300 Foundation and slope instability mechanisms
for a range of aperture values and plotting the results:
012345678
Aperture, mmThe engineering significance of this result is that, unless we have total
confidence in our assessment of the aperture of BD, we should assume
that it is much greater than 1 mm, and accept that the slope as currently
configured has a factor of safety of about 0.44.417.7 A rectangular foundation base, 6 m x 10 m in plan, carries a
vertical load of 180 MN which it transmits to the rock as a uniform
bearing pressure. The rock can be taken to be CHILE, with a modulus
of elasticity E = 800 MPa and Poisson's ratio u = 0.2.
Ignoring the weight of the rock, evaluate the vertical settlement
at the centre, C, of the base and the vertical stress at a point 5 m
below C.A17.7 The loaded area we are ana-
lysing is shown to the right.
The solution to problems involving
loaded areas on CHILE foundations
can be found from application of the
integral form of the Boussinesq equa-
tions. However, these equations are
defined over one quadrant, with the
point of interest being at some depth
on the z-axis. As a result, we can only apply the equations over one
quarter of the loaded area, as follows:total load of 180MN,total load of
Integral form of Boussinesq 45MN, uniformly
equations applicable to one distributed
quadrant