Engineering Rock Mechanics

302 Foundation and slope instability mechanisms

the influence of each of the four rectangular areas explicitly, rather than
computing a single quadrant and multiplying the result by 4. Plots of
these distributions are shown below.

477.8 The expression for the radial stress induced beneath a line

load of magnitude P acting normal to the surface of a semi-infinite

half space is

2P sin 6

nr

ur = -.

(a) Show on a sketch the geometry of this problem, indicating

clearly the angle 6 and the orientation of the stress components uo

and ur. What are the magnitudes of

(b) Sketch the locus of constant ur for varying 6, and show how

the expression above leads to the concept of a 'bulb of pressure'.

For the case when the applied line load is not normal to the surface,

show on a sketch how the bulb of pressure changes its nature,

indicating clearly any zones where tensile radial stresses may be

induced.

and tre in this problem?