Study On The Drivage Efficiency And Drilled-hole Quality For The Hammer Of Percussion Drill

In this paper, the proposed rate of the percussion drills holes and stability ofdrilled holes is investigated based on all kinds of impact rig in practical engineeringapplications。At present, the percussion drill with its purchase of low cost, easyoperation of bored piling works have been widely used. In order to meet the need ofpractical engineering, percussion drills to the continuous improvement, the liftingcapacity has been greatly improved and equipped with a massive hammer. As the maintool, the hammer broken the bottom rock and soil of the hole; massive hammer in acertain extent can improve drilling rate, but also damage to the hole wall stability.The size and mode of action of the hammer on the impact of rock and soil in thebottom of the hole directly impact the scope of the destruction of the rock mass. Thereasonable structure and the quality of the hammer should be able to crush the rock andsoil within the scope of the hole, to avoid disturbance of the rock mass outside theaperture, get higher penetration rate and improve the quality of pile.Based on the hollow impact drill of widely used ZZ-6A impact drill, the bottomrock and soil of the hole impact effect are analyzed, the hollow impact drill structureand rock soil process were studied. On the basis of the previous calculation research onrockfall impact, proposed the impact of the hammer on the rock and soil in the bottomof the hole formula; Based on the fundamental solution of Mindlin problem usingmathematical software Mathematica to establish a ring loads on the rock and soil in thebottom of the hole plastic zone model；According to the formation of physicalmechanics parameters and pile hole diameter determined the reasonable range of theplastic zone, and further determines the annular load size and its distribution, thencalculate the quality of hammer and the radiu of horn head impact blade. Through theabove analysis provide the basis for a reasonable allocation of the quality and structureof the hollow impact drill.