Realization of automatic percussive drilling by microcomputer control system;

GCF-20A reverse circulation percussive rotary drill rig is a multi function drill rig with percussive drilling as the main means and rotary drilling as supplemented.

cone bit/disc cutter drilling method, percussive drilling method (no circulation and reverse circulation) and air/fluid powered DTH drilling method, is described with concrete proposals initiated for increasing the technical level of large diameter rock socket drilling.

Problems of impact rammer in percussion drilling of pebble bed;

The description is made of the introduction and analysis of the popular drilling hole technique that used in large boulder formation, including normal drilling technique such as digging, percussion drilling, rotary drilling, large diameter DTH drilling, explosion drilling technique and combined drilling technique.

In which,rotary drilling is suitable to strata with pebbles grain-size<80-100mm, percussion drilling requires total amount of pebbles<200mm not exceed 50%,and strata uniform,while the percussion rotation drilling is suitable to strata contain boulders.

The paper introduced the characteristics of DTH drilling with simultaneous casing technology,SP series of simultaneous casing drilling tool and the application of DTH drilling with simultaneous casing technology in drilling in complicated formation,such as control of geological hazard,hydropower construction,foundation treatment for urban high-rise building,highway and rai.