On the capillary forces in an ideal soil; correction of formulae given by W. B. Haines

TLDR

Haines’ formulae omitted air‑water interface tension, introducing erroneous factors and additional errors in average stress expressions. The authors corrected Haines’ formulae, showing moisture stress changes little with water content, used a geometrical approximation that fits the figure but is mechanically less accurate, and supplied numerical data for the true curve and necessary tables. Rupture energy increases continuously, resembling Haines’ measurements, and is likely more relevant than tensile stress. References 1–3 are cited.

Abstract

1. The omission of the tension in the air-water interface has introduced an erroneous factor into Haines’ formulae; certain additional factors have also crept into his expressions for average stress. 2. With these corrections, the stress due to moisture varies comparatively little with changing water content, though falling slightly throughout the range. The energy needed to cause rupture rises continuously in a manner not unlike Haines’ measurements, and should more probably be associated with them than should the tensile stress. 3. The geometrical approximation used by Haines gives a close geometrical representation of the figure, but a mechanical approximation which is less satisfactory. Since neither the formulae connected with the true curve, nor the tables needed to use them, are readily, accessible, sufficiently exact numerical data have been here put on record.