1
Civil & Environmental Engineering Department
Mid-term 1 Review
Please prepare for:
 all questions that I solved in class (see PowerPoint slides)
 all homework problems
 the question listed here
 Questions from Course Pack
Question pattern:
Shallow Foundation Design
70
Soil Exploration
20
ASCE Procedure for depth of boring
10
1.
2
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3
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2.
Shown in the figure are the plan and cross section of a column and its foundation.
Geotechnical investigation revealed the following soil properties:
For silty sand:  = 100 pcf
sat = 120 pcf
Es = 3200 psi
Poisson’s ratio = 0.3
’ = 240
c’ = 0.4 tsf
For Clay:
sat = 118 pcf
Es = 1200 psi Poisson’s ratio = 0.5
0
’ = 0
c’ = 1.25 tsf
a)
Please calculate the allowable load that the foundation can carry for a
factor of safety of 3.
b)
Please calculate the elastic settlement of foundation, if the total load (Q)
on the column is 450 kips.
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a)
Civil & Environmental Engineering Department
b)
Elastic Settlement on Sand
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Elastic Settlement on Clay
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3.
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4.
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5.
Shown in the Figure is plan and cross-section of a two story building proposed to be constructed over
ocean floor. The depth of ocean floor is 4 ft. below the water level. The load in all columns are equal
and are 200 kips. The soil profile shows two layers of sand above the bed rock properties of which are
shown in Table 1. The area is well protected with tide fences so that there is no horizontal thrust
induced by the tide water. Assume the specific gravity of ocean water as 1.03 and factor of safety of 4.
Depth of the footing is 3 ft. The allowable total settlement is 1 inch with the differential settlement of
0.25 inch. Make necessary assumptions in case the required information is not provided.
Table 1 Properties of sand layers
Soil Type
Saturated unit
weight (pcf)
Friction angle
(degree)
Poisson’s ratio
Modulus of
elasticity (ksf)
Sand Layer A
118
30
0.3
900
Sand Layer B
125
34
0.4
1200
Y
X
a. Please calculate the bearing capacity of the soil and the size of the footing from the bearing capacity
criteria.
b. Please calculate the size of footing from bearing capacity point and settlement criteria. The total
settlement should not exceed 25 mm and the differential settlement should not exceed 10 mm.
c. Please design the foundation system for the loading presented above for a base seismic coefficient
of 0.3.
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C)
Resisting Force = Q x tan 
Driving Force = k x Q
= 200 x tan (0.67x30)0
= 0.3 x 200
FS = Resisting Force/Driving Force
= (200 x tan (0.67x30 0)/ (0.3 x 200)
= 1.21 > 1.1
Therefore, the foundation is safe against seismic loading.
Civil & Environmental Engineering Department
6.
Column loads shown in the following figure are supported by a mat foundation, shown below.
The properties of the clay layers are shown below. Ground water table is at the base of the mat.
Pre consolidation pressure of the soil on the ground surface is 500 kPa. Cc and Cr of both clays
are 0.9 and 0.15, respectively. Initial void ratios of the first and second layers are 1.0 and 0.7,
respectively. Please calculate the total consolidation settlement.
Civil & Environmental Engineering Department