Difference between Jack and Boring and Microtunneling 2

[CivilG]

Could someone please tell me the difference between Jack and Boring and microtunneling. Also is one method better for beneath the water table than the other. Is one more precise for alignment and grade control? How to they dispose of the soil when the tunnel is being dug? Which is cheaper?

Any information would be helpful.

Civil G, P.E.

 

[Artisi]

Have you ever considered doing a literature research or at least have a look around Google to establish the differences in terminology.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[cvg]

microtunneling is done by a small TBM, usually a series of cutters at the face and a slurry pipe to remove the spoil. pipe is jacked in behind the machine. most jacking and boring operations are much more low tech. put a metal shield on the lead pipe and start pushing. use an auger or hand dig under the shield. remove the dirt using buggies or buckets.

 

[dicksewerrat]

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Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[greggy]

Jack-and-bore is used for horizontal pipe installations (beneath highways, rivers, etc.) where a push and a receiving pit are excavated. Contractor installs what looks like a small locomotive on rails with a rotating head to auger and push a casing pipe through the ground to the receiving pit. Then pipe is pushed through the casing.
In microtunneling, pits are not always needed and the contractor can steer the cutting head horizontally and vertically to the receiving location. Many times they overbore the hole and use bentonite drilling mud, then when they pull the head back through the hole they drag the new pipe with a cable. Plastic pipe is popular for this, but iron pipe can also be accomodated. If iron pipe is used, it should be polywrapped.
Microtunneling would be preferred over jack-and-bore in areas of high water table unless the push and receiving pits have pumps running to draw down the water level during the work to keep the pits safe for boring and assembling the pipe.

 

[rconner]

There are actually different variations or flavors of both. While not purporting to be an expert in the process, I think construction cost estimating particularly for such specialized pipeline methods is a complicated business, and results can vary widely with a whole lot of factors, probably not the least of which is the locale (including soil and groundwater conditions) and the availability of the specialty contractors(or subs), equipment and expertise to do the work in the area involved). As previously mentioned microtunneling (MT) involves newer technology/rather complex and some would argue more sophisticated equipment (I think early machines a quarter century ago went for about a million clams apiece, with mobilization for pushes a big part). Not surprisingly, if all else was equal and work was above the water table, I think the installed MT costs per foot etc. and particularly for short crossings were generally higher, and in some cases a whole lot higher for MT. I guess that may or may not be the case now, depending on lengths involved and conditions etc (I think far below the water table does favor MT).
[I've noticed the file at

http://your.kingcounty.gov/dnrp/library/wastewater/csi/tabula/docs/task1_memo01-08-09.pdf,

that while a little dated might give you a relative flavor of what may be involved.]

 

[bimr]

Kind of a broad topic. For the most part, these are not competitive technologies.

Jack and Bore:

http://www.portlandoregon.gov/bes/article/486791

Microtunneling:

http://www.portlandoregon.gov/bes/article/486793

Jack and Bore is typically limited to a maximum 3-feet diameter pipe. Jack and Bore is typically for road crossings with a maximum length of approximately 300 feet.

Microtunneling length is typically 500 to 1000 feet with a diameter of 10 to 136-Inch.

The project equipment is reviewed here:

http://rebar.ecn.purdue.edu/Trenchless/secondpage/AB.htm