DTH (Down-The-Hole) Percussive Hammer Drilling
DTH (Down-The-Hole) Percussive Drilling can be supplied by LDD where rock strength is sufficiently strong that standard rotary drilling becomes sub-economic due to slow production rates.
DTH hammer units are used with standard reverse circulation drill strings deployed on standard pile top drilling units. Drilled cuttings are removed from the drill face by reverse circulation in the normal manner. With DTH systems, the percussive action of the drill bits acts on the rock face to break rock at far faster rates of advance than standard rotary drilling when in very hard rock types.