旋压钻进破岩的应力特征研究

Study on the Stress Characteristics of Rock Breaking by Rotary Drilling

准确获取岩石钻进细观参数是评价研磨和可钻性的有效方法。针对圆柱平底刚性钻头,利用ABAQUS软件建立钻头旋压岩石的相互作用模型。基于Drucker-Prager本构模型以及岩石的试验力学参数,分析了岩石表面单元发生破坏时钻头对岩石径向应力和轴向应力分布规律,对钻头与岩石接触的中心位置和边缘位置的应力变化进行分析。结果表明:岩石与圆柱形钻头接触部分的边缘点失效早于中心点,中心点破坏时的峰值应力大于边缘点,钻头进尺位移达到0.0603 mm时岩石中心点发生破坏,岩石在旋压作用下的应力是静态压入时的5倍,岩石轴向应力有效传递范围为16 mm,径向应力呈对称性分布,中心点处应力最小为17.74~23.55 MPa,0.533倍的应力半径达到峰值为51.31 MPa,约为砂岩抗压强度的三分之二。研究成果为圆柱平底刚性钻头旋压钻进岩石的耐磨性和可钻性评价提供理论基础。

Accurately obtaining the microscopic parameters of rock drilling is an effective method to evaluate grinding and drillability.Aiming at the cylindrical flat bottom rigid bit,the interaction model of rock spinning by bit is established by ABAQU.Based on Drucker-Prager constitutive model and experimental mechanical parameters of rock,the radial stress and axial stress distribution of rock caused by drill bit when the rock surface element is damaged are analyzed,and the stress changes at the center and edge positions of the contact between drill bit and rock are analyzed.The results show that the failure of the edge point of the contact part between the rock and the cylindrical drill is earlier than that of the center point,and the peak stress of the center point is greater than that of the edge point.When the displacement of the drill footage reaches 0.0603 mm,the center point of the rock is destroyed.The stress of the rock under the spinning is five times that of the static pressure.The effective transfer range of the axial stress of the rock is 16 mm.The radial stress is symmetrically distributed.The minimum stress at the center point is 17.74~23.55 MPa,and the peak value is 51.31 MPa at the 0.533 times the stress radius,which is about two-thirds of the compressive strength of sandstone.It provides a theoretical basis for the evaluation of wear resistance and drillability of cylindrical flat-bottom rigid bit in rotary drilling of rocks.