pneumatic DTH hammer are piston, valve distribution, inner cylinder, outer
cylinder, screw rod, and upper and lower joints.
In addition to the large diameter multifunction double rotary drilling rig and
pneumatic DTH hammer, other equipment shown in Table 11.13 is also used.
Fifty-five tons crawler crane and hole-type vibration hammer are selected for casing
lifting machine.
11.6.3 Construction Process
The construction technology of large diameter pneumatic DTH hammer drill is
shown in Fig. 11.44. The site of each main construction technology is shown in
Fig. 11.45. The technological process includes setting-out of pile position, positioning of pile machine, drilling and slag discharging, including stopping after
drilling outer casing into bedrock surface, then drilling bedrock with inner spiral rod
and DTH hammer to design hole depth, final hole, hole clearing, hanging and
installing steel cage, downward pipe, grouting underwater concrete, piling, pulling
out steel casing, and shifting of pile machine.
Inner cylinder
Valve seat
Spring
Check
valve
Lower joint
Drilling
bit
Hafu
Seal ring
Circlip
Lower joint
Piston
Outer cylinder
Spiral tube
Snap ring
Upper joint
Fig. 11.43 Main components
of large diameter pneumatic
DTH hammer
262
11 Pneumatic Down-the-Hole Hammer
cylinder, screw rod, and upper and lower joints.
In addition to the large diameter multifunction double rotary drilling rig and
pneumatic DTH hammer, other equipment shown in Table 11.13 is also used.
Fifty-five tons crawler crane and hole-type vibration hammer are selected for casing
lifting machine.
11.6.3 Construction Process
The construction technology of large diameter pneumatic DTH hammer drill is
shown in Fig. 11.44. The site of each main construction technology is shown in
Fig. 11.45. The technological process includes setting-out of pile position, positioning of pile machine, drilling and slag discharging, including stopping after
drilling outer casing into bedrock surface, then drilling bedrock with inner spiral rod
and DTH hammer to design hole depth, final hole, hole clearing, hanging and
installing steel cage, downward pipe, grouting underwater concrete, piling, pulling
out steel casing, and shifting of pile machine.
Inner cylinder
Valve seat
Spring
Check
valve
Lower joint
Drilling
bit
Hafu
Seal ring
Circlip
Lower joint
Piston
Outer cylinder
Spiral tube
Snap ring
Upper joint
Fig. 11.43 Main components
of large diameter pneumatic
DTH hammer
262
11 Pneumatic Down-the-Hole Hammer