If you are asking about water from surface runoff, one option would be to utilize drainage board and weep holes in your wall.
If you are asking about the water table, you need to either design for the hydrostatic pressure or find some means of permanently lowering and maintaining the water table.
I agree that it doesn't matter if a tieback is sucessfully tested. If you had a micropile job it might be a different story, since you don't typically test all of your production micropiles.
The answer to the question is easy for soil, as long as the grout is harder than the soil you should be...
There are several publications that list average bond stresses between grout and rock for differing types of rock, but none of the information I have at my disposal(FWHA & PTI) correlates grout compressive strength of grout to bond stress.
Intuitively, it seems like there must be a minimum...
There is essentially no reduction in compression. There is a reduction in tension.
If you are looking for full tension you might consider all thread bar as a component of your micropile.
If you need to get the casing to 100% in tension and you want avoid a lot of welding and reinforcing of...
The bending capacity doesn't usually control in micropile design. In the micropile industry, we often assume that flush threaded casing has 50% of the theoretical capacity in bending at the threaded joint. I was asked to "prove it" on a project, so I started this thread looking for help.
We...
I have just recieved the paper suggested by Erdbau. It is exactly what I was looking for.
I would recommend to others that are attempting to predict the bending capacity of flush threaded casing.
Thanks for the suggestion Erdbau!
If there is something in FHWA-SA-97-070, it eludes me.
I'm trying to quantify the capacity in bending, I'm not worried about compression.
Today the mailman delivered the paper that born2drill suggested. They tested 7"x0.5" casing in bending. It failed by thread jump. This particular casing...
The casing is the primary reinforcing for the micropile (no center bar).
The micropiles will be loaded in compression. The only bending would be a result of accidental eccentricity. I am told that the "building official" will not allow an exception to the above mentioned code requirement...
I agree that nothing beats an actual test.
One would think that others have tested the bending capcity of threaded casing and it might be possible to interpolate the data to the various casing sizes, so long as the material properties are known.
We are being asked to design micropiles to IBC 2006 code.
IBC 2006 Sect. 1808.2.7 requires that pile splices develop 50% of the pile capacity in bending.
We'd like to drill the low headroom micropiles utilizing male to female threaded casing. Does anyone know of a resource or method of...
I've read through this tread and the older thread. There are some good points and some good references. I'm not sure that its enough ammunition to convince some of the more stubborn engineers that we've all come across.
Has anyone ever come across a study that either supports or refutes the...
I'd install tiebacks through the basement wall. I've had success with this in underground parking garages. You'd use a limted access rig that can operate in low overhead conditions. The trick would be getting the rig into the basement.
If your rock slope is stable and you are just protecting against erosion, you might consider applying a few inches of fiber reinforced shotcrete to the slope.
