Civil Engineering Reference
In-Depth Information
stress and lack of free-floating slab elements, this type of foundation will probably perform
even better during an earthquake than the conventional slab-on-grade.
13.5 PROBLEMS
13.1
Use the data from Prob. 9.11 and Fig. 9.38 and assume a level-ground site. A pro-
posed building will have a deep foundation system consisting of piles that are driven into the
Flysh claystone. Assuming that the piles are widely spaced and do not increase the liquefaction
resistance of the soil, calculate the differential movement between the building and adjacent
ground.
Answer:
Using Fig. 7.1, differential movement
20 cm. Using Fig. 7.2, differential
movement
14 cm.
13.2
Use the data from Prob. 13.1 and an effective friction angle
between the pile sur-
face and the surface soil layer and sand layer of 28
. Assume that
k
0
0.5 and that the last
location for the earthquake-induced pore water pressures to dissipate will be just above the
clayey fine sand layer. Further assume that the clayey fine sand layer and the silty fine sand
layer are not anticipated to settle during the earthquake. If the piles are 0.3 m in diameter, cal-
culate the downdrag load on each pile due to liquefaction at the site.
Answer:
Downdrag
load
61 kN.
13.3
Use the data from Prob. 6.12 and Fig. 6.13. To prevent liquefaction-induced set-
tlement of the building, what is the minimum length of piles that should be installed at the
site?
Answer:
20-m-long piles.
FIGURE 13.38
Construction of a posttensioned foundation for a single-family residence.
