The Horizontal Directional Drilling Pipe Vibration Characteristic Research

As the main consumable material in horizontal directional drilling, the drill pipe is usually rotating and drilling in a variety of soil layers with completely different mechanical properties, bearing loads like tension, pressure, bending moment, torque, vibration and impact. These loads make every pipe under extreme mechanical stress state and easy to appear fatigue failure. The failure means great financial losses to the construction units and the main reason is vibration. In this paper the vibration performance of the drill pipe was studied using finite element analysis software-ANSYS. The main contents and conclusions are as following:1) The finite element model of the drill pipe in deflecting interval which beared the most complex force was built and the statics analysis was carried out to find the distribution rule of stress on pipe and the influence law of the curvature radius of deflecting interval on stress, the results showed the stress concentration area existed in the contact part of drill pipe joint and soil, and the increasing of curvature radius would cause the decreasing of the maximum stress of pipe.2) The transverse, longitudinal and torsional vibration of the drill pipe was analyzed separately to get the influence law of different factors including the curvature radius of deflecting interval, the length of horizontal section, the specification, the thrust and pull on natural frequency of these different vibrations, the results showed that the increasing of length of horizontal section and the thrust and pull would cause the decreasing of natural frequency of these different vibrations, the increasing of curvature radius would cause the decreasing of natural frequency of the transverse vibration and the increasing of specification would cause the increasing of natural frequency of the transverse vibration.3) The application of vibrations characteristics of the drill pipe was disscussed in an engineering example; it showed that the increasing of curvature radius of deflecting interval and specification could both avoid the transverse resonance of the drill pipe. The results of the drill pipe vibrations study could provide guidance in speed optimization and designing the borehole trajectory in engineering construction.4) The experiment was designed to measure the natural frequency of the transverse vibration of a cantilever steel tube, through comparing the results with simulation results, the analysis models of drill pipe were verified to be correct.