S e c t i o n 1 - P a g e 7 May 2013 Condition of Thr eads - Thr eads should be inspected befor e installation. Incr eased friction on the thr eads adversely af fects the tor que tension r elationship. Fillet on Forged Head - For ged head r ock bolts should be inspected to ensur e a fllet of 1 / 8 " radius is pr esent wher e the shaft connects to the for ged head. Sharp transitions may weaken the bolt. Hole Length - Holes too short for the bolt in use may cause the shell to distort or inhibit pr oper tensioning of the bolt. Good practice suggests that the hole length should be equal to the bolt length plus shell length. Hole Condition - The hole should be cleaned and examined to ensur e the bolt will insert smoothly . Damage to the shell may r esult if it must be for ced into the hole. continued Installation Quality Guidelines Mechanical Rock Bolts The following ar e items to be awar e of when installing mechanical r ock bolts (for ged head and thr eaded both end [TBE] bolts): T ype of Gr ound - The natur e of the gr ound must be evaluated. Soft strata r equir es a lar ger plate washer and/or expansion shell bearing ar ea. Gr eater expansion of the expansion shell leaves may be r equir ed. Soft gr ound r esults in lar ger hole sizes for a given bit size (bit rattling and r eaming). Special anchors ar e available for soft gr ound. Excessively har d gr ound can be detrimental as well. Har d gr ound can r esult in poor anchorage as the shell is unable to “bite” into the r ock. Scaling - The gr ound should be thor oughly scaled i.e. barr ed down, befor e drilling and bolting. Periodic r e-scaling may be r equir ed while drilling. Str ength and Y ield Capacity of Bolt - The mechanical pr operties of the bolt should be appr opriate for the gr ound conditions, bolt length and bolting patter n. Pull tests and tor que-tension tests should be performed to determine yield str engths and anchorage capacities of the bolts being used. www .dsiundergr ound.com