刘伟吉, 王燕飞, 郭天阳, 罗云旭, 祝效华. 单齿切削破碎非均质花岗岩微宏观机理研究[J]. 工程力学, 2022, 39(6): 122-133. DOI: 10.6052/j.issn.1000-4750.2021.03.0213
引用本文: 刘伟吉, 王燕飞, 郭天阳, 罗云旭, 祝效华. 单齿切削破碎非均质花岗岩微宏观机理研究[J]. 工程力学, 2022, 39(6): 122-133. DOI: 10.6052/j.issn.1000-4750.2021.03.0213
LIU Wei-ji, WANG Yan-fei, GUO Tian-yang, LUO Yun-xu, ZHU Xiao-hua. INVESTIGATION ON THE ROCK CUTTING MECHANISM OF HETEROGENEOUS GRANITE USING A GRAIN-BASED MODELING APPROACH[J]. Engineering Mechanics, 2022, 39(6): 122-133. DOI: 10.6052/j.issn.1000-4750.2021.03.0213
Citation: LIU Wei-ji, WANG Yan-fei, GUO Tian-yang, LUO Yun-xu, ZHU Xiao-hua. INVESTIGATION ON THE ROCK CUTTING MECHANISM OF HETEROGENEOUS GRANITE USING A GRAIN-BASED MODELING APPROACH[J]. Engineering Mechanics, 2022, 39(6): 122-133. DOI: 10.6052/j.issn.1000-4750.2021.03.0213

单齿切削破碎非均质花岗岩微宏观机理研究

INVESTIGATION ON THE ROCK CUTTING MECHANISM OF HETEROGENEOUS GRANITE USING A GRAIN-BASED MODELING APPROACH

  • 摘要: 深部难钻地层岩石硬度大、可钻性差等问题是制约深层非均质硬地层钻井提速的瓶颈问题,深入研究其切削破碎机理对于提高钻进速度、降低钻井成本有重要意义。该文采用离散元PFC2D—GBM (Particle Flow Code 2D—grain-based model)来模拟硬脆性的非均质花岗岩,研究了不同液柱压力、晶粒尺寸、晶粒随机分布特性、钻齿倾角、切削深度和速度等条件下的单齿切削破碎花岗岩机理。研究发现:晶间剪切裂纹和晶内拉伸裂纹是切削过程中花岗岩产生的两种主要裂纹类型;切削力随着切削行程表现出明显的波动,切削力大小急剧增大和降低,并且随着液柱压力、切削深度和切削齿倾角的增大表现得更加明显;液柱压力、晶粒尺寸和晶粒的随机分布特性对切屑形态有很大影响,相比之下,与上述三个因素相比,切削深度、刀具前角和切削速度对切屑形态影响不大。研究结果对于深入认识花岗岩切削破碎机理有重要意义,可为改进破岩钻头的设计提供依据。

     

    Abstract: A good understanding of rock cutting mechanism is of great importance for improving the cutting efficiency and reducing the costs in hard heterogeneous formation drilling. Implements the grain-based modeling approach to mimic the granite considering the highly heterogeneous mechanical behaviors of grains in granite. The rock cutting mechanism of granite, accounting for the influence of hydrostatic pressure, mineral size, random distribution, rake angle, cutting depth and velocity of cutter, are investigated. The research results demonstrate that the inter-grain shear crack and intra-grain tensile crack are the two main crack types generated during rock cutting process. The cutting force responses show strong vibration with respect to the cutting distance. The magnitude of cutting force sharply drops and abruptly rises during the cutting process, which becomes more obviously with the increasing hydrostatic pressure, cutting depth and rake angle of cutter. The hydrostatic pressure, grain size and random distribution of grains have great influence on chip morphology. In contrast, comparing with the above three factors, the cutting depth, rake angle of cutter and cutting velocity have little influence on the chip morphology. These results lead to an enhanced understanding of rock breaking mechanisms in granite, and provide a basis for improving the design of rock-breaking bits.

     

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