Mechanical modelling for pipes in horizontal directional drilling

Abstract

This paper presents a new technique to predict forces and deformations of pipes installed underground by horizontal directional drilling (HDD). The proposed technique consists of several models each describing different aspects of mechanics of HDD. It allows prediction of the shape of the pipe in the borepath. Based on the pipe shape, shape of the borepath and pipe stiffness, the contact forces between the pipe and the borepath are calculated. The contact forces cause friction and thus axial pulling force is induced to equilibrate the frictional forces and the weight of the pipe. The analytical model is used to study the stresses and strains on two pipes that were tested in the field. The theoretical results are compared with the strains measured in the field.