Difference between Jack and Boring and Microtunneling
Difference between Jack and Boring and Microtunneling
(OP)
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.
Any information would be helpful.
Civil G, P.E.





RE: Difference between Jack and Boring and Microtunneling
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.)
RE: Difference between Jack and Boring and Microtunneling
RE: Difference between Jack and Boring and Microtunneling
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Difference between Jack and Boring and Microtunneling
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.
RE: Difference between Jack and Boring and Microtunneling
[I've noticed the file at http://your.kingcounty.gov/dnrp/library/wastewater..., that while a little dated might give you a relative flavor of what may be involved.]
RE: Difference between Jack and Boring and Microtunneling
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/...