According to the analysis, since the shear stress of rock is smaller than the compressive stress and tensile stress, it is considered that the main failure mode of rock bottom hole is shear failure or tensile stress failure. Therefore, the maximum principal stress of rock is mainly considered in the analysis. In order to analyze the impact of impact load on rock breaking efficiency, according to the impact frequency analysis results, the influence of different bit weight on rock principal stress under the condition of axial impact or not is analyzed. During the drilling process of diamond composite pdc bit, a large principal stress appeared around and at the bottom of the hole, indicating that the stress around the hole wall would be increased during drilling. The greater the weight on bit, the greater the corresponding rock principal stress.
By comparison, it is found that the principal stress of rock under impact load is obviously greater than that under no impact load, and the corresponding principal stress of rock will increase with the increase of bit weight. In order to analyze the influence of rotational speed on rock breaking efficiency of diamond composite pdc bit, under the same bit weight, applying different rotational speed to diamond composite pdc bit can obtain the rock principal stress of diamond composite pdc bit under the condition of axial impact or not. As the rotational speed of diamond composite pdc bit increases, the corresponding rock principal stress will also increase. And the impact load condition can increase the principal stress of rock.
The above is the analysis of the influence of drilling parameters of diamond composite pdc bit on rock stress.
