[Footnote 15:] Given in detail in “The Design of Walls, Bins and Grain Elevators,” by Milo S. Ketchum, M. Am. Soc. C. E.] [Return to text]
[Footnote 16:] Ketchum’s “Walls, Bins, and Grain Elevators,” Fig. 171.] [Return to text]
[Footnote 17:] “Traité de Stabilité des Constructions,” p. 292; see also Remark at end of Appendix.] [Return to text]
[Footnote 18:] Scheffler has not noted this fact, and consequently some of his deductions are open to objections. His theory, involving cohesion, is the only one the writer has seen.] [Return to text]
[Footnote 19:] “The Design of Walls, Bins and Grain Elevators,” Chapter XVI.] [Return to text]
[Footnote 20:] It may be well to remark here, that for cohesive earth, it has been proved, both theoretically and experimentally, that the surface of rupture is curved, and not a plane, as the theory assumes. However, assuming it to be a plane, and considering successive wedges of rupture of different heights, the bases of which lie on the same plane, it can be easily shown that certain of the upper wedges can be sustained by cohesion alone, and that the coefficient of cohesion required for stability varies from 0 at the surface to its maximum value at a certain depth,
. Below this depth, friction in addition to cohesion is exerted, and stability is assured if we suppose the friction coefficient to increase from 0 at
to its maximum value,