Hey Y’all,
I need to poke some holes in the ground 2′ diameter and 19′ deep, and then I need to fill the holes with concrete up to the 10′ line.
This needs to go fairly quickly and the level of the concrete from hole to hole needs to be within an inch or two of the same across 7 holes on 6′ centers.
It is highly unlikely that a person could see down this hole once the steel is in.
If nothing else I can measure the volume it as it goes into the hole but I really want to avoid that.
Any idea how to reliably check the level of the concrete as it is being placed?
A king can stand people fighting but he can’t last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Replies
The idea is for all the concrete to be the same level, more or less? Laser level, level string, builder's level? Shoot the holes and install grade stakes? Am I misreading the problem?
Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
That's correct -- the concrete needs to be at the same level and that level is referenced to a benchmark.Problem is that this level is 9' below grade, down a 2' diameter hole that has 8" wide-flange in the hole and a collar probably made of 2x4s. I suppose I could put a big foot on the levelling rod for the laser, that way it would float in the concrete and I could feel the top of it. I'd want to be pretty sure of this, though. Not enough concrete and we could have a pretty serious life safety problem. Too much concrete and my world is going to turn into wet sh!t.What's happening here is we're poking the holes, placing the 20' section of wide-flange, placing the concrete, then as we excavate down we weld a piece of C-channel horizontally to the wide-flange with every 8 inch increment that we dig to shore the face as we go down. When it's all done we have a 9' vertical face of steel.The concrete needs to be at the same level because this is seriously Type C soil. When I get to the bottom of this excavation there is going to be some amount of pressure at the foot of this wall and if the tops of the piers don't line up I won't be able to weld the last piece of horizontal C-channel in. At that point it would suck to be me.I guess I could also grease the steel above the 10' line so I could hammer the concrete back off if I do over-pour but I really don't want to be in that hole with a hammer.Good idea. Thanks.Any more ideas?A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Is this a temporary or permanent wall?If you're casing the hole, how will you get to the wide-flange to weld to it?Seems to me the simpler approach would be to case it with steel, drop the beam down the hole (or a rebar cage might do), pour concrete to the top, and then weld to the steel casing. If necessary some sort of collar could be fitted to the casing at the weld points to distribute the force and assure a sound connection.
If ignorance is bliss why aren't more people
happy?
<<Seems to me the simpler approach would be to case it with steel, drop the beam down the hole (or a rebar cage might do), pour concrete to the top, and then weld to the steel casing. If necessary some sort of collar could be fitted to the casing at the weld points to distribute the force and assure a sound connection.>>Man, THIS is why I hang out around here.Are you an engineer?[edit -add this line.] It's a permanent wall.I'm working from engineered drawings and everything about this job is bothering me. I don't mind the work a bit, but there are a lot of unanswered questions between the drawing on my desk right now and the eventuality of being in the hole with welding leads and a few hundred tons of Type C above me.I really like your idea. Several great points. If we use steel casing with a rebar cage we can get away from the wide flange. That stuff is over $10 per foot. We can also work enormously faster. If the hole is drilled plumb, then the casing is plumb and I can quit trying to figure out how to get the faces of all this wide flange to line up in 3-D. The concrete will take no time at all, we're then just filling a hole.The only thing I haven't gotten my head around yet is welding the C-channel to the casing. That is, getting a surface that I can get enough contact and weld to trust my life to.Any ideas?A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Edited 2/2/2006 11:50 am by Catskinner
> Are you an engineer?Well, yes. But I only work with electrons and ones and zeros.Re welding the C-channel, I haven't quite visualized how this is all going together, but a few possibilities come to mind:1. Weld a length (maybe you could do 16" at a time) of steel channel (something like 6" wide and 3" deep) vertically to the casing, with the open face of the channel facing the casing. This would give you two long contact points for the weld, and then you could weld your channel to this channel.2. Have a shop bend up some steel collars that you'd work around the casing, then weld to flanges on the collars.3. Forget about welding. Run cable or rod around the casing and bolt it to the C-channel.Of course, if you could somehow manage to put the C-channel behind the casing rather than in front of it then there would be some extra safety margin (though welding would be more difficult).Of course, another option that might be worth considering is a slurry wall such as those they used for the Boston "big dig". Probably more expensive, but maybe not, since I gather they can be done in a semi-automatic fashion.
If ignorance is bliss why aren't more people
happy?
<<> Are you an engineer?Well, yes. But I only work with electrons and ones and zeros.>>So you'll appreciate my friend's observation (he's an EE) that there are only 10 kinds of people in the world; those who understand binary and those who don't. <G><<Re welding the C-channel, I haven't quite visualized how this is all going together, but a few possibilities come to mind:1. Weld a length (maybe you could do 16" at a time) of steel channel (something like 6" wide and 3" deep) vertically to the casing, with the open face of the channel facing the casing. This would give you two long contact points for the weld, and then you could weld your channel to this channel.>>That might work.The situation as it exists is we have a building with a shallow foundation on really bad soil, Sheet piling is out of the question.We need to get 7 feet below the existing building footing, right up against it.The vertical component of the shoring is this wide flange, the restraint is provided by the 10' embedded in the concrete.The retention is provided by these 8" C-channels that we install from the top down as we go.The idea is we put the verticals in and weld another 8" horizontal c-channel to that with every 8" we dig down. We dig up to the face of the verticals and no more, so cable or collars are out because there needs to be dirt beyond the face or the existing building is gonna fall on us.On the basis of your comments I am thinking that if I clipped the flange of the C-channel at a 45 I would not compromise the strength and could probably get plenty of contact on the vertical pass.Thanks. I think that's going to work.That having been said, all other ideas are still welcome. A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Is this temporary or permanent shoring?
If you go DanH's way - I'd look into just driving the casing and no concrete backfill. vibratory hammer. I also think you could boom down considerably on your casing size-- it sounds like you got engineering support.
If this a temporary build, I would suggest steel sheet piles- vibrate them in and out.
If your engineer is stuck on the original plan - I would suggest
1. Weld a aprox.2'D flange on the wide flange at your -10 elev.
2. weld a 2.5" - 3" NPT collar or thread-o-lette on the flange.
3. Burn a couple of 1" vent holes in the flange
4. Use a 15' stick of 2.5" - 3" pipe to adapt to the pumper truck's output.
5. you should be able to watch the pour-vents and know when enough is enough.
6. reuse your 15' pipe for next hole.
7. a second piece of 3" pipe may be used in place of your vents to bring the return to the surface. Just watch out for the Hyd. effect of the conc. trying to push your 8" beam up.
Keep us posted on your method and success
Boats, that is too cool.This is why I hang out here. You guys are amazing.As I was telling Dan, the sheet piling is out of the question.You're right about the engineering assistance. I bet that casing could be a whole bunch smaller (what, maybe 12"?) if there were three pieces of #5 grade 60 with #3 stirrups inside it and we pumped a 3/8-minus grout.What do you think?A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Why bother drilling and casing? Get 40' pieces of H-pile and use a vibratory rig to drive them as your soldier beams. You'll have 30' of embedment to overcome the 10' of soil surcharge you're going to create when you excavate. Then use either timbers or precast concrete sections slipped between (or behind) the soldier beams to retain the soil.
Obviously you need to get the engineer to re-size everything, but it sounds like he did a pretty half-azzed job with what he designed already- it seems like no one looked at the constructability of the design. Not to be harsh, but you may also want to seriously re-consider doing this job yourself- sheeting and shoring for an excavation like this isn't something you want to "experiment" with- especially when people are going to be working in the hole you're about to create. I'd get a local underpinning and foundation company involved that knows what they're doing- they'll probably get a chuckle out of the design you have.
Bob
<<Why bother drilling and casing? Get 40' pieces of H-pile and use a vibratory rig to drive them as your soldier beams. You'll have 30' of embedment to overcome the 10' of soil surcharge you're going to create when you excavate. Then use either timbers or precast concrete sections slipped between (or behind) the soldier beams to retain the soil. >>If we could have done that, we'd be done already. There would be nothing left of the existing building if we tried that.<<Obviously you need to get the engineer to re-size everything, but it sounds like he did a pretty half-azzed job with what he designed already- it seems like no one looked at the constructability of the design.>>That's why I came here to you guys. I've already used up all of the ideas that the GC, the architect, and the engineer had, and I didn't like any of them. <<Not to be harsh, but you may also want to seriously re-consider doing this job yourself- sheeting and shoring for an excavation like this isn't something you want to "experiment" with- especially when people are going to be working in the hole you're about to create. I'd get a local underpinning and foundation company involved that knows what they're doing- they'll probably get a chuckle out of the design you have.>>More presumptuous than harsh, I'd say. I've spent enough time in the bottom of a hole to be comfortable with this type of work. I've done excavation inside shoring, set the shoring, placed the structural components, and under a lot worse conditions than this. I've just never seen anything quite like the drawing I have sitting in front of me right now (with a PE stamp on it no less).We've already done all the chuckling we're going to do. Now we need to get a hole in the ground and not kill anyone or pull the existing building over.That is to say, "Git-R-Done". <G>So what's going to happen here, as it usually does, is I am going to take the idea I like to the engineer I usually work with and get it stamped. I've never worked with this guy before, the GC chose him.And thanks to the good folks at Breaktime, I now have an idea that I like.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Whatever you do, keep us informed. I kinda want to know how this all works out. (And take a few pictures for us.)
If ignorance is bliss why aren't more people
happy?
<<Whatever you do, keep us informed. I kinda want to know how this all works out. (And take a few pictures for us.)>>You bet I will. I've got a digital camera, I just need to learn how to post photos here.Thanks again for your help. I really appreciate it.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
More presumptuous than harsh, I'd say.
Didn't mean it that way at all. It's difficult sometimes to get a sense over the internet of how someone intends a posted question to be taken. Based on my read of your original post and early responses, my take was that you may be in over your head, so I merely suggested that you may want to investigate having someone else take a look at doing the work. Obviously that wasn't the case- my bad.
As a last suggestion, have you looked into pre-augering and then driving H-piles? Sometimes you can get enough of the soil loosened up that you won't have to vibrate the piles in (you almost "push" them into the loosened soil), and won't damage the adjacent structure. It may save you from the situation you're in currently.
Bob
<<Didn't mean it that way at all. It's difficult sometimes to get a sense over the internet of how someone intends a posted question to be taken. Based on my read of your original post and early responses, my take was that you may be in over your head, so I merely suggested that you may want to investigate having someone else take a look at doing the work. Obviously that wasn't the case- my bad.>>No offense taken then. Thanks.<<As a last suggestion, have you looked into pre-augering and then driving H-piles? Sometimes you can get enough of the soil loosened up that you won't have to vibrate the piles in (you almost "push" them into the loosened soil), and won't damage the adjacent structure. It may save you from the situation you're in currently.>>I've been thinking about that, too. I did one of those last summer where the soil was softer and the load was lower. Augered down about 5', dropped 15' pieces of drill stem in the holes, and drove them in flush. Worked great.As for this site, depending upon the soil conditions, that might work. I think the engineer is concernes about restraint in these poorly graded soils. I've still not seen the soils report (I don't know why). The GC had geotechnical and structutal engineers on this one already. Rumor has it that the first 10' or 12' are Type C, and then there is a really tight substrate. I need to look at the report and see what is actually there. I'd like to see the cores, but that may not be possible.If it's all poorly graded Type C we could probably do as you suggest as long as the flange offered enough face. Hammering is going to be a no-no unless we are gentle. If the subgrade is tighter than we think at some depth or if we have big cobble down there then the risk of damage to the existing structure is too high.As we're thinking out loud together here, it occurs to me to call one of the folks who do the potholing with high-pressure water and a vacuum. I don't know how deep those guys can go but if they could give me a real small hole (just enough for a relief) then your idea would work really well. I could probably more or less push the wide-flange in.I'm continually amazed by what gets handed off as engineering.Almost as amazed at the amount of time and money that goes into a project before any of these design professionals think to ask the guy who's going to do the work what he thinks.Come to think of it, they never did ask. They just faxed me the drawing and asked for a price and a start date. I was the one who had to break it to them.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Come to think of it, they never did ask. They just faxed me the drawing and asked for a price and a start date. I was the one who had to break it to them
I just hope you didn't give them the price yet ;)
The waterjetting might not be a bad idea either- it'll probably depend on what type of soil you've got down below the Type C. If it's too soft, it'll wash out too quickly.
Bob
<<I just hope you didn't give them the price yet ;)>>Not yet -- I thought I'd do it in person so we could be sure and have the smelling salts on hand. <G><<The waterjetting might not be a bad idea either- it'll probably depend on what type of soil you've got down below the Type C. If it's too soft, it'll wash out too quickly.>>The longer I sit here and think about it, the more I think you're right, the water jetting yould make a mess.I just called a friend of mine who spent over 20 years on the rigs in the Saudi and on the Gulf of Mexico. He suggested driving the well casing and jetting the dirt out once the casing was in. I explained the problem with any vibration and the existing building. So he said a good mud engineer could design a mix that would hold the native material long enough to get the casing into a drilled hole.He said we'd have about 7/16" clearance between the casing and the mud sleeve when we were done. I think that's acceptable.As for welding the channel to the casing, it seems to me that a vertical pass between the channel and the casing ought to hold. If a good 1/8" x 8" bead won't hold it, I don't need to be down there and neither does anyone else. I couldn't get any direction out of the engineer (?) so I'm thinking a 6010 root pass on each end where the two channels meet and a pass with 7014 over it. The 6010 freezes quickly and is easy to work with in such conditions. The 7014 is a very fast rod and gives a real nice appearance, and will provide enough thickness at the joint that I won't ever have to think about it again.Thanks again for the help. I certainly do appreciate it.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
> So he said a good mud engineer could design a mix that would hold the
> native material long enough to get the casing into a drilled hole.If they can do that, they can probably pour concrete directly into the hole, displacing the mud.
If ignorance is bliss why aren't more people
happy?
> As we're thinking out loud together here, it occurs to me to call one
> of the folks who do the potholing with high-pressure water and a
> vacuum.That essentially what the slurry wall is, only the slurry wall goes a couple of steps farther. The hole is drilled with water and maybe some mechanical assistance, and as it's drilled the hole is backfilled with slurry (like oil well mud) to withstand the soil pressure. You can dig out an entire wall this way, set steel, then pump in concrete, pushing out the slurry.
If ignorance is bliss why aren't more people
happy?
easy- measure the hole at reguired dept to elevation, figure how much concrete is needed, measure with a five gallon bucket, pour in hole.. 2+3=7
It won't happen on this job, but that is something I need to learn about. I'm sure it could be useful. Maybe I need to do some web searches later.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
That's how the "bathtub" foundation of the old World Trade Center was done, a slurry trench wall 70 ft. deep all around the whole complex. It shows up on those Discovery/TLC/History cable channels from time to time.
-- J.S.
I really get a sense of how nervous you are about being buried. please be very careful. have a bunch of contingencies ready.
Not nervous, just realistic.If I get buried it just saves the VA some money on that budget they are trying so hard to cut. <G> If I get someone else buried then I'll probably feel kinda bad about it, so I try to avoid such things.As MSA used to say in their ads;Professionals do not take risks -- they minimize the hazards.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
I misread 10 ft. as 10 in. What's so hard about that? I could send my 12 year old out to take care of it. <G>
Yeah, 10 ft. is more challenging.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
That was good for a laugh.You probably thought I just finally got hit in the head one time too many. <G>A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Exactly how difficult will it be to see in the hole? If there is going to be some visibility, use a laser measuring tool and shoot down between the bars to get the dot on the top of the mud. You will need to keep the tool at the same level above every hole, which will take some rigging, and you will need to approach the final level carefully, since the tool takes a reading at a single moment in time, rather than adjusting as the measurement changes.
Good idea. Thanks.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
You probably thought I just finally got hit in the head one time too many.
Nah, I was just wondering if you'd sworn off caffeine. It was an early morning post.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
I'm curious as to how you're going to get 2' diameter holes to not collapse with only 4' of soil between them.
I'm also curious as to why the concrete has to be so precise if it's 10' below grade- who's ever going to see it? What's going to sit on top of it? Can that be trimmed for final height?
Bob
We're going to case the holes as we drill.See above for the rest of the answer. If not clear, I'll write more.
A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
You can FEEL the level. Make yourself up a stick about 15 feet long, with a mark at the 10-foot distance. Attach a disk of plywood or some such about 8" in diameter to the end. (Be sure it's well attached -- the concrete will have a lot of "suck".)
Or just a dipstick -- put a stick down to the ten-foot mark, then pull it up and see if the end has concrete on it. (Or down to the eleven-foot mark and pull it up to see if it has 12 inches of concrete on it.)
There are other more exotic possibilities -- optical sensors, sensors that would measure the weigh of the concrete, etc.
I am wondering why one would want to stop ten feet below the surface. And also how you're going to bore holes 19 feet deep.
happy?
Good idea, thank you.See my reply to Andy. If that doesn't explain enough I'll write more.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
<<I am wondering why one would want to stop ten feet below the surface. And also how you're going to bore holes 19 feet deep.>>We're stopping 10' below the surface because we need 9' of bare steel to weld 8" C-channel to as we dig down in 8" increments.This is vertical (cantilevered) shoring for excavation in granular soils next to an existing building. We're going 7' below the existing footings, and as close to the building as we can get. So we need 9' sticking up out if the proposed finished grade and 10' encased in concrete below the proposed finish grade.As for actually poking the holes in the ground, the only thing I need to know about that is the phone number for the guy with the drilling rig. <G>A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
not certain if this is what you're after but a "water" level would work almost perfectly.
get a transparent length of 1" surgical tubing...really cheap. fill it with h2o. fix one end to a "reference" mark and fill the level of the h20 to that mark...."so and so height above a particular place". next, take the other end to your hole and measure down from the level of the h2o in the tube. keep in mind that the level at the reference mark needs to be consistantly on that mark...so raise and lower the other end till that level is on the mark. as a result, no matter where you go, you can establish depth in relation to the mark.
i'd like to apologize for (painfully) obviously missing the point. no insult intended, of course you know how to get this sucker level.......got excited about helping is all.
hope it works out well
<<i'd like to apologize for (painfully) obviously missing the point. no insult intended, of course you know how to get this sucker level.......got excited about helping is all.hope it works out well>>No problem -- that's what makes this place so amazingly educational and fun is everybody's willingness to help. And I certainly appreciate your willingness to help every bit as much as anyone else's.I'll let everyone here know how this goes. I'm gona fax the ideas I just got here to the engineer right now.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
......and here goes!!!!!!!! i'm fitting my mouth to accept my foot again, have you thought about a laser measuring "tape"
craftsman has this for $35 bucks, measure the hole, measure as the concrete fills up.http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00948252000&subcat=Measuring+Toolsi really just come here for the quotes anyhow
Is that really laser, or is it sonic. The sonic ones are confused by anything nearby (like the casing).
If ignorance is bliss why aren't more people
happy?
it's either a laser or the name (Craftsman Laser Guided Measuring Tool) is really misleading.....someone should report them.can't trust anybody these days!
It is "laser guided" -- a laser projects a point of light to show you approximately what the sound wave will measure.
If ignorance is bliss why aren't more people
happy?
Actually a good idea. As you can see by the previous post, great minds think alike. <G>A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
> that's what makes this place so amazingly educational and fun is
> everybody's willingness to help.It's always more fun/interesting to help than it is to do the work we're supposed to be doing.
If ignorance is bliss why aren't more people
happy?
I've been a little concerned about that. <G> I justify the amount of time I spend here with you guys (rather than out in the field digging like I am supposed to be doing or maintenance on the trucks and tractors like I am supposed to be doing) by the increase in productivity and profitability that I realize from all of this education that you provide.Yeah, that's the ticket. <G>Now about all that time I spend in the Tavern . . .A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Don't want to get "skinned" for sidetracking the post but what about on going maintance and the cost of repainting?
<<Don't want to get "skinned" for sidetracking the post but what about on going maintance and the cost of repainting?>>
Yeah, I thought about that also when I heard that this retaining wall is going to permanent. --9' of steel plate--sounds high maintenance--might be backfilled after work is completed? dunno.
As Ed McMahon would have said;You are correct, sir.It's permanent, but it will eventually be buried.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
What are you actually trying to accomplish? You started with a specific question and then through a series of 45 or so posts it became apparent that the people you are depending on for engineering this project don't seem to know what they are doing!
How could you give advice about something like this if you don't know the soil details, the type and condition of the building next door and several other things that you may know but haven't posted here?
What are you going to do with the open side of this excavation?
What do you mean by "it will eventually be buried" ??
<<What are you actually trying to accomplish?>>As I described earlier, we need to excavate to 7' below an existing shallow foundation as close to the existing building as possible. <<You started with a specific question and then through a series of 45 or so posts it became apparent that the people you are depending on for engineering this project don't seem to know what they are doing!>>I think that they are probably pretty good engineers. I've never worked with them before, they were hired by the GC. If you look at it from the engineer's perspective, there was nothing wrong with the original design except for the price.I wanted to control costs on the job and was going over the job in my mind, looking for some way to do this for less money. At the very least, come up with some way to minimize expenses caused by my part of the work. The original design, as I described, called for wide-flange in concrete. While there was nothing technically wrong with the engineering, it would be time-consuming and involve a lot of materials. The installation had a few expensive considerations. That's why I posted the original question.<<How could you give advice about something like this if you don't know the soil details, the type and condition of the building next door and several other things that you may know but haven't posted here?>>Do you mean how could anyone else (i.e. Breaktimers) give technically accurate and specific advice? They can't, and I wasn't asking for it.<<What are you going to do with the open side of this excavation?>>We're putting in a full basement.<<What do you mean by "it will eventually be buried" ??>>Once the basement is in place and the basement walls are cured enough we'll backfill everything. The retention described here, as I said earlier, is to keep the existing house from joining me in the bottom of the hole.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
In other words you'll be acting like a surgeon and burying your mistakes. ;)
If ignorance is bliss why aren't more people
happy?
I knew you understood. <BG>A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Just something to think about. In liability terms. If the engineer put his stamp on a particular drawing that "he" designed and some one like yourself came along and changed the design on the construction, would you be liable if for some reason the project happened to fail in the future? Whether it was your fault or not? Some one would be looking for a head to drop. Unless of course the engineer put a stamp on the new and improved building techniques. Just thinking out loud.
Semper Fi
Edited 2/2/2006 10:19 pm ET by Jarhead
I thought he said he'd approach the engineer with his suggestions - presumably, to get his stamp on the revised plan. I have nothing to add to this thread, but I couldn't help myself despite! Its been an interesting one to follow!
I by all means have nothing to add. Except for ignorance. It was something that just came to mind. Thanks for pulling my head out of my arse. By the way how are the tumble weeds out in Bakersfield?
Semper Fi
I'll probably get "hung" but check out the "other" site - they recently had an article about putting a support structure under a beach house - pretty good article on the design consideration for putting concert piles under an existing structure - project you have seems pretty intense and expensive (regardless how much you look to control costs) Andy might be able to help direct you to the article
Are we talking about JLC here? Let me know where to look, I'll go check it out. Thanks.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
check this out - might be useful - pretty extreme From JLC
Replacing a Beach-House Foundation
October 2005 Similar Articles
By Jeff Moroso (10 Pages)
A modified mat slab saved this cottage from the sea. First 100 Words:
Replacing a Beach-House Foundation A modified mat saved this cottage from the sea Jeff Moroso Recently, our company was hired to remodel a 1950s beach cottage just south of San Francisco. The job included repairing the house's seriously damaged foundation (see Figure 1, next page). Our original plan was to shore up the building, replace the support beams, and reuse the existing wood piles. But once we got the house supported by cribbing and temporary steel beams (Figure 2, page 3) and started excavating around the piles, we found that they extended only 4 or 5 feet below grade rather
No doubt about it, you are correct. I do not under any circumstance deviate from an engineer's directive once I have agreed to execute that design.But we haven't gotten to that point yet. I haven't agreed to anything, and for sure won't agree to either of the designs I've seen so far.Typically I will fight with engineers until I get something that I like, that is, I know it is safe, reliable, minimally objectionable to build, and cost effective. Then I will agree to do it, and once I agree to it, the discussion is over.As you may have guessed, that often means I end up taking a design into the office and saying "Is this OK?" They usually say "yes", stamp it, and give it back to me. Sometimes they resize a few things, that's about it.I've never worked with this particular engineer before so I don't get to pull that stuff on this job. So tomorrow I guess I'll see about a different engineer. It's up to the GC this time.But your point is very well taken. Nobody should ever take it upon themselves to deviate from stamped drawings for any reason. That is an invitation to tragedy.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Now I get it. I wasn't sure if you were doing this to put in a basement next door or extend the Wal-Mart parking lot next door.
In regards to the building you are working beside, why do you think the building will be damaged if you use some of the methods Bob suggested? Is this a 2 story, 10 story, 30 story?? New,old?? How deep is the foundation of this building? What is it made of? Where is the water table? etc. etc.....
How close to the existing building do you propose to put the new basement?
If you are going to case the hole all the way to the top, which I assume you have to do anyway, why don't you do as Dan suggested?
You certainly wouldn't have to use casings anywhere near 24" to do that and you would eliminate the I beams.
I don't understand how you could do it the way you first described without the top 10' above the concrete caving in?? Am I missing something??
Sounds to me like you are on top of the situation (more so than your design team)
<<If you are going to case the hole all the way to the top, which I assume you have to do anyway, why don't you do as Dan suggested?>>As far as I'm concerned, that's exactly what we're going to do. See Dan's post #9. I am quite sure that I owe Dan some beers, a bottle of 12-year old bourbon, or something. <G>I refined and summarized Dan's idea in a fax to the engineer today, I got back an unstamped sketch of his understanding of my fax which we (that is my crew and I) will most definitely not be executing. I know when to say no, and this is one of those times.I also think it's time for a new engineer.As I see it, we should be able to make this work with 5" x 0.188" grout-filled casing somewhere around 4' o.c. with 8x8.5 channel horizontal. This will be a real lot less expensive than the original design. There is a 5' return at midspan so there is a built in buttress there, and I can run each end wild past the building envelope and crib the ends so the longest face is 15' and every face is supported at both ends by something other than the vertical members.If I can get the GC's blessing I'm going to run this by a different engineer tomorrow. While I'm pretty comfortable with making judgements on the basis of experience, I am also definitely not qualified to specify any of these components or their assembly, and would always defer to someone who can do that legally. If I think that they know what they are talking about, that is. <G>I am also now going to insist on seeing the soils report. If it gets as tight as I think it does about 12' down, then we've got it made. If not, I'll rethink this.<<Sounds to me like you are on top of the situation (more so than your design team)>>Thank you for the vote of confidence. While I do appreciate that, I'd feel a whole lot better if I thought I was the least qualified party on this job rather than the most. <G>A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
I have seen similar things done often. But with several important differences. Most often, the steel would be dropped all the way to the bottom of the hole, and then the hole would be filled with "lean mix", a designed mix with no aggragate. If there are any elevation errors, a chipping hammer will quickly remove the mortar like material. Regardless, I would be inclined to say that you need an engineer and a shoring contractor involved.
<<I have seen similar things done often. But with several important differences. Most often, the steel would be dropped all the way to the bottom of the hole, and then the hole would be filled with "lean mix", a designed mix with no aggragate.>>That's what the original design was except the engineer specified concrete rather than CLSM. Steel to the bottom of the hole (about 18' deep), concrete fills the bottom 10' of the hole. <<If there are any elevation errors, a chipping hammer will quickly remove the mortar like material.>>As I said earlier, this is Type C poorly graded, no cohesion. We need to avoid taking a hammer into the hole, and we need to avoid all unneccessary expenses like laborers with chippiong hammers. <<Regardless, I would be inclined to say that you need an engineer and a shoring contractor involved.>>We have an engineer (I just didn't like his design). I am an excavation contractor with experience in demolition, commercial and residential construction, and heavy rescue. I've installed and worked under all kinds of shoring and retention. I have no trouble following an engineering sketch.The only unusal aspect of this job is that we can't drive anything at all for any reason, it all needs to be drilled in, and we have a budget that I need to meet.Did I post something here that gives the impression that I am an unemployed trim carpenter with a shovel?A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
"Did I post something here that gives the impression that I am an unemployed trim carpenter with a shovel?"Priceless! (and that's from a trim carpenter who's dug a few holes...)
Thanks. <G>If you are a trim carpenter who has dug a few holes then you are more talented than me. I can make a track excavator run the way it's supposed to, but it would be positively painful for you guys to watch me with a piece of crown molding. <G>Success is not the key to happiness. Happiness is the key to success.
-Albert Schweitzer, philosopher, physician, musician, Nobel laureate
(1875-1965)
Edited 2/6/2006 10:31 pm by Catskinner
Warning...Hijack.....it's my bosses who dig the holes....like my current one-demo out six pairs of fire doors & then find out the local AHJ won't allow it....& by the way, here's the summons...
I just try & dig my out .....
AHJ?Success is not the key to happiness. Happiness is the key to success.
-Albert Schweitzer, philosopher, physician, musician, Nobel laureate
(1875-1965)
Mr. Catskinner,
Sorry to but in. I just sit on the sidelines and read all of the very informative posts.
Anywho...
AHJ = (A)uthority (H)aving (J)urisdiction. The folks who write the building codes for the City, County, etc..
Thanks and good luck!
Thanks.I had some theories about what the "A" and the "H" might have stood for, but I couldn't figure out the "J".I guess I was wrong on all counts. <G>Success is not the key to happiness. Happiness is the key to success.
-Albert Schweitzer, philosopher, physician, musician, Nobel laureate
(1875-1965)
Actually, you were remarkably close for some of them.
If ignorance is bliss why aren't more people
happy?
the AHJ doesn't usually write the codes, just enforces them - aka the guy who "signs", making him (her) the person legally responsible for the final condition of the project - if the AHJ allowed the fire doors to be removed, then the AHJ could be liable for the fire coming through the "pretty" (but non rated) door - sorry about getting off topic
can you drive steelpiles?
Vancouver is doing this right now with their new convention center
can you drive steelpilesIt what we call sheetpile. 2+3=7
Catskinner,
"Any idea how to reliably check the level of the concrete as it is being placed?"
Gorilla glue 3/4" PVC to the top of an empty 2 liter soda bottle. Tape an audible laser detector at the proper elevation on the PVC rod after you set up the laser head.
You can pressurize the bottle (best practice) with a small piece of dry ice. If you fill the bottle with foam you could mechanically attach the rod so it flat out cannot seperate.
If you drop a vibrator down so that you can tell when you're getting close, and to keep the top of the mud level, you can drop the rod down at the end of the fill, instead of having to drop the entire load of mud on the "float."
SamT
Sam, that is a great trick. You've had to do this before? <G>Thanks!A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Cat,
I deal with drilled caisson all of the time. I would get the soil report and call your driller. These guys can put you on the right track right away. If you case these holes I think the cost would be out the roof. Most drillers can mudup the hole with super mud and keep the walls from collapse. Some times they will mud and case a hole but raise the case slowly as they pour and keep the case for the next hole. Do not pour concrete directly into the hole from 19'. That is a no no!! I forget what happens but the 19' drop will screw up the concrete.As far as stopping the concrete at the 10' level I have seen a heavy washer or what ever attached to the end of a cloth tape. Even with the hole full of super mud you can dangle the tape and tell pretty close (probably with in a inch or so) the level of concrete.
Since you have a signed engineers drawing, check and see if he specked PSI on the crete. If so fill some test cylinders and have break tested to cover your a$$ Hope this has been some help!
Vince,One of the things I love about this place is the amazing range of knowledgeable, skilled, and experienced folks all hanging around just waiting to help.That's good and useful words you posted here and I thank you.The concern of dropping concrete that far is aggregate segregation. You are of course correct, that's a problem.As SamT (I think) suggested, we'll probably be lightly vibrating it or rodding it into place. I may also run my own thoughts on a mix design past the engineer. I don't think that he is giving much thought to that.I spoke with my drilling guy yesterday afternoon. Once he understood the situation he was pretty enthusiastic. I think he's seeing it as an interesting little job and a chance to try some ideas. We are going to use his experience and knowledge to come up with a mud that he likes. As noted earlier, I think we are goint to abandon the original engineering concept that was on my desk when I made that first post yesterday. When I posted that original question, I had just looked at the original (stamped) design and asked myself "How the !#$%^&* is this going to work?"I showed the drawings to my two best guys (at least 35 years combined experience in the dirt betwen them) and they both said, "How the !#$%^&* is that going to work?"So I called the GC and his Super and asked them, "How the !#$%^&* is this going to work?"Turns out they were wondering the same thing and hoping I had an answer.So I came to you guys. Most of you had to be wondering, "How the !#$%^&* is that going to work?"OK, now that I have managed to crack myself up <G> . . . I think DanH gets most of the Milkbones (and bourbon if he likes) on this one, but I sure do appreciate almost every post here.If the GC will go along with this, we're abandoning the 2' drilled holes idea and the engineer who started all this silliness. Then I'll go to a new engineer with the design I like. I'm going to ask him to review it, correct it, note anything I missed, and stamp it. It has taken me more time to get a design I like than it is going to take to do the job.But, with the help of all of you, I think we've got that now.When I get drawings with a stamp on them I tend to take them seriously, in other words, analyze the concept on the terms that it is presented. Sometimes it just takes a little thinking out loud with others (like y'all) to realize that the design doesn't deserve any more thought and we need to take another run at it.So again, thanks. I sure do appreciate you and almost everyone else here taking the time to think this through with me.A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
> Do not pour concrete directly into the hole from 19'. That is a no no!! I forget what happens but the 19' drop will screw up the concrete.
IIRC, the rule of thumb is no more than 4' of free fall, lest the big rocks come unmixed from the goopy stuff and end up in separate layers.
-- J.S.
Yeah, but normally you'd pump this concrete in, and the pumper guy would have a hose to reach to the bottom. Does bring up an issue of the clearance for the hose, but I have to believe that this is a "normal" problem they have a ready solution for.
If ignorance is bliss why aren't more people
happy?
Nope.
Just put a bunch of other experiences together to fit your situation.
SamT