This paper discusses the advantages of the foam DTH hammer , illustrates the structure and principle of the coring foam DTH hammer , and states its prospect applying to water-well drilling in the dry region.

The development of ZWC-95 mid-pressure air DTH hammer;

Inner Hole Obstruction Mechanism Analysis of DTH hammer;

Research and application on rock broken mechanism of pneumatic DTH hammer spherical tooth

Drilling experimental study of run-through DTH in complicated broken stratum;

Experimental Research on Run-through DTH Counter-Circulation Drilling Technique;

Visual Software Development on Pneumatic DTH Design;

The down-the-hole hammer drilling is to use compressed air as circulation medium substituted conventional mud,has solved problems of coalfield sealed fire area exploration high temperature water burst in boreholes,burnt rock loosen and developed fissures,instable and easy to collapse,broke through low drilling efficiency in hard rocks.

However, there are still many problems, such as: ambiguity classification of the complex stratums\' systematic; inexplicit of methods of determining reasonable drilling tools and regulations in complex stratums; uncertainty of the method of the depth of casing and its impact factors of Down-the-hole Hammer Drilling with Casing.