ABSTRACT
A review of current design practices for calculating tensile loading during horizontal directional drilling (HDD) installations is provided. These design procedures vary in the ways they treat the basic installation loads such as borehole profile, pipe’s stiffness, frictional drag and fluidic drag. Summarized field data from a recent HDD installation, a 400m double crossing of the Grand River conducted near Brantford, Ontario, is presented. Using the actual profile and parameters of this installation, three representative design approaches are applied and are shown to yield different estimations of the tensile load distribution along the length of the pipe product. A statistical design approach using Monte Carlo simulation is presented where discrete input design parameters are replaced with distributed variables. The potential of the statistical design approach as a tool to aid the HDD designer is demonstrated by applying the simulation technique to produce a CDF plot of the maximum tensile load for a 508mm diameter siphon installed across the Grand River.
