CE 442 Exam 2 questions with
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answers
When a deep foundation is used to support a structure in
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expansive soil and the soil becomes wet, what problem |\ |\ |\ |\ |\ |\ |\ |\ |\
should the design consider? - CORRECT ANSWERS
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✔✔Expansive soil may swell and exert an upward friction |\ |\ |\ |\ |\ |\ |\ |\ |\
on the deep foundation which must be resisted to prevent
|\ |\ |\ |\ |\ |\ |\ |\ |\
heave.
|\
List two reasons why deep dynamic compaction is
|\ |\ |\ |\ |\ |\ |\ |\
desirable for treating collapsible soils in comparison with |\ |\ |\ |\ |\ |\ |\ |\
conventional excavation and re-compaction. - CORRECT |\ |\ |\ |\ |\ |\
ANSWERS ✔✔1. Can treat 30 ft or more when excavation |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
would be problematic |\ |\
2. Less expensive than excavate & replace
|\ |\ |\ |\ |\ |\
3. Faster and more efficient
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What is the difference between the modulus of subgrade
|\ |\ |\ |\ |\ |\ |\ |\ |\
reaction and a soil spring? - CORRECT ANSWERS |\ |\ |\ |\ |\ |\ |\ |\
✔✔Modulus, Ks is q/y with units of force/cubic length |\ |\ |\ |\ |\ |\ |\ |\
Spring stiffness, is the Ks multiplied by the area of the
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
footing involved. |\
, The eccentricity of the loading exceeds L/6 for a spread
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
footing what effect does this have on the pressure on the
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
base of the footing? - CORRECT ANSWERS ✔✔It puts part
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
of the soil under tension, but soil can't handle tension for
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
long so it ends up increasing the compressive stress over
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
only part of the footing
|\ |\ |\ |\
Under what conditions is one-way or wide-beam shear
|\ |\ |\ |\ |\ |\ |\ |\
likely to control the thickness of a spread footing? -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔footing with high overturning |\ |\ |\ |\ |\ |\
moment
rectangular footing |\
Wick drains create a suction which causes clay to
|\ |\ |\ |\ |\ |\ |\ |\ |\
consolidate? - CORRECT ANSWERS ✔✔False |\ |\ |\ |\
A soil profile will usually settle faster if subject to a large
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
area load of 1000 psi than if subjected to a 1000 psi
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
pressure under a 10ft x 10ft footing. - CORRECT |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔False |\
Typically, consolidation time decreases as the wick drain |\ |\ |\ |\ |\ |\ |\ |\
spacing decreases, but at small drain spacings this may
|\ |\ |\ |\ |\ |\ |\ |\ |\
not be true. Explain why this might be the case. -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔As drains are placed closer |\ |\ |\ |\ |\ |\ |\
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answers
When a deep foundation is used to support a structure in
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
expansive soil and the soil becomes wet, what problem |\ |\ |\ |\ |\ |\ |\ |\ |\
should the design consider? - CORRECT ANSWERS
|\ |\ |\ |\ |\ |\ |\
✔✔Expansive soil may swell and exert an upward friction |\ |\ |\ |\ |\ |\ |\ |\ |\
on the deep foundation which must be resisted to prevent
|\ |\ |\ |\ |\ |\ |\ |\ |\
heave.
|\
List two reasons why deep dynamic compaction is
|\ |\ |\ |\ |\ |\ |\ |\
desirable for treating collapsible soils in comparison with |\ |\ |\ |\ |\ |\ |\ |\
conventional excavation and re-compaction. - CORRECT |\ |\ |\ |\ |\ |\
ANSWERS ✔✔1. Can treat 30 ft or more when excavation |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
would be problematic |\ |\
2. Less expensive than excavate & replace
|\ |\ |\ |\ |\ |\
3. Faster and more efficient
|\ |\ |\ |\
What is the difference between the modulus of subgrade
|\ |\ |\ |\ |\ |\ |\ |\ |\
reaction and a soil spring? - CORRECT ANSWERS |\ |\ |\ |\ |\ |\ |\ |\
✔✔Modulus, Ks is q/y with units of force/cubic length |\ |\ |\ |\ |\ |\ |\ |\
Spring stiffness, is the Ks multiplied by the area of the
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
footing involved. |\
, The eccentricity of the loading exceeds L/6 for a spread
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
footing what effect does this have on the pressure on the
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
base of the footing? - CORRECT ANSWERS ✔✔It puts part
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
of the soil under tension, but soil can't handle tension for
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
long so it ends up increasing the compressive stress over
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
only part of the footing
|\ |\ |\ |\
Under what conditions is one-way or wide-beam shear
|\ |\ |\ |\ |\ |\ |\ |\
likely to control the thickness of a spread footing? -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔footing with high overturning |\ |\ |\ |\ |\ |\
moment
rectangular footing |\
Wick drains create a suction which causes clay to
|\ |\ |\ |\ |\ |\ |\ |\ |\
consolidate? - CORRECT ANSWERS ✔✔False |\ |\ |\ |\
A soil profile will usually settle faster if subject to a large
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
area load of 1000 psi than if subjected to a 1000 psi
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
pressure under a 10ft x 10ft footing. - CORRECT |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔False |\
Typically, consolidation time decreases as the wick drain |\ |\ |\ |\ |\ |\ |\ |\
spacing decreases, but at small drain spacings this may
|\ |\ |\ |\ |\ |\ |\ |\ |\
not be true. Explain why this might be the case. -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔As drains are placed closer |\ |\ |\ |\ |\ |\ |\
