凸轮型冲击旋压钻头成孔机理研究

Study on pore forming mechanism of cam bitin percussive rotary extruding drilling

摘要:

挤密钻头是潜孔锤冲击挤密钻进技术的关键所在，其结构形式直接影响着钻进效率、成孔质量和应用效果。应用非线性有限元理论，对动载荷作用下土体的弹塑性和压缩性的变化规律进行了分析。研究发现，常规钻头在冲击挤密钻进过程中产生的桩效应是导致钻进效率降低的主要原因。为了克服桩效应的影响，利用ANSYS/LSDYNA软件对阶梯式钻头和凸轮旋压钻头的钻进过程进行数值模拟分析，并通过实钻试验进行验证。数值模拟分析和试验结果均表明：凸轮旋压钻头能够有效避免钻进过程中土体回弹问题，降低桩效应对钻进效率的影响。试验结果与模拟结果相吻合，表明数值模拟的结果相对可靠。

关键词:冲击挤密钻进;桩效应;阶梯钻头;凸轮旋压钻头;数值模拟

Abstract:

The compact drill bit is the key of the DTH hammer percussion compact drilling technology. Its structure directly affects drilling efficiency, pore forming quality and application effect. Nonlinear finite element theory was used to analyze the changing laws of elastoplasticity and compressibility of soil under dynamic load. The result showed that: the phenomenon of piling effect is produced by conventional drill bits in the process of percussive compaction drilling is the main reason for the decrease in drilling efficiency. In order to overcome the influence of the pile effect, ANSYS/LSDYNA was used to perform numerical simulation analysis on the drilling process of stepped drill bits and cam spinning drill bits, and verified by actual drilling experiment. Both the numerical simulation analysis and the experiment results showed that the cam bit can effectively avoid the rebound problem of the soil during the drilling process and reduce the influence of the pile effect on the drilling efficiency. The experimental results are in good agreement with the simulation results, indicating that the numerical simulation results are relatively reliable.

Key words:percussive compaction drilling; pile effect; step bit; cam bit; numerical simulation