall falling
Again me, I've been questioned that what is the benifit of laying blocks behind existing wall in the second layer parallel to wall?
Why not all blocks in all lawyers run same direction (which is perpendicular to wall)?
I appreciate provising a reason for this idea proposed by you.
Thank you
RE: Block wall falling
RE: Block wall falling
If they are loose on top of each othe the 90 degrees will not be effective, rigth?
Thank so much and also this project is in U.S.
RE: Block wall falling
As to the blocks, stop in a any ready mix plant and look around. Likely they have them stacked somewhat and you can see what is available. My experience with them is they are remarkably strong, even made from reject concrete at times. One project could could not have met budget if it were not for their lower cost than fancy manufactured blocks. Some landscaper material suppliers (stone, bark, etc) use them for retaining the products, but they don't have loaders doing damage.
RE: Block wall falling
Thank you very much for all your kind and expert assistance.
I greatly appreciate it.
Also I really did not mean to insult anybody by posting the question in Geotech forum. I just was trying to get Geotech people opinion.
Again thank you very much.
Respectfully,
SKJ25POL (Structural)
RE: Block wall falling
This alternative is assuming you are using a cement - sand grout between all members, horizontal and vertical, and you build a double thick wall, one behind the other. However, it will be necessary to tear down the present wall so that every course will have a layer of high strength geogrid laid between blocks. That grid purpose would be to tie the two walls together to create that one solid "block" of concrete. The projections and indents in the blocks will help anchor that grid also.
Do not substitute a commercial mortar mix for the cement-sand grout. They usually contain fillers and the bond strength of those mortars is way below that of a cement-sand grout.
This alternative would be easier to build and the grid tends to tighten up as the blocks are laid on it, stretching over those projections.
A stability calculation still is required to be sure it works and setting details, such as dowels in the slab.
RE: Block wall falling
My boss suggesting me to use some wear steel plates against back wall (inside) attached to wall do u know by chance what is common industry practice for these plates? What type of steel? How thick? and how to attached it to the block wall?
What are possible problems?
I did not want to post a new ad but I really cant find any information off internet.
Thank you
RE: Block wall falling
If I were in your shoes having an owner that has his own ideas on how to fix the problem, but does not want to "do it right" so it works for years to come, I'd say "good bye" and chalk up the time spent as another experience to fade into memory. Now and then we have to bite the bullet and walk away.
From my point of view, if there were other members here with different ideas that would work, you would hear about them.
RE: Block wall falling
An 8' high gravity wall with heavy equipment operating in the area under little supervision could be a red flag. There is little reasonable documented information on the performance, probably because no one expected it to be used permanently.
We had 8 similar bunkers made from 12" reinforce block or reinforced concrete. There very often accessed by a big front end loader at night(24/7 operation) and never had a real problem. They were only 6' high because we wanted the "peak" of the aggregate to be less than 8' for safety and OSHA possible problems.
Just a different slant.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Block wall falling
www.PeirceEngineering.com
RE: Block wall falling
The steel plate on inside wall is intended being added in addition to laying blocks on the outside of wall.
The peupose of the paltes are to minimize concrete chip and scraping by the loader's blade.
Dont know what's the practical size of that plate (thickness) and the type of steel plate (structural or scrap steel)?
Any body has a sample photo to show a actual one.
Thank you
RE: Block wall falling
RE: Block wall falling
Is it possible to mortar the 2 x 2 x 6 blocks?
What about gluing them? What are typical practical common glues? Brand name?
This is for the option of setting blocks behind wall, just to stablize them better.
Thank for any direction
RE: Block wall falling
RE: Block wall falling
www.PeirceEngineering.com
RE: Block wall falling
The block manufacturer tells me due to weigth of blocks the mortar between will seep from joints?
Also I am not talking about between existing wall and pile of blocks, I am trying to bond the layers you draw a stecth for.
RE: Block wall falling
RE: Block wall falling