Lateral Pressure Surcharge formula ? 1

[Baggins]

Help !

Lateral presssure surcharge formula ?????????

Can some one please tell me where this formula comes from :

((0.28xV)/H^2)x (n^2/((0.16+n^2)^2))

Where H= Depth of wall
n= Critical Depth ??????????
V= Surcharge load

the reference for the formula was "Foundation analysis and design" JE Bowles, but can't find it there.

 

[austim]

Try "Foundation Analysis and design", Joseph E Bowles, Third Edition, (International Student Edition), page 415.

The formula you quote is shown in a numerical example. The fundamental formula is derived from Boussinesq and is shown as eqn (11-19)

 

[DaveVikingPE]

Lateral pressure due to point load surcharge:

sigma-H = .28 X (Q/H^2) X n^2/(.16 + n^2)^3 for m=< .4

It's dependent on the distance from the bulkhead, x, where x = mH, where H = bulkhead height above dredge line.

z = nH, where z is a vertical distance measured from the top of the bulkhead down.

Q = the point load.

The formula will give you a lateral pressure distribution for various values of n. Plot this distribution and calculate a lateral pressure resultant that's added to your active pressures, etc.

The formula, as austim says, is a modification of Boussinesq, after Terzaghi and Teng, et al. Bowles' book is excellent, BTW. You might also look in the Pile Buck Sheet Piling Design Manual (

http://www.pile-buck.com).