Fundamentals of Geotechnical Engineering (MindTap Course List)
Fundamentals of Geotechnical Engineering (MindTap Course List)
5th Edition
ISBN: 9781305635180
Author: Braja M. Das, Nagaratnam Sivakugan
Publisher: Cengage Learning
Question
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Chapter 12, Problem 12.1P

(a)

To determine

State whether the statement “thinner the wall, the higher is the area ratio of a sampling tube” is true or false.

(a)

Expert Solution
Check Mark

Answer to Problem 12.1P

The given statement is False_.

Explanation of Solution

Show the expression for the area ratio.

AR(%)=Do2Di2Di2AR(%)Do2Di2

Here, AR is the area ratio, Do is the outside diameter, and Di is the inside diameter of the sampler tube.

As per the formula, the area has the direct proportional relationship with the value of Do2Di2.

The formula denotes if the wall thickness of the sampling tube is high, the area ratio will be higher and vice versa.

Hence, the given statement is False_.

(b)

To determine

State whether the statement “samples recovered from the split-spoon samplers are highly disturbed” is true or false.

(b)

Expert Solution
Check Mark

Answer to Problem 12.1P

The given statement is True_.

Explanation of Solution

Split-spoon samplers are used to obtain representative samples suitable for the field examination of soil texture and fabric. The samples obtained by this process are highly disturbed.

Hence, the given statement is True_.

(c)

To determine

State whether the statement “N60 is greater than N70 in a standard penetration test” is true or false.

(c)

Expert Solution
Check Mark

Answer to Problem 12.1P

The given statement is True_.

Explanation of Solution

Express the relationship between standard penetration numbers N60 and N70.

N70=N60×60%70%=N60×0.60.7=N60×0.86

In N60, 60 denotes 60 % hammer efficiency and in N70, 70 denotes the 70 % hammer efficiency.

Thus, the value of N70 is only 0.86 times the value of N60. Thus, N60 value is larger than the value of N70.

Hence, the given statement is True_.

(d)

To determine

State whether the statement “N60 can be greater or less than (N1)60 in a standard penetration test” is true or false.

(d)

Expert Solution
Check Mark

Answer to Problem 12.1P

The given statement is True_.

Explanation of Solution

Express the relationship between the effective overburden pressure (N1)60 and N60.

(N1)60=CNN60

Here, CN is the correction factor.

The value of CN<1 results in (N1)60<N60.

The value of CN>1 results in (N1)60>N60.

The value of CN=1 results in (N1)60=N60.

Hence, the given statement is True_.

(e)

To determine

State whether the statement “vane shear test can be carried out in sands” is true or false.

(e)

Expert Solution
Check Mark

Answer to Problem 12.1P

The given statement is False_.

Explanation of Solution

The un-drained shear strength of soft clay is estimated directly by the Vane shear test. Reliable results only in medium stiff clays and soft clays are obtained from the field vane shear test.

Vane shear test is valid for only cohesive soil and it is not suitable for clays which contain sand or silt laminations in it.

Hence, the given statement is False_.

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Students have asked these similar questions
A= 25 B= 75 C= 5 D= 45 E= 85 F= 8
The unconfined compression test sampler is : Split Spoon sampler   Sonotube sampler   Shelby tube sampler
Please explain clearly..... Thank you
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