DTH pneumatic bottom-hole: 4 sizes for rock, concrete, and asphalt

When the pneumatic bottom-hole is needed

On rocky, limestone, reinforced concrete, or asphalt-covered soils, direct pile driving is not possible. The DTH pneumatic bottom-hole solves this by creating a hole through percussive demolition, after which standard driving can proceed normally.

The two most common situations are: in the road sector, guardrails must be installed on existing road surfaces where asphalt and sub-base prevent direct driving. In solar, rock at less than 1.5–2 m depth is the most common geotechnical problem: the DTH pre-drills through the hard layer so the foundation pile can continue.

Four sizes for every need

The TURCHI DTH range includes four bottom-hole hammers, each optimised for a specific diameter range and material:

• DTH 3" — Ø 90–105 mm. The most compact: pilot holes in rocky terrain, anchors, and small-diameter pre-drilling.
• DTH 4" — Ø 110–152 mm (6 bit sizes). Covers 80% of rock applications and is the best-seller in the range. Rock, granite, reinforced concrete, asphalt.
• DTH 5" — Ø 140–180 mm. For hard rock, granite, and basalt. Deep foundations and large-diameter holes.
• DTH 6" — Ø 152–220 mm. The most powerful: any rock formation, micropiles, and large-diameter foundations up to 220 mm.

All hammers use hydraulic rotation powered by the pile driver's hydraulic unit and require an external air compressor.

Mounting: lateral or central head

The DTH bottom-hole mounts on one of two rotary heads available for the TURCHI 260F and 300F:

• Lateral rotary head — 1 hydraulic motor, augers and DTH up to Ø 200 mm. Positioned off-centre from the hammer, it allows drilling offset from the machine axis — useful next to existing structures or in staggered layouts.
• Central rotary head — 2 independent hydraulic motors, up to Ø 500 mm. Mounted on-axis, it provides double torque for very hard soils and maximum stability.

The same rotary head can also mount hydraulic augers (Ø 80 to Ø 400 mm) for clay or gravel soils where direct drilling is more effective than percussive demolition.

Typical applications

• Road guardrails — pre-drilling through asphalt and sub-base for guardrail post installation on existing roads.
• Solar with shallow rock — drilling through rock layers at less than 2 m depth to allow foundation pile driving.
• Micropiles & foundations — holes up to Ø 220 mm for micropiles in any rock formation.
• Anchors & tie-backs — small-diameter pilot holes for anchors on existing structures.

To assess which DTH size suits your jobsite, contact the TURCHI technical team with the available geotechnical data.