I'm "hardening up" my control network, before winter sets in. Currently I've got 12" spikes (with a dimple turned in a lathe) at most stations. I want to pull them up and replace with two or three feet of 1/2" rebar with caps. Not more than two stations into the process, I hit something hard...very hard...not unusual around here. So the question is, if you don't know how big the thing is you're hitting a foot or more deep, would it be easier to excavate the spot, place the rebar and back fill, or just rent a battery powered hammer drill, and punch through whatever is there? I'm leaning towards the latter, if for no other reason that it would hold the position with tighter tolerances. Not to mention that if it IS big, digging's not going to help. Ideas welcome.
rfc, post: 396554, member: 8882 wrote: I'm "hardening up" my control network, before winter sets in. Currently I've got 12" spikes (with a dimple turned in a lathe) at most stations. I want to pull them up and replace with two or three feet of 1/2" rebar with caps. Not more than two stations into the process, I hit something hard...very hard...not unusual around here. So the question is, if you don't know how big the thing is you're hitting a foot or more deep, would it be easier to excavate the spot, place the rebar and back fill, or just rent a battery powered hammer drill, and punch through whatever is there? I'm leaning towards the latter, if for no other reason that it would hold the position with tighter tolerances. Not to mention that if it IS big, digging's not going to help. Ideas welcome.
Dig down to the bed rock, then pour concrete inside short section of 12" diameter sonotube. Place your rebar in concrete.
rfc, post: 396554, member: 8882 wrote: rent a battery powered hammer drill, and punch through whatever is there? I'm leaning towards the latter
I would lean that way too...
Question(s):
- Why do you want to replace the spikes?
- Do expect to replace them in the exact position?
- How do plan to achieve this?
RADAR, post: 396558, member: 413 wrote: I would lean that way too...
Question(s):
- Why do you want to replace the spikes?
- Do expect to replace them in the exact position?
- How do plan to achieve this?
1. Only that deeper would be better than shallower...given NE frost cycle. the current spikes seem reasonably stable, but I thought they'd be more stable if they were deeper. If frost heaving is only going to move them vertically, it probably wouldn't be an issue, but I'm not sure of this.
2. Yes, of course.
3. Initial plan was to pull the spike as vertically as possible (they're 3/8" diam); replace with rebar; drive to refusal or length of rebar, and cap.
Dewalt 18v or 20v SDS hammer drill
both will run on 20v battery, the 18v tools need an adapter
18v has 7/8in chuck
20v has 1in chuck
Assortment of rock and concrete bits that fit your monument size
1in auger
2 1/2in auger
In very hard ground I can dig 6 one inch holes a foot deep faster than I can dig 2in with a pick and shovel
You can feel or hear when you hit something just like with a probe
Here's what you need...
rfc, post: 396562, member: 8882 wrote: 3. Initial plan was to pull the spike as vertically as possible (they're 3/8" diam); replace with rebar; drive to refusal or length of rebar, and cap.
I might suggest setting reference points, before you pull the spikes. That way, you can check to see that point is good.
Spikes move real easy in winter. Cordless hammer drills are next to useless. I use a bosch sds max Drill with a honda 2k generator.
First you get a license to handle dynamite. Then.......................................................
Jon Collins, post: 396579, member: 11135 wrote: Spikes move real easy in winter. Cordless hammer drills are next to useless. I use a bosch sds max Drill with a honda 2k generator.
The other element would be to make a wooden or high-density plastic template that the SDS bit will just barely clear. I use pieces of 1 x 4 lumber with enough extra on the ends to step on to hold the template in place while drilling. Otherwise, you run the risk of the bit skipping off a rock surface that isn't perfectly horizontal and the hold wandering well off the target.
I would view this as an opportunity to buy a new hammer drill. You can say "I needed it!"
You ever run into Larry and his other brother Larry?
Kent McMillan, post: 396587, member: 3 wrote: The other element would be to make a wooden or high-density plastic template that the SDS bit will just barely clear. I use pieces of 1 x 4 lumber with enough extra on the ends to step on to hold the template in place while drilling. Otherwise, you run the risk of the bit skipping off a rock surface that isn't perfectly horizontal and the hold wandering well off the target.
That's a good idea. Sort of like a drill bushing. I know there's nothing hard down at least a foot, so the undisturbed dirt around the existing hole will provide some lateral guidance, but the 1 x 4 or 2 x 4 idea is a good one. Thanks. Looks like I need a hammer drill too (but probably not the one GeeOddMike suggests):scream:
RADAR, post: 396571, member: 413 wrote: I might suggest setting reference points, before you pull the spikes. That way, you can check to see that point is good.
I was going to do this too...two more spikes set 10' away at right angles to each other, taped to the spot before disturbance. Thanks.
Dave Karoly, post: 396592, member: 94 wrote: You ever run into Larry and his other brother Larry?
That would be "Hi, I'm Larry, this is my brother Darryl, and this is my other brother Darryl!"
Years ago, I had two puppies that looked exactly the same. I named them both Darrell.
James
[MEDIA=youtube]5yyB06HvAjI[/MEDIA].
rfc, post: 396554, member: 8882 wrote: I want to pull them up and replace with two or three feet of 1/2" rebar with caps.
BTW, I forgot to mention it, but I don't think that rebar will resist frost heave as well as a smooth bar would. It's entirely possible I'm wrong about that detail, but it seems to me that the top part of the ground would freeze first and that, grabbing the deformations on the bar, the upper frozen layer would tend to pull the bar out of the ground. The New Englanders would have a better idea about whether that is a mechanism to deal with or not.
I just have never seen stuff like that go back into the SAME hole. So, here are my thoughts...
Do you have ELEVATIONS on those?
Like others have said, you are sort of in trouble. How many of these do we need to go and reset?
My thoughts are to buy a CORN tripod. (Something you can work under, without disturbing.) Get some sort of GOOD powered hammer.
Job sequence would be:
Carefully set up the tripod, Tribrach, and LASER Plummet. To do a really good job, a small step ladder is in order. Measure and record the HI.
Pull out the old ctrl spike.
Get your trusty new machine, and hammer drill, or jackhammer it down. Use a hook on the tripod, to check your HI.
drive the new marker to refusal, or whatever you are trying to do.
If elev matters, use the Box tape, to get the elevation right. Use the Laser plummet to make a new dimple in the top of the new control point.
Or, you might just get a Javad. (wink) But, that's another story!
hope you get it.
Another idea is to install a COORS station at a suitable place. Might be less work.
Nate
RFC
You might be able to get the new points where the old ones were, but you may not get them there exactly, which introduces "slop" in your baseline. If your soil is like the stuff we have here, there are lots of hard rocks to hit and deflect a rod and shallow granite or gneiss for bedrock; not easy to drill.
You are doing this for a a learning exercise if I recall. It may be easier to set your new, more substantial points near the old ones, then tie them all together with some new measurements and see what Star Net does for you. I follow that scenario during the construction phase of a project. Over time much of the original baseline vanishes, but Star Net helps keep all the control in order.
Ken
Excellent thinking, Ken. New points with the old ones to compare data with.
Not going to happen in New England, frost everywhere, very deep some years (4'+) and very little other years. Even if the bottom of the rod is below the frost line the top will be encased in the frost layer and probably will move (up and down mostly). The only things that work are bolts in ledge or the NGS BMs with the bar inside a sleeve, for which you need a big rig drill and lots of $$. You might try one of the Berntsen bars that have an expanding anchor at the bottom, if they are driven below the frost line they may not move, or much anyway.
As far as the rock thing goes, try moving the point a few feet and try again (yes a new set of observations will be required). You can usually tell what you are hitting when you get near, or to, refusal - if the rod continues to move down very slowly it may be a root which, with effort, and a bigger hammer, you can usually get through - if it just gets real hard to pound and the rod doesn't move you are probably on a large rock. I have found that when you hit the giant rocks or ledge there is an abrupt stop to all movement and when you hit the rod you feel the really solid ledge and sometimes you will get a little bounce back or a ringing, but there is no question that you aren't going to go any deeper , get out the hacksaw. You may know all of this but I just thought that I would pass along what I have observed after driving gun barrels, pipes and re bars into New England soil for 50 years.
T.W.
