472 Questions^7 7.7-7 7.70: foundation and slope instability mechanisms
(b) Sketch the locus of constant a, for varying 8, 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.
(c) This analysis is for CHILE materials. By making use of the @,
theory, show qualitatively how the bulb of pressure may be expected
to change when the ground beneath the load consists of a layered
discontinuous rock mass dipping at some arbitrary angle.
(d) On the basis of these results, what are the ramifications this
analysis has for site investigation in layered rocks?
417.9 The system of rock blocks shown in the sketch below is to be
used in the verification procedure of a computer code for analysing
progressive failure of rock slopes, and for this a manually derived
solution is required.The system is in limiting equilibrium with block A tending to topple
about the corner C, while block B is on the point of sliding downhill. The
shear resistance on all surfaces is purely frictional with @ = 35".
Given that B is twice as heavy as A, determine the thickness t of block
B. Also show that there is no tendency for block A to slip at the comer C.417.10 Solve Q17.5 numerically using the sector method, and comment
on any discrepancies between the numerical solution and the analytical
solution.