Soil Mechanics & Foundation Engineering

Soil Mechanics Quiz | Science Stoppers

1. If the void ratio (e) of a soil sample is 0.5, what is its porosity (n)? यदि मिट्टी के नमूने का रिक्ति अनुपात (void ratio) 0.5 है, तो इसकी सरंध्रता (porosity) क्या है?

A) 0.33
B) 0.50
C) 0.66
D) 0.25

Correct Answer: A
Explanation: Relationship is n = e / (1 + e).
n = 0.5 / (1 + 0.5) = 0.5 / 1.5 = 1/3 ≈ 0.33.

2. Match the following Soil States with their Consistency Indices:
1. Liquid Limit | P. Soil starts crumbling when rolled into 3mm thread
2. Plastic Limit | Q. Soil has practically no shear strength
3. Shrinkage Limit | R. No further volume change on drying मिट्टी की अवस्थाओं का उनके संगत सूचकांकों से मिलान करें:
1. लिक्विड लिमिट | P. 3 मिमी धागे में रोल करने पर मिट्टी टूटने लगती है
2. प्लास्टिक लिमिट | Q. मिट्टी में व्यावहारिक रूप से कोई कतरनी ताकत नहीं होती
3. संकुचन सीमा | R. सुखाने पर आयतन में कोई और परिवर्तन नहीं होता

A) 1-Q, 2-P, 3-R
B) 1-P, 2-Q, 3-R
C) 1-R, 2-P, 3-Q
D) 1-Q, 2-R, 3-P

Correct Answer: A
Explanation: At Liquid Limit, soil behaves like a fluid (zero strength). Plastic limit is defined by the 3mm thread test. Shrinkage limit is the point where soil reaches minimum volume.

3. Assertion (A): Standard Proctor Test uses a heavier rammer than the Modified Proctor Test.
Reason (R): Modified Proctor Test is used to simulate heavier loading conditions of modern aircraft and traffic. कथन (A): स्टैंडर्ड प्रोक्टर टेस्ट में मॉडिफाइड प्रोक्टर टेस्ट की तुलना में भारी रैमर का उपयोग किया जाता है।
कारण (R): मॉडिफाइड प्रोक्टर टेस्ट का उपयोग आधुनिक विमान और ट्रैफिक की भारी लोडिंग स्थितियों को सिम्युलेट करने के लिए किया जाता है।

A) Both A and R are true and R is correct explanation
B) Both A and R are true but R is NOT correct explanation
C) A is false but R is true
D) A is true but R is false

Correct Answer: C
Explanation: Assertion is False. Modified Proctor uses a 4.54 kg rammer, whereas Standard Proctor uses a 2.49 kg rammer. Reason is True.

4. In a falling head permeability test, the time taken for the head to fall from 80cm to 40cm is 10 minutes. How much more time is required for the head to fall from 40cm to 20cm? फालिंग हेड पारगम्यता परीक्षण में, हेड को 80 सेमी से 40 सेमी तक गिरने में 10 मिनट लगते हैं। हेड को 40 सेमी से 20 सेमी तक गिरने में और कितना समय लगेगा?

A) 5 minutes
B) 10 minutes
C) 20 minutes
D) 15 minutes

Correct Answer: B
Explanation: In Falling Head Test, the time intervals for equal head ratios (80/40 = 2, and 40/20 = 2) are equal. Since the ratio is the same, the time will also be 10 minutes.

5. When the water table rises up to the ground surface, the effective stress in the soil: जब जल स्तर (water table) जमीनी सतह तक बढ़ जाता है, तो मिट्टी में प्रभावी तनाव (effective stress):

A) Increases
B) Decreases
C) Remains constant
D) Becomes zero

Correct Answer: B
Explanation: Effective stress σ’ = Total Stress (σ) – Pore Water Pressure (u). As water table rises, ‘u’ increases, thus reducing σ’.

6. A clay layer 4m thick reaches 50% consolidation in 100 days. How long will it take for a similar 8m thick clay layer (with same drainage) to reach 50% consolidation? 4 मीटर मोटी मिट्टी की परत 100 दिनों में 50% समेकन (consolidation) तक पहुँचती है। 8 मीटर मोटी वैसी ही परत को 50% समेकन तक पहुँचने में कितना समय लगेगा?

A) 200 days
B) 400 days
C) 100 days
D) 800 days

Correct Answer: B
Explanation: Time t ∝ H².
If thickness doubles (4m to 8m), time becomes 2² = 4 times.
100 × 4 = 400 days.

7. The ratio of Active Earth Pressure ($K_a$) to Passive Earth Pressure ($K_p$) for a soil with φ = 30° is: φ = 30° वाली मिट्टी के लिए सक्रिय पृथ्वी दबाव ($K_a$) और निष्क्रिय पृथ्वी दबाव ($K_p$) का अनुपात क्या है?

A) 1/3
B) 1/9
C) 9
D) 1

Correct Answer: B
Explanation: For φ=30°, K_a = (1-sin30)/(1+sin30) = 1/3.
K_p = 1/K_a = 3.
Ratio K_a / K_p = (1/3) / 3 = 1/9.

8. A soil having uniformity coefficient ($C_u$) less than 4 is called: 4 से कम एकरूपता गुणांक ($C_u$) वाली मिट्टी को क्या कहा जाता है?

A) Well graded soil
B) Uniformly graded soil
C) Gap graded soil
D) Highly plastic soil

Correct Answer: B
Explanation: For well-graded gravel, $C_u > 4$. For well-graded sand, $C_u > 6$. A $C_u$ near 1 indicates uniform grading (soil of same size).

9. Statement I: Vane shear test is suitable for stiff clays.
Statement II: Unconfined Compression Test is a special case of Triaxial Test where cell pressure is zero. कथन I: वेन कतरनी परीक्षण (Vane shear test) कठोर मिट्टी के लिए उपयुक्त है।
कथन II: अनकंफाइंड कम्प्रेशन टेस्ट ट्राइएक्सियल टेस्ट का एक विशेष मामला है जहाँ सेल प्रेशर शून्य होता है।

A) Only I is correct
B) Only II is correct
C) Both I and II are correct
D) Neither is correct

Correct Answer: B
Explanation: Statement I is False; Vane shear is for **soft, sensitive clays**. Statement II is True.

10. According to Terzaghi, the ultimate bearing capacity of a purely cohesive soil (c) for a strip footing is: टेरज़ागी के अनुसार, स्ट्रिप फुटिंग के लिए शुद्ध संसंजक मिट्टी (c) की अंतिम धारण क्षमता (ultimate bearing capacity) क्या है?

A) 5.7 c
B) 5.14 c
C) 1.3 c
D) 9 c

Correct Answer: A
Explanation: For purely cohesive soil (φ=0), $N_c = 5.7$, $N_q = 1$, $N_γ = 0$. For strip footing at surface: $q_u = cN_c = 5.7c$. (Note: Skempton uses 5.14).

11. In a flow net, the space between two adjacent flow lines and two adjacent equipotential lines is called: फ्लो नेट में, दो आसन्न फ्लो लाइनों और दो आसन्न इक्विपोटेंशियल लाइनों के बीच की जगह को क्या कहा जाता है?

A) Flow path
B) Flow field
C) Potential drop
D) Discharge tunnel

Correct Answer: B
Explanation: The elementary square/rectangle formed in a flow net is called a Flow Field.

12. Pycnometer method is used to determine: पिक्नोमीटर विधि का उपयोग क्या निर्धारित करने के लिए किया जाता है?

A) Water content and Specific Gravity
B) Particle size distribution
C) Bearing capacity
D) Liquid limit

Correct Answer: A
Explanation: Pycnometer is commonly used for coarse-grained soils to find both G and w.

13. On the ‘Dry side’ of the Optimum Moisture Content (OMC), the soil structure is generally: OMC के ‘शुष्क पक्ष’ (Dry side) पर, मिट्टी की संरचना आमतौर पर कैसी होती है?

A) Dispersed
B) Flocculated
C) Single grained
D) Honeycombed

Correct Answer: B
Explanation: Dry of OMC leads to flocculated structure (random orientation), while wet of OMC leads to dispersed structure (parallel orientation).

14. Assertion (A): Immediate settlement is calculated using elastic theory.
Reason (R): It occurs immediately after the application of load in both cohesionless and cohesive soils. कथन (A): तत्काल निपटान (Immediate settlement) की गणना इलास्टिक थ्योरी का उपयोग करके की जाती है।
कारण (R): यह लोड लगाने के तुरंत बाद बिना संसंजक और संसंजक दोनों प्रकार की मिट्टी में होता है।

A) Both A and R are true and R is correct explanation
B) Both A and R are true but R is NOT correct explanation
C) A is true but R is false
D) A is false but R is true

Correct Answer: A
Explanation: Immediate settlement is elastic in nature. Formula used: $S_i = qB(1-μ²)/E_s \cdot I_f$.

15. Negative skin friction on a pile occurs when: पाइल पर नकारात्मक त्वचा घर्षण (Negative skin friction) तब होता है जब:

A) Soil settles more than the pile
B) Pile settles more than the soil
C) Soil is very hard
D) Pile is made of steel

Correct Answer: A
Explanation: When the surrounding soft soil settles relative to the pile, it drags the pile downward, reducing its load-carrying capacity.

16. The shape of the phreatic line in an earth dam is: मिट्टी के बांध (earth dam) में फिएटिक लाइन का आकार कैसा होता है?

A) Circular
B) Parabolic
C) Straight line
D) Elliptical

Correct Answer: B
Explanation: Based on Casagrande’s solution, the top-most seepage line (Phreatic line) follows a base parabola.

17. In a triaxial test, if the cell pressure is 100 kPa and deviator stress at failure is 150 kPa, find the major principal stress. ट्राइएक्सियल टेस्ट में, यदि सेल प्रेशर 100 kPa है और फेल्योर पर डेविएटर स्ट्रेस 150 kPa है, तो प्रमुख मुख्य तनाव (major principal stress) ज्ञात करें।

A) 50 kPa
B) 150 kPa
C) 250 kPa
D) 100 kPa

Correct Answer: C
Explanation: σ₁ = σ₃ + σ_d.
σ₁ = 100 + 150 = 250 kPa.

18. Liquefaction of soil is most common in: मिट्टी का द्रवीकरण (Liquefaction) सबसे अधिक किसमें होता है?

A) Dense dry sand
B) Loose saturated sand
C) Hard clay
D) Well graded gravel

Correct Answer: B
Explanation: During dynamic loading (earthquakes), pore water pressure increases in loose saturated sands, making effective stress zero.

19. Match Sampler types with their disturbance levels:
1. Thin walled sampler | P. Highly disturbed sample
2. Split spoon sampler | Q. Undisturbed sample
3. Auger | R. Representative disturbed sample सैंपलर प्रकारों का उनके डिस्टर्बेंस स्तर के साथ मिलान करें:
1. पतली दीवार वाला सैंपलर | P. अत्यधिक डिस्टर्ब सैंपल
2. स्प्लिट स्पून सैंपलर | Q. अनडिस्टर्ब सैंपल
3. ऑगर (Auger) | R. प्रतिनिधि डिस्टर्ब सैंपल

A) 1-Q, 2-R, 3-P
B) 1-P, 2-Q, 3-R
C) 1-R, 2-P, 3-Q
D) 1-Q, 2-P, 3-R

Correct Answer: A
Explanation: Thin-walled samplers minimize area ratio to get undisturbed samples. Split spoon (used in SPT) gives disturbed samples.

20. Find the critical hydraulic gradient ($i_c$) for a soil with G = 2.65 and void ratio e = 0.65. G = 2.65 और रिक्ति अनुपात e = 0.65 वाली मिट्टी के लिए महत्वपूर्ण हाइड्रोलिक ढाल ($i_c$) ज्ञात करें।

A) 1.5
B) 0.5
C) 1.0
D) 2.0

Correct Answer: C
Explanation: i_c = (G-1) / (1+e).
i_c = (2.65 – 1) / (1 + 0.65) = 1.65 / 1.65 = 1.0.

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