基于花岗岩地层全液压钻机成孔特点的清孔工艺改进OA

In response to the technical challenge of blurred images caused by wall-attachments in granite areas,this paper systematically analyzed the limitations of conventional hole-cleaning process with clear water circulation after wireline core drilling with full hydraulic drill,based on an underground engineering survey project.The study shows that although this process can remove suspended rock debris,it is notably inadequate in removing dense adhering layer formed by drilling tool rust and mud cake oxidation above water level.To overcome this,a combined hole-cleaning process"high-pressure preliminary flushing+targeted mechanical brushing"is proposed,supplemented by preventive measures such as drilling fluid maintenance and lifting optimization.Comparative tests were conducted for a 420 m borehole(water level 180 m).Test results indicate that the proportion of borehole sections with clear images increased from 68.5%to 88.7%for entire borehole,and from 55.0%to 86.0%for above-water section,representing an increase of 31%and showing marked improvement.It is concluded that the combined process can precisely remove the oxidized adhering layer,making the imaging quality of above-water and below-water sections more consistent,and effectively ensuring the accuracy of fracture identification and geological interpretation.Under special working conditions(fault fracture zones and inclined boreholes),the principle of"wall protection priority,low pressure and large displacement"should be followed.These research results can provide practical reference for refined geological investigation in granite areas.