Predictive modeling of installation loads for directional drilled fusible PVC pipe

Today, trenchless technologies such as horizontal directional drilling (HDD) have increased significantly as an alternative installation method in the municipal sector. Installation of potable water, force mains, reclaimed water, and gravity sewer pipelines employing directional drilling have increased as demand for installations in difficult areas including under rivers or major highways and highly urbanized and congested utility corridors has increased. The nature of the HDD process necessitates the use of continuously joined pipe products capable of being pulled in, as opposed to being pushed, or “jacked” in as with segmental installations. Fusible polyvinylchloride pipe (FPVCP) is one such material for installation of water and wastewater, pressure and non-pressure infrastructure using HDD. This paper describes a model for predicting pull loads during HDD installations using FPVCP. Pull load data was captured using an in-line measuring device attached between the backreamer of the drill string and the product pipe to gauge exact loading transferred to the pipe. Detailed results from four field projects demonstrate excellent correlation between predicted and field data.