Question on the bolt length for tunnelling support

[lamy2781]

To calculate the bolt length for tunnelling support, I understand that the equation form Barton can be used. However, I found there two versions of the equation, which confuse me. I wonder any of you could know which is the correct one.

1) bolt length = (2+0.15B)/ESR
2) bolt length = 2 + (0.15B/ESR)

thanks

 

[msucog]

I believe it's the 2nd one but I suggest that you confirm that. Googling might find a reliable source.

Ryan Coggins, P.E., S.I.

http://www.linkedin.com/in/ryancoggins

 

[msucog]

Here is the first one I clicked on when I Googled. It's the best I can do with a minimal search and no reference books near me.

http://www.srmeg.org.sg/docs/Rock engineering - NUS Lecture Sept 06 (Handout).pdf

Ryan Coggins, P.E., S.I.

http://www.linkedin.com/in/ryancoggins

 

[lamy2781]

thanks msucog's reply!!

Why I have this question is because I found that when searching in the internet, I can find both:
e.g.

http://dk.nanoq.gl/Service/Hoerings...~/media/7DAFB26DAF514599AA993E244729B9CF.ashx

and

http://mining.itb.ac.id/file/bahan_kuliah/TA4111_Klasifikasi massa batuan.pdf

are using the first one.

This really made me confuse as both information could be find in the internet that generally being adopted.

 

[bridgebuster]

You can ask the FHWA. They have a web page devoted to tunnelling questions.

To ask a question:

http://www.fhwa.dot.gov/bridge/tunnel/qa.htm

FHWA Tunnel website:

http://www.fhwa.dot.gov/bridge/tunnel/index.htm