1. Preparation before drilling
Survey and mark bolt positions
Use the tunnel support drawing to mark lateral bolt spacing, angle, and elevation on the sidewall.
Check the rock drilling jumbo
Ensure the boom rotation, swing, and tilt functions work smoothly.
Confirm the feed beam length matches the designed bolt length.
Check drill rods, bit diameter, water/air flushing system.
Safety setup
Scale loose rock on sidewalls if necessary.
Keep personnel away from the drilling radius.
2. Positioning the jumbo
Drive the jumbo close to the tunnel sidewall, keeping:
Stable chassis position
Enough boom working space
Use hydraulic outriggers (if equipped) to stabilize the machine.
3. Boom adjustment for lateral drilling
Rotate the boom horizontally toward the sidewall.
Adjust:
Boom swing → align with bolt location
Feed beam tilt → match bolt inclination (usually 5°–15° upward or as designed)
Feed beam rotation → keep the drill perpendicular to the rock surface
👉 For single-arm jumbos, lateral bolts are typically installed by:
Rotating the boom sideways
Using feed beam articulation to reach upper and lower sidewall positions
4. Drilling the bolt hole
Start drilling at low percussion and feed pressure to prevent bit wandering.
Drill to the designed depth (bolt length + grout allowance).
Use water or air flushing to remove cuttings and ensure clean holes.
After drilling:
Retract the drill rod slowly
Re-flush the hole if needed
5. Installing the anchor bolt
Depending on bolt type:
(1) Resin anchor bolt
Insert resin cartridge into the hole
Push the bolt in with slow rotation
Hold until resin sets
(2) Cement-grouted bolt
Insert bolt into the hole
Use grout pump to inject cement grout from the bottom up
Ensure full grouting (grout return visible at the collar)
(3) Expansion bolt
Insert bolt
Tighten nut to specified torque to expand the anchor
6. Plate and nut installation
Install bearing plate and nut
Tighten to the specified torque
Check bolt alignment and seating
7. Quality control and inspection
Verify:
Bolt length and angle
Grouting fullness
Tightening torque
Record bolt installation data as required
Typical parameters (reference)
Bolt length: 2.0–4.0 m (project-dependent)
Hole diameter: 32–45 mm
Bolt angle: Horizontal or slightly upward
Spacing: As per support design
Key advantages of using a rock drilling jumbo
Accurate bolt angle control
High efficiency for sidewall support
Reduced manual labor and improved safety
