Soil Mechanics Questions and Answers – Soil as Three Phase System

This set of Soil Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Soil as Three Phase System”.

1. A soil mass in a three-phase system consists of ______
a) solids, water and air
b) sand, gravel and air
c) solids and water only
d) solids and air only
View Answer

Answer: a
Explanation: Solids and water, solids and air are two-phase systems. Sand, gravel and air are not the phases. Solids, water and air are considered to be a three-phase system of the soil mass.

2. When the soil is fully saturated, then there are no air voids present in it.
a) True
b) False
View Answer

Answer: a
Explanation: The air voids get filled with water leaving no air voids when the soil is fully saturated. When the soil is completely dry, then the soil will contain only air voids.

3. The volume of voids Vv is equal to the sum of ______
a) the volume of air and volume of solids
b) the volume of air and volume of water
c) the volume of water and volume of solids
d) the volume of water and the weight of water
View Answer

Answer: b
Explanation: The voids in soil mass are occupied by air and water. Hence, the volume of voids equals to the volume of air and volume of water.
advertisement
advertisement

4. The phase diagram is also known as _______
a) soil grain diagram
b) block diagram
c) constituents diagram
d) element diagram
View Answer

Answer: b
Explanation: It is always convenient to show the constituents occupying separate spaces as blocks. In the phase diagram, the soil occupies the bottom position. Water and air occupy the middle and top positions.

5. The weight of total voids is equal to the weight of Water.
a) True
b) False
View Answer

Answer: a
Explanation: The weight of total voids Wv is equal to the sum of weights of Water Ww and air Wa. Wv=Ww+Wa. Here, the weight of air is considered to be negligible. ∴ Wa=0
Therefore, Wv=Ww , i.e., weight of total voids is equal to the weight of Water.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. In the phase diagram, volumes are represented on the ________
a) left side
b) right side
c) top
d) bottom
View Answer

Answer: a
Explanation: Volumes are represented on the left side whereas weights are represented on the right side of the block diagram.
Volumes are on left side whereas weights are represented on right side of block diagram

7. The volume of solids is represented as _______ in the phase diagram.
a) Vv
b) VW
c) VS
d) Va
View Answer

Answer: c
Explanation: The volume of voids, water and air are represented as Vv, VW and Va. The volume of solids is represented as Vd or VS in the phase diagram.
advertisement

8. The weight of solids is represented as _______
a) Wd
b) WW
c) Wa
d) W
View Answer

Answer: a
Explanation: The weights of Water, air and total weight are represented as WW, Wa and W. The weight of solids is represented as Wd or WS in the phase diagram.

9. The total weight of the moist sample is the sum of _______
a) WW+Wd
b) Wa+WW
c) Wa+Wd
d) Wv
View Answer

Answer: a
Explanation: The sum of the weight of voids Wv and weight of solid is the total weight. The weight of total voids is equal to the weight of Water and weight of air. Since the weight of air is considered to be negligible, the weight of total voids is equal to the weight of Water. Therefore, the total weight of the moist sample is the sum of WW+Wd.
advertisement

10. For a fully saturated soil sample, the volume of voids is equal to _______
a) volume of air
b) volume of water
c) the volume of air and volume of water
d) the volume of water and volume of solids
View Answer

Answer: b
Explanation: In a fully saturated sample, the volume of voids gets completely filled by water leaving no air voids present in the sample. Hence, volume of voids equals the volume of water.

11. A soil sample weighs 190kN. After oven drying it weighs 150kN. What will be the weight of Water before oven drying?
a) 35 kN
b) 40 kN
c) 30 kN
d) 45 kN
View Answer

Answer: b
Explanation: Given,
Weight of soil sample W=190kN
Weight after oven drying Wd=150kN
Weight of Water WW=W-Wd
WW=190-150
WW=40kN.

12. In wet soil mass, air occupies one-seventh of its volume and Water occupies one- eighth of its volume. What will be the ratio of volume of voids with respect to the total volume?
a) 0.329
b) 0.279
c) 0.432
d) 0.286
View Answer

Answer: d
Explanation: Given,
Volume of Water Va= (1/7) total volume V
Volume of Water VW= (1/8) total volume V
Volume of voids Vv= Va + VW
Vv=(1/7)V+(1/8)V
Vv=(15/56)V=0.268V.

Sanfoundry Global Education & Learning Series – Soil Mechanics.

To practice all areas of Soil Mechanics, here is complete set of 1000+ Multiple Choice Questions and Answers.

advertisement
advertisement

Leave a Comment

Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & discussions at Telegram SanfoundryClasses.