
Concept explainers
(a)
Find the expected primary consolidation settlement.
(a)

Answer to Problem 11.6P
The expected primary consolidation settlement
Explanation of Solution
Given information:
The compression index
The thickness of the clay layer (H) is 4 m.
The average permanent load on the clay layer
The average effective overburden pressure
The initial void ratio
Calculation:
Determine the maximum primary consolidation settlement caused by the structural load
Substitute 0.5 for
Therefore, the expected primary consolidation settlement is
(b)
Find the pre-compression time.
(b)

Answer to Problem 11.6P
The pre-compression time
Explanation of Solution
Given information:
The average permanent load on the clay layer
The average effective overburden pressure
The surcharge load per unit area
The coefficient of consolidation
The thickness of the clay layer (H) is 4 m.
Calculation:
Determine the ratio of
Substitute
Determine the value of
Substitute
Refer Figure 11.6, “Plot of U against
For
The degree of consolidation is
Refer Figure 11-8, “Plot of mid plane degree of consolidation against
For
The time factor is
Determine the pre-compression time
Here,
Here, the drainage is two-way. Therefore,
Substitute 0.45 for
Thus, the pre-compression time is
(c)
Find the surcharge pressure that would eliminate the primary consolidation settlements beyond the preloading period.
(c)

Answer to Problem 11.6P
The surcharge pressure that would eliminate the primary consolidation settlements beyond the preloading period is
Explanation of Solution
Given information:
The coefficient of consolidation
The required time (t) is 6 months.
The thickness of the clay layer (H) is 4 m.
The average permanent load on the clay layer
The average effective overburden pressure
Calculation:
Determine the time factor using the formula:
Substitute 6 months for
Refer Figure 11-8, “Plot of mid plane degree of consolidation against
For
The value is
Determine the value of
Substitute
Determine the surcharge pressure using the formula:
Substitute 0.625 for
Simplify the Equation.
Thus, the surcharge pressure that would eliminate the primary consolidation settlements beyond the preloading period is
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Chapter 11 Solutions
EBK FUNDAMENTALS OF GEOTECHNICAL ENGINE
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