基于重整化方法的冲击载荷下岩石振动分析

摘要

Currently rotary percussion drilling is the most used and efficient rock breaking technology in deep hard formations drilling and the effect is remarkable.Based on vibration theory and the consideration of the gravity of rocks,a mathematical model of rock vibration under impact loads was established.Renormalization method was used to get the solution and MATLAB software was used to analyze the influence of various parameters on the vibration of the rock. Finally,laboratory experiments were conducted to verify the analytical results.It is shown that the movement of rock under drill bit's impact is mutual interference vibration between two harmonic vibrations.The vibration amplitude of the rock as well as the vibration velocity becomes larger with the decrease of rock density,the decrease of rock stiffness and the increase of the impact force.There is an inherent frequency of the rock.Vibration of the rock becomes more intense with the decrease of the difference between the impact frequency and the inherent frequency.When the high impact frequency equals to the inherent frequency,the vibration amplitude and vibration velocity reach the largest,which is the resonance. For revealing the crushing mechanism of the rock under dynamic loads and guiding the design of impact tools,analysis of the response of the rock under impact loads is of great significance.%旋转冲击钻井是当前钻进深井硬地层应用较多且效果显著的一种高效破岩技术。基于振动学理论，在考虑岩石重力的情况下，建立钻头冲击载荷下岩石振动响应的数学模型，采用重整化方法对其求解，利用 MATLAB 软件分析各参数对钻头高频冲击下岩石振动的影响，并进行了室内实验对理论分析结果进行了验证。结果显示：冲击载荷下岩石的运动为两个简谐振动的互扰振动；岩石的密度越小，刚度越小，冲击力越大，岩石的振动幅度越大，振动速度也越快；岩石存在一个固有频率，冲击载荷冲击频率越接近这个固有频率，岩石的振动越剧烈。当钻头高频振动频率和岩石固有频率相等时，岩石振动幅度和振动速度最大，即达到了共振。冲击载荷下岩石响应的分析对于揭示动载作用下岩石的破碎机理，指导冲击工具的设计具有重要意义。