settlement calculations horizontal drilling

[johnl1234]

Can anyone point me in the right direction to obtain settlement calculations for horizontal drilling and tunnelling works ?

 

[Focht3]

Give us a lot more detail...



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[BigH]

Do you mean settlement or do you mean horizontal shaft drift (putatively "down&quot due to perceptions of gravity influence. Add this to the other info Focht3 wants.

 

[johnl1234]

OK Job is horizontally drilled hole 150 mm diamter approx 5 m below railway tracks. Ground is sandy clay with ballast on the top

 

[Zambo]

sorry no advice on settlement calcs, doubt there will be a problem but sure BigH and Focht3 can give the info. From a construction point of view some railway authorities expect pipes to be cased under railway tracks in case of a burst pipe causing washout. If necessary you can drill the hole to a bigger diameter, say 200mm, and pull in the pipe and casing at the same time.

Zambo

 

[Focht3]

Pretty small - and pretty deep (relative to the pipe diameter.) Hard to get excited about it.

How did you plan to accomplish it? Sounds like a good job for microtunneling.

By the way, where's the groundwater?



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[Zambo]

Directional drilling as JohnL suggests is probably the best option. Drill the hole under bentonite and pull the pipe in pre-jointed. Not as directionally accurate as some forms of micro-tunneling but depending on the equipment and pipe material probably cheaper and quicker.

I guess his problem is that some railway engineer won't accept that the small diameter and depth means that settlement calcs aren't really necessary.

If this is a water or gas main from either PVC, HDPE or similar the suplier may have standard details showing depths required under roads/railways.

Zambo