# The Lateral Pressure of Earth Against Footings Subject to Over-Turning Moment

*THE USUAL THEORY.-It is usual to estimate the moment of resistance of the lateral pressure of earth against sheet piling and footings by calculation of the passive pressures on each side of the member according to Rankine’s Formula. The full value of passive pressure given by this formula is known to require very considerable movement and only a fraction (n) of it can be allowed.* Fig. 1 shows this method of treatment
of the problem in its simple form applied to a square section pile or pole, where a centre of rotation A is found so as to provide a balance of moments and of horizontal forces. The method suffers from two defects. In the first place it is assumed that the pressure distribution on a tilting surface is the same as it would be on the same surface moving horizontally, whilst in the second place the fraction (n) of Rankine’s value for maximum pressure is a matter of judgment or ignorance.
Arthur A. Fordham*

Author(s): Fordham, Arthur A