Analysis of the Pipeline Pull-back Load for Horizontal Directional Drilling

One of the major areas of research in Horizontal Directional Drilling (HDD) technology is the accurate prediction of the pipeline pull-back load, which influences the project design schemes, selection of the drilling rig type and the mechanism of pull-back for reducing resistance. In this study, the possible contact state between the pipe and the hole is analysed based on the force exerted by the pipe in the circular sector of the hole, and the pull-back resistance of the pipe is calculated according to the bending beam theory. The full-scale model of the pipeline pull-back is established using numerical methods, the results of which are then compared to those obtained in the field test. In the numerical analysis, the resultant force of the mud buoyancy and pipeline gravity is substituted with an equivalent gravitational acceleration in the vertical direction. The results show that the pull-back force is not uniform when the pipe has just entered the hole. When the pull-back load is stabilised, the pull-back force of the pipeline is appropriately linear. After the pipe enters the hole, the variation curve of the pull-back force depends on the various values of the equivalent gravitation acceleration.