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在钢粒或硬质合金钻探中,当钻孔发生超径时,往往是有先兆的,例如坍塌掉块、多见渣滓等。而小口径金刚石钻探则不然,当局部出现程度不同的超径时,往往难以提前察觉异常。况且钻具转速高时小口径的钻孔一旦出现超径,后果也较严重,所以防治工作特别重要。一、金刚石小口径钻孔超径的特征和危害金刚石小口径钻孔的超径,除了发生在断层、破碎带内,还常见于松软地层,如风化半风化层、煤层、岩盐等可溶性矿层,解理发育的灰岩、千
In steel or carbide drilling, when borehole over-diameter occurs, there is often a warning, such as collapsed blocks, more common dross and so on. However, small-diameter diamond drilling is not the case, when the local emergence of different degrees of super-diameter, it is often difficult to detect abnormalities in advance. Moreover, when the drill speed is high, small-caliber holes in the event of over-size, the consequences are more serious, so prevention and control work is particularly important. First, the small diameter diamond borehole characteristics and hazards of ultra-small diameter drill hole diameter, in addition to occurred in the fault, broken belt, but also common in soft formations, such as weathering semi-weathering layer, coal seam, rock salt and other soluble ore, Limestone cleavage development, thousands