Civil Engineering - UPSC Civil Service Exam Questions - Discussion

Discussion Forum : UPSC Civil Service Exam Questions - Section 6 (Q.No. 37)
37.
A soil fails under an axial vertical stress of 100 kN/m2 in unconfined compression test. The failure plane makes an angle of 50° with the horizontal. The shear parameters c and φ respectively will be
41.9 kN/m2, 0
50.0 kN/m2, 0
41.9 kN/m2, 10°
50.0 kN/m2, 10°
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
11 comments Page 1 of 2.

Gabi said:   6 years ago
α= 45° + φ/2.
50=45 + φ/2.
φ/2 = 5, φ = 10.
(1)

Riya said:   6 years ago
In UCS test,
σ1 = σ3 * tan^2 α + 2c tan a
But σ3 = 0
So the equation will be,
σ1 = 2c tan a.

Now, a =45° + π/2.
So, a = 45° + 10°/2.
a=50°.

Now,
σ1 = 100 kN /m^2.

100= 2c tan (50°).
So, c= 41.9 kN /m^2.
And π = 10°.
(1)

Rahul verma said:   2 years ago
(&sigma)1 = (sigma)3 * tan^2(50) + 2Ctan50.

(&sigma)3=0 for the unconfined compression test.

(σ)1=2Ctan50.
C=100/2tan50,
C=41.9.

The failure plane angle = 45+x/2.
50=45+x/2
X=10
(1)

Apurbajyoti Neog said:   2 years ago
In the case of unconfined compression test Cohesion (C) = Qu/2=100/2 = 50 KN per square metre.
(1)

Amith S said:   7 years ago
The Answer should be B.

Sandy said:   7 years ago
I think the answer should be D.

Saurabh said:   6 years ago
σ 1 = σ 3 X (tan α) + 2c tan α.
Α = 50 °...σ 3 = 0 (because unconfined).

Hence σ1 = 2C tan α = 100.
Hence c = 41.9π = 10 °.

Triza said:   6 years ago
How did you get the angle of resistance? @Saurabh.

Jadeja said:   6 years ago
How did you get an angle? Please explain.

Showkat said:   5 years ago
In an unconfined compression test c=sigma/2.
a=45+phi/2.


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