Construction of hollow thread bar combines drilling and grouting together.
Before construction, several processes should be prepared: connecting drill bit with hollow thread bar and shank adapter on drill machine; starting air-pressure equipment; preparing seriflux and grouting equipment.
During drilling process, hollow thread bar and drill bit should be located. Adjusting drill machine and drill boom to required hole site. Give seriflux and start hydraulic drilling rig. When encountering larger resistance, impact should be carried out.
Returning and hole flushing. Keep drilling and impacting until the first hollow thread bar finishes drilling. Then stop supplying seriflux.
Connection with the second hollow thread bar. When clamping jaw catches hollow thread bar, power head reverse rotates, which makes hollow thread bar get separation from shank adapter. Then power head rises more than 3m. Then put the second hollow thread bar at location between shank adapter and the first one. Starting drill machine and positive rotates until connecting tightly.
Keep drilling to meet required depth. Actual construction site often drills 30-35m.