Core Process Analysis of Deviation Correction for Rotary Drilling Rigs

    During the drilling operation of a rotary drilling rig, it is prone to deviation from the hole due to geological conditions, operating standards, equipment status, and other factors. If not corrected in a timely manner, it can lead to excessive verticality of the pile body, insufficient bearing capacity, and even safety hazards such as hole collapse and drill pipe damage. Deviation correction should follow the principles of "prevention first, precise guidance, scientific correction, and cautious re drilling", and be proficient in guiding control, correction operation, and re drilling technology to ensure the quality of pile foundation construction and improve operational efficiency.

    Guidance control is the foundation for preventing and reducing deviated holes, and the core is to ensure that the drill rod is vertical and the drill bit is evenly stressed during the drilling process. Before starting the homework, it is necessary to level the site, calibrate the levelness of the drilling rig, check the verticality and integrity of the drill rod and drill bit, and avoid deviation caused by equipment placement skewness or drilling tool deformation. In the early stage of drilling, a low-speed light pressure drilling mode is adopted, and the direction of the drill rod is precisely controlled by the guide frame. The verticality data of the drilling instrument panel is observed in real time, and the position of the drilling rig is checked every 1-2 meters to ensure that the drill rod always coincides with the design centerline of the pile hole. For complex geological conditions such as uneven hardness and inclined rock layers, guide casing can be laid in advance to enhance the stability of drill pipes and avoid the risk of deviated holes from the source.

    Scientific correction is the key to solving the problem of deviated holes, and it is necessary to choose appropriate methods based on the degree of deviated holes and geological conditions to avoid blindly operating and exacerbating hidden dangers. If the deviation of the hole is small (deviation ≤ 5cm), the "gradual correction method" can be used to adjust the angle of the drilling rig mast, tilt the drill rod in the opposite direction of the deviation, maintain low-speed and light pressure drilling, review the deviation of the hole every 30-50cm, gradually correct the verticality of the pile hole until the deviation meets the specification requirements. If the deviation of the hole is large (deviation>5cm), the "backfill correction method" should be used to stop drilling, and a mixture of clay and gravel should be backfilled into the pile hole to 1-2 meters above the deviation position. After compaction, the drilling should be resumed at low speed, and the support of the backfill material should be used to guide the drill rod back to the correct direction. During the correction process, it is strictly prohibited to lift or place the drill rod abruptly or adjust the angle sharply to prevent the collapse of the hole wall.

    The re drilling process is suitable for situations where the deviation of the hole is severe, the correction is ineffective, or the inner wall of the pile hole collapses and the hole diameter is irregular. The core is to ensure that the quality of the pile hole meets the standard after re drilling. Before re drilling, it is necessary to thoroughly clean the collapsed objects and debris inside the pile hole, check the integrity of the drilling tools, replace severely worn drill bits and rods, and recalibrate the levelness and guiding device of the drilling rig. When re drilling, adopt the "slow drilling and slow advance" mode, strictly control the drilling speed and pressure, strengthen the frequency of verticality review, focus on the drilling status of the deviated hole part, and adjust the operating parameters in a timely manner. After the re drilling is completed, a comprehensive inspection of the verticality and aperture of the pile hole is required to ensure compliance with design specifications and construction requirements before proceeding to the next process.

    The core of hole deviation correction for rotary drilling rigs is "precise control, gradual progress", with guidance, correction, and re drilling processes interlocked and indispensable. Standardizing the implementation of various processes can effectively solve the problem of deviated holes, ensure the quality of pile foundation construction, reduce equipment loss, avoid safety accidents, improve the stability and efficiency of rotary drilling rig operations, and lay a solid foundation for pile foundation construction in infrastructure projects.