Modified Iowa Formula for Vertical Deflection of Buried Flexible Pipe

Abstract

In this paper, the classical work of Spangler is revisited to derive a modified Iowa formula for estimating vertical deflection of flexible pipe. During the derivation process, the approach suggested by Spangler is faithfully followed. No new assumptions or empirical elements are introduced beyond those originated by Spangler. Once the vertical deflection formula is established, its reliability is verified against field deflection measurement data supplied by Spangler. Then, a few parametric studies are conducted using the horizontal and vertical deflection modified Iowa formulas to gain further insights into the pipe-soil interaction problem as revealed by the work of Spangler. Finally, the paper concludes by offering a summary and then pointing out a few key issues that need to be remembered when applying the classical approach pioneered by Spangler.