牙轮钻工作参数与岩体强度对应关系的理论分析与实验研究
Theoretical and experimental studies on relationship between working parameters of cone drill and rock strengths
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摘要: 以露天矿开采为背景,基于牙轮钻单齿冲击压入破岩的机理,借助理论分析及现场实验,建立了牙轮钻的工作参数(进尺速度、钻杆轴压、转速)与岩体强度(黏聚力、内摩擦角)的对应关系。理论分析时,基于布西内斯科问题弹性力学解和Drucker-Prager塑性准则,给出了单齿压入破碎区域的几何形态,建立了单齿破岩体积与钻杆轴压、黏聚力、内摩擦角间的函数关系;并根据钻杆旋转一周单齿破岩体积的累积量和宏观破岩体积相等,建立了进尺速度、转速与单齿破岩体积的对应关系。理论分析的结果表明,单齿作用下,破碎区域基本呈椭球形,并在压入点附近的表层出现薄层破碎;进尺速度与转速呈线性关系,进尺速度与钻杆轴压呈3/2次方的关系,进尺速度与黏聚力呈-3/2次方的关系,内摩擦角对进尺速度的影响可以忽略。在鞍千矿南采区进行了牙轮钻钻进规律的现场实验,研究了进尺速度与钻杆轴压、转速、黏聚力间的对应关系,得到了与理论分析一致的结果。研究成果可以为牙轮钻工作参数的优化设计及岩体强度的动态测试提供依据。Abstract: The relationship between operating parameters of cone drill (drilling speed, drill pipe axial force, rotational speed) and rock mass strengths (cohesion, internal friction angle) is established by means of theoretical analysis and field tests based on the single-tooth impact and pressure rock fragmentation mechanisms. The geometrical morphology of broken area by single-tooth is obtained, and the relationship among single-tooth rock fragmentation volume, drill pipe axial force, cohesion and internal friction angle is established based on the Boussinesq elasticity solution and D-P plastic criterion in theoretical analysis. The relationship among single-tooth rock fragmentation volume, drilling speed and rotational speed established by the relationship that the accumulation of single-tooth rock-breaking volume and the macro rock volume is equal when the drill pipe rotates a circle. The results of theoretical analysis show that the fractured area basically exbibits ellipsoid and a thin layer in the surface layer under the single-tooth pressure. The relationship between drilling speed and rotational speed is linear, that between drilling speed and drill pipe axial force is 3/2 power, and that between drilling speed and cohesion is -3/2 power. The influence of internal friction angle on the penetration rate can be ignored. Field tests on the drilling law of conedrill are conducted in the south mining area of Anqian Mine, and the relationship among drilling speed, drill pipe axial force, rotational speed and cohesion is obtained. The theoretical analysis and the actual measurements coincide fairly well. The research achievements may provide a basis for the optimization design of working parameter of conedrill and dynamic tests on rock mass strengths.