Horizontal directional drilling influence on the behaviour of polyethylene pipes

Horizontal directional drilling (HDD) is the primary trenchless technology research focus at the University of Waterloo. The HDD pipe installation process consists of three stages, the pilot hole, back reaming, and pipe installation (Figure 2). The pilot hole consists of drilling a pre-planned hole, typically 100 to 150 mm in diameter, using a horizontal directional drill and drilling fluids. At the completion of the pilot hole, the drill head exits the ground surface. The back reaming stage consists of removing the pilot hole drill head and installing a back reamer head that has a diameter larger than the pilot hole. The back reamer is then rotated and pulled back towards the drill rig to enlarge the bore hole. The bore path may be back reamed with multiple reamer passes or different reaming heads depending on site soil conditions, drill path length, or the pipe size to be installed. The pipe is installed by attaching the pipe to the back reaming head, using a swivel and pulling it towards the drill rig. For short bore path lengths and small diameter pipes, back reaming and pipe installation stages may be combined into a single stage.

Our research objective is to advance the understanding of the behaviour horizontal directional drilled polyethylene pipes (PE). The long term goal of this research program is to provide data that will help with the development of rational HDD design guidelines and installation specifications. The research objective and goal will be accomplished by:

1) developing numerical simulation techniques that simulates the behaviour of HDD installed PE pipes;

2) complete research into drilling fluid-PE pipe interaction;

3) monitor HDD install PE pipes under controlled field conditions.