Down the hole hammers, or DTH uses a jackhammer to shatter hard rock into small cuttings and dust. This is extracted by air, water or drilling mud. It is one of the quickest ways to penetrate rock such as basalt, grit, or welded tuff.

Pneumatics transmit intensive impact energy with low energy loss for excellent rock breakage, high penetration rates and high productivity. The jackhammer(s) produce a straight, accurately placed clean bore hole. DTH is significantly quicker than drilling techniques in these hard rock situations.

CLL’s DTH hammers produce a quality hole from 450mm to 1000mm in diameter, down to a depth of 26m.

Our Casing Driver System (CDS) allows CLL to simultaneously install a casing to a desired depth, while hammering the pile. This progressive casing controls the collapse of loose materials as the hole is being produced.

DTH hammers transmit intensive impact energy with low energy loss. This results in good rock breakage, high penetration rates and high productivity. The equipment is designed to give optimal hole quality, reliability, and long service life, as well as the best blasting results and low total operation cost. In few words…when it comes down to drilling into rock this technique is the fastest by far!

DTH technique is an alternative to conventional rock coring when thick layers of materials in the 20Mpa plus are encountered, these layers are generally formed by basalt deposits, grit, or welded tuff. When possible, the DTH method is significantly quicker than coring techniques. We can typically achieve approximately 20-30lm/day using our DTH rig compared with only 1-2m/day achievable if the piles were to be cored.

“DTH hammers are a way to deal with hard rock up to 250 MPa. It’s the go-to method for situations where there’s basalt, granite and many limestones where conventional boring would be slow and inefficient. Often we find that conditions below-ground have layers of basalt, grit or welded tuff fused volcanic ash and volcanic debris.”

“Down the hole hammers are just one of the specialised rigs we have at CLL. Our expertise and equipment makes us the right people for all jobs. In a nutshell, we know what we’re doing, and can cost-effectively deal with whatever situation mother nature throws at us.”

—Terry Donnelly