Handbook of Railroad Construction; For the use of American engineers. / Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States.

by George L. Vose

2L = 2w′L′
w

276. Example.—Let the height of wall be twenty feet, slope one and one half to one; if a cubic foot of earth weighs one hundred lbs., and of masonry, one hundred and sixty lbs., we have the overthrowing force,

20 × 15 × 1 × 100 × 2 × 20
3,

and the resisting force, (assuming the thickness as eight feet, in order to get the area),

20 × 8 × 1 × 160 × 8
2.

Or performing the operations,

For overthrowing,	100,000 lbs.
For resisting,	102,400 lbs.

If the wall in place of retaining only the mass B 4 6, retains the bank B E F^a, the pressure will evidently be increased. The centre of gravity of the trapezoid B E F^a 6, is at C′, which is horizontally projected at C′^a, and the horizontal component of the thrust acts at 3 with the leverage 63.

Any superincumbent load, as a train of cars at E F^a, will again increase the pressure, not only by reason of weight, but from shocks and vibration.

For resisting lateral pressure, the beds of masonry are best when rough dressed. For vertical loads, hammer dressed beds are the best.