1. Preparation Before Entering the Tunnel
Check power source
Ensure diesel/electric power unit is ready and fuel/electric connection is stable.
Inspect the equipment
Hopper, rotor (if applicable), pump, accelerator dosing pump.
Hoses: delivery hose, air hose, accelerator hose.
Nozzle: clean, free of blockage.
Prepare materials
Wet mix concrete must meet tunnel shotcrete requirements (usually slump 10–14cm).
Accelerator ready and connected.
2. Positioning at the Tunnel Entrance
Place the machine near the tunnel entrance so:
Concrete truck can feed easily.
Hoses can reach the working face (typically 30–100 m depending on pump capacity).
Lay hoses straight and smooth into the tunnel to avoid sharp bends.
3. Start-up Steps
(A) Power & System Check
Start the main power / diesel engine.
Run hydraulic system and check pressure.
Ensure air compressor is connected and air pressure stable.
(B) Prime the Pump
Fill pump with lubrication slurry (cement slurry or special pump oil).
Pump the slurry until the hose is fully wet and friction reduced.
4. Begin Pumping Concrete
Start feeding concrete into the hopper.
Start the pumping unit at low speed.
The operator at the nozzle position should stay in contact with the machine operator through radio/hand signals.
5. Accelerator System
Turn on accelerator pump.
Adjust dosage according to design (typically 4–8% of cement weight).
Ensure accelerator mixes evenly at nozzle.
6. Start Spraying at the Working Face
When concrete reaches the nozzle, begin spraying.
Maintain proper spraying distance (1.0–1.5 m).
Spray from bottom to top, edges to center.
Keep the nozzle perpendicular to the surface to avoid rebound.
7. Working Safety Notes
Keep all people away from the hose whipping zone.
Ensure ventilation is adequate inside tunnel.
Do not stand behind curved hoses.
Check rebound and adjust angle.
8. Shutdown After Finishing
Stop feeding concrete.
Pump water to clean hoses immediately.
Clean hopper, pump, and nozzle before concrete sets.
Shut down power.
