FOOTINGS AND PILE FOUNDATIONS - Introduction to Soft Soil Geotechnique: Content, Context and Application - page 207

application 12.7
A concrete pile of 25 m length and equivalent diameter of 40 cm is driven into
the soil until end-bearing is achieved in a deeper sand layer. On top the soil is soft
with unit weight 18 kPa/m and undrained strength of 50 kPa. The CPT of the sand
is 20 MPa. Determine the total bearing capacity of the pile. Is it wise to include
shaft friction and which safety factor would you suggest. So, finally what is the
design value for the bearing capacity?
application 12.8
The foundation of a strip footing with width 3 metres can be designed with
Prandtl's solution. The footing is placed 2 metre under the soil surface. The
undrained strength of the soil is 25 kPa and the unit weight is 14 kPa/m. What is
the bearing capacity q ? Note that q 0 is not zero! What controls the Prandtl wedge
being at the left or at the right side? If the strip footing is not long, dimensional
effects play a role. Does the bearing capacity increase or decrease under three-
dimensional effects?
application 12.9
In soft soil regions pile foundations support buildings, the older buildings on
traditional wooden piles. When the road in front is raised to compensate for the
compaction of the underground, the added sand weight may exert a horizontal
pressure on these piles. In the end, the piles may be pushed aside from the walls
they should support. As a consequence severe settlement may occur (Fig 12.10).
Which possible measure could be taken to prevent this from happening?
Figure 12.10