Grouted tunnel studs versus rock bolts

March 21, 1980

Mr. D. R. Wanhatalo
Project Manager
Fruin-Colnon Corporation and Traylor
Bros. Inc. and Onyx Construction & Equipment Inc.
[Recipient address omitted]
Dear Mr. Wanhatalo:

This is in reference to our letter dated January 26, 1980, concerning your request for a permanent variance and interim order from Section 1926.800(h)(2)(iii) - Tunnels and Shafts - Testing, of the Safety and Health Regulations for Construction.

You state that you are required to use a threaded bolt that is fully encapsulated in epoxy. You further state that the testing procedures in the tunnel contract specifications state that you must use a "pull test" method to determine the strength of the bolt. You have requested a variance to use the "pull test" in lieu of using a torque wrench to determine if the bolt meets the necessary torque as required by Section 1926.800(h)(2)(iii).

The OSHA standard 29 CFR 1926.800(h)(2)(i) through (v) refers to tunnel area examination at the start of each shift and frequently thereafter. Section 1926.800(h)(2)(iii) requires that torque meters and torque wrenches shall be available at tunnels when rock bolts are used for ground support, that frequent tests shall be made to determine if bolts meet the required torque, and that the test frequently shall be determined by rock conditions and distance from vibration sources.

Rock bolts are bolts driven into a drilled hole, not grouted or cemented with resins. They perform specific functions by reaching deep into solid undisturbed rock and providing information concerning the motion of the rock formation behind the area being excavated. The frequent torquing of the rock bolts provides the necessary information concerning the rock condition, possible motion within the area to be monitored, and the actual holding capability of the individual rock bolt.

The grouted studs do not perform any of the rock bolt functions listed above. A grouted stud could fall under tension when blasting, through vibration, or any time after one of these. Grouted studs are not rock bolts. Functionally they are different from rock bolts due to their structural features.

Therefore, a variance from Section 1926.800(h)(2)(iii) for grouted studs is unnecessary. Grouted studs are not subject to the standard. However, in those locations where it is determined that a rock bolt is required, the necessary testing as required by Section 1926.800(h)(2)(iii) is mandatory.

Affected employees and their authorized employee representatives shall be notified of this clarification in the same manner they were informed of your application for a variance.

No further action will be taken on your request for a variance. If I can be of further assistance, please contact my office at (202) 523-7144.

Sincerely,
James J. Concannon Director
Office of Variance Determination