Numerical Study of Restrained Joint and Pulling Load for Ductile Iron Pipe in Horizontal Directional Drilling

Abstract

As an alternative pipe material, ductile iron pipe (DIP) has been more and more widely used in horizontal directional drilling (HDD) because of its excellent mechanical performance and corrosion resistance. The limited capacity of restrained joints to withstand pulling force severely constrains their application in long-distance crossing projects. The finite-element method (FEM) was used to study the mechanism of joint failure as well as the effect of slope angle, based upon which an approximate solution was developed to estimate the maximum pull capacity of joints. The authors found that joint failure started from the spigot and an appropriate increase of slope angle could improve the maximum pull capacity of joints. Considering pipe angular deflection, a new pullback load estimation model was established and its accuracy was verified by a HDD river crossing project.