Yosemite Rock Bolting Spec

8/21/2019 Yosemite Rock Bolting Spec

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Section 260. ROCK BOLTS

Delete the entire section and add the following:

260.01 Description

This work consists of furnishing and installing either tensioned or untensioned fully grouted rock

bolts. Tensioned rock bolts are preferred to maximize rock mass stabilization by mobilizingrock-on-rock friction; however untensioned dowels may be used if the !ontractor can

demonstrate suitable long-term performance. "t is the intension of the pro#ect to install spot bolts

as recommended by the !ontractor and approved by the !$ avoiding pattern bolting foraesthetics reasons. To further enhance pro#ect aesthetics every effort should be made to limit

bolting immediate to the roadway. %earing plates bolt heads and protruding bar must be

removed from the final bolt installation incorporating a countersunk finish with a cuttings-based

grout patch to avoid bolt detection from passing motorists. &ock staining shall also be used on

the freshly blasted rock slope per 'ection ()* further aiding in hiding bolt installations.

260.02 Material

!onform to the following 'ections and 'ubsections:

+rout ,. /e0

&ock %olts ,.*

Construction Requirements

260.0 Su!mittal. 1t least , days before the installation of rock bolts submit the followinginformation:

"a# 2vidence that the foreman has a minimum of 3( hours and the drill operator has aminimum of 3 hours of satisfactory work in similar installation of tensioned and

untensioned rock bolts.

"!# 1ll supporting engineering calculations for recommended bolt type size spacingdepth/s0 of placement angle/s0 of placement anchor bond length re4uirements etc. as

prepared by a licensed engineer for the typical ground conditions anticipated at the site.

'pot bolting of specific rock blocks ranging in size from 3-3 cubic meters should be

assumed for the design. The environment should be assumed to be non-corrosive and freefrom stray currents. 1ll design assumptions factors of safety installation re4uirements

should be clearly described for evaluation by the !$.

"c# 5roposed rock bolt couplers bearing plate anchor unit flat washer and beveled washerspecifications including manufacture6s data sheets.

"$# !omplete specifications and manufacturer6s data sheets /as applicable0 and proper

placement procedures for polyester resin and7or cement grouts.


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"e# Drilling methods and type of e4uipment including procedures for tensioning bolts and

providing a countersunk finish as described in ).3.

"%# +eneral construction se4uence prior to and following re4uired blasting and scalingoperations. Describe safety re4uirements of all drilling and bolt installation operations

including hazard protection related to falling rock and7or bolting materials and e4uipment.

" !omplete procedural description of the installation of the selected bolt fixture. Describethe manner in which corrosion protection is ensured how bolt installation and grouting will

be conducted across open #oints etc. to achieve a fully grouted well-protected installation.

"'# Description of test procedures to be employed to ensure bolt anchorage capacity is beingachieved and applied tension levels are appropriate per the submitted design.

"i# !alibration data for e4uipment used to verify design loads. 'ubmit results of calibration

tests performed by an independent testing laboratory within the last ) days.

1llow ( working days for acceptance or re#ection. Do not begin work until submittals have been

approved.

The !$ may re4uire modifications of any bolting plans or procedures during the duration of thepro#ect. $btain approval from the !$ for any modifications to the submitted bolting plans.

260.0( Roc) Bolt.'ize the bolt so the design load does not exceed ) percent of the minimum

guaranteed ultimate tensile strength of the bolt. 'elect and fabricate bolts to carry the specified

loads. 8tilize epoxy coated or galvanized bolts to maximize corrosion resistance.

260.0* +an$lin& an$ Stora&e. 5rotect bolts from dirt mud water and other harmful

substances to avoid damage and corrosion. Do not use rock bolts that are heavily corroded

pitted damaged due to welding or show signs of abrasions cuts or nicks.

260.06 ,nstallation. Drill holes at locations and depths as recommended by the !ontractor6s

engineer and approved by the !$. Drill holes to the diameter specified by the bolt and7or resincartridge /if used0 manufacturer and to a depth of * millimeters beyond the end of the

specified rock bolt or as specified by the manufacturer. !lean holes of all drill cuttings sludge

and debris before the rock bolt is inserted or grout is in#ected into the hole. Drill holes normal tothe rock surface unless otherwise specified by the plans or the !$.

%e aware that special drilling and grouting procedures may be re4uired within the rock mass to

accommodate #oint and fracture apertures in excess of (mm.

!ouple sections together when standard commercially available lengths are exceeded and

according to manufacturer6s recommendations. 5rovide a center stop for connecting sections sothat an e4ual length of thread connects each section. 5rovide couplings that e4ual the

manufacturers guaranteed ultimate strength for the rock bolt. Do not fabricate couplings in a

manner that interferes with the flow of grout.

9or cement grout anchored bolts apply tension to the anchor bond section of the bolt installation

after the time specified in Table )-3. 1fter tensioning fully gout the remainder of the bolt to

the prescribed finish at the collar of the hole. &emove nuts and bearing plates following full


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column grouting after the time specified in Table )-3.

Ta!le 260-1

rout Curin& Time

Cement T/pe"Da/s#

" (

"" (

""" *

9or bolts anchored with polyester resin use fast setting polyester resin cartridges in the distal

anchorage zone and slow setting polyester resin cartridges in the pre-tensioned zone with geltimes consistent with rapid installation /per manufacturer6s recommendations0. 'elect cartridge

diameters in accordance with the manufacturer6s recommendations to ensure complete

encapsulation of the rock bolt and satisfactory in-hole mixing. %reak and mix resin cartridges by

spinning the bolt as it is inserted into the drill hole according to the manufacturer6s instructions.&emove nuts and bearing plates after the slow-set resin has achieved full set.

1ll bolt installations shall be completed with a grout patched countersunk finish re4uiring nuts

washers bearing plates and protruding bar to be removed following full grout7resin set.

"nstallation methods that allow the bar tensioning assembly to be detached behind the bearingplate and within the hole avoiding the need to hammer out a countersink in the bedrock are

preferred. +rout patches should incorporate drilling cuttings within the mix to best match the

color and texture of the rock mass. The !$ shall approve the countersinking method and grout

mix.

260.0 Tensionin&. $nce the anchorage zone has achieved the re4uired bond strength applytension to the bolt with a calibrated tor4ue wrench to 3( percent of the design load. 1s a prooftest demonstrate that this initial load can be maintained for a minimum of 3 minutes. 8pon

proof testing completion lock all bolt installations off at the specified design load.

Tension polyester resin anchored bolts immediately after the fast-set resin in the distal anchorage

zone has set up and before the slow-set resin in the pre-tensioned zone has set up. Tension

cement grouted bolts after the anchorage length has been grouted and the grout has set up the

recommended time but before the pre-tensioned length is grouted. Tension mechanicallyanchored rock bolts immediately after insertion into the drill hole according to the

manufacturer6s recommendations and the approved bolting plan. 9ill the hole of mechanically

anchored bolt installations with cement grout immediately following anchor set and bolttensioning.

1llow the bolt to remain in place if:

"a# The bolt can be tensioned to 3( of the design load and the load can be held for 3

minutes.

"!# The design load is maintained after final grouting has been accomplished.


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&eplace any bolt that does not meet /a0 or /b0 in a manner and in a location approved by the !$.

260.0 cceptance. aterial for rock bolts will be evaluated under 'ubsections 3). and

3).*.

"nstallation of rock bolts will be evaluated under 'ubsections 3). and 3).

Documents

Yosemite Rock Bolting Spec