Category: Foundation Engineering

Foundation Engineering – MCQ || CivilNotePpt

Foundation Engineering – MCQ

1. Which of the following is not the objective of a foundation?

a) To increase the stability of the structure.
b) To increase the possibility of sliding of the structure.
c) To increase the stability against overturning.
d) All of these.

View Answer

b) To increase the possibility of sliding of the structure.

2. A foundation is to be called shallow when

a) Depth > width
b) Depth < Width
c) Depth ≤ Width
d) Depth ≥ Width

View Answer

c) Depth ≤ Width.

A foundation is to be called shallow when depth ≤ width.

3. Which of the following methods is the most advanced method for soil exploration

a) Test pits
b) Probing
c) Auger boring
d) Geophysical method

View Answer

d) Geophysical method.

4. In case of a wash boring method, a casing tube is driven into the ground with the help of a _____

View Answer

Water Jet.

In case of a wash boring method, a casing tube is driven into the ground with the help of a water jet.

5. Which of the following statement is correct?

a) The super-structure transmits the load of sub-structure to the underground soil.
b) The sub-structure transmits the load of super-structure to the underground soil.
c) Superstructure directly transmits all loads to the underground soil.
d)None of these.

View Answer

b) The sub-structure transmits the load of super-structure to the underground soil.

6. In case of a wash boring method, the driven casing pipe diameter is around __

a) 1 cm to 5 cm
b) 10 cm to 15 cm
c) 20 cm to 25 cm
d) 30 cm to 35 cm

View Answer

b) 10 cm to 15 cm.

7. If the water table is lying near or above the bearing surface of the soil, then the allowable bearing capacity of sandy soils and for gravel should be reduced by

a) 25 %
b) 50 %
c) 75 %
d) 90 %

View Answer

b) 50 %

8. Which types of piles are generally used for protecting structures from ships and floating objects?

View Answer

Fender piles.

9. What type of foundation is used when the soil near the ground surface is weak?

View Answer

Raft or Mat Foundation.

Relationship Between the SPT values with Angle of shearing resistance, Compactness and Relative Density

Relationship Between the SPT values with Angle of shearing resistance, Compactness, and Relative Density

The relationship between the standard penetration test(SPT or N) values with angle of shearing resistance(ɸ), compactness, and relative density are as follows:

SPT Values (N)	Compactness	Relative Density	Angle of shearing resistance(ɸ)
0 – 4	Very loose	0 – 15	<28°
4 – 10	Loose	15 – 35	28° – 30°
10 – 30	Medium	35 – 65	30° – 36°
30 – 50	Dense	65 – 85	36° – 41°
>50	Very Dense	>85	> 41°

1. The SPT-N value is the number of blows required to drive the sampler through the last

a) 15 cm
b) 30 cm ✅
c) 45 cm
d) 50 cm

2. The type of sampler used in standard penetration test is

a) Shelby tube sampler
b) Piston Sampler
c) Split Spoon Sampler ✅
d) Any of these

3. The first 15 cm of drive is considered

a) Blows for SPT
b) Blows for SPT-N
c) Blows for seating drive ✅
d) None of these

4. The hammer falling height is considered as

a) 75 cm ✅
b) 80 cm
c) 85 cm
d) 90 cm

5. The no.of blows for SPT will be

a) For the first 150 mm penetration
b) For the next 300 mm penetration ✅
c) Addition of (a) and (b)
d) None of these

6. After correction standard penetration value is equal to

a) 10 + 0.5(N-15)
b) 15 + 0.5(N-15) ✅
c) 20 + 0.5(N-15)
d) 30 + 0.5(N-15)

7. N value for loos sand is

a) 4
b) 8
c)10 ✅
d) 12

8. N value for very loos sand is

a) 2
b) 4 ✅
c) 8
d) 10

9. Chunk sampling is the process of

a) Disturbed sampling
b) Undisturbed sampling ✅
c) Both (a) and (b)
d) Water sampling

10. A good quality undisturbed soil sample is one which is obtained using a sampling tube having an area of

a) 24 %
b) 16 %
c) 12 %
d) 8 % ✅

11. Undisturbed soil samples are best collected by

a) Thin walled samplers ✅
b) Thick walled samplers
c) Direct excavation
d) Auger

12. The dilatancy correction in SPT is given by

a) N’ = 15 + (N-15)
b) N’ = 15 + 0.5(N-15) ✅
c) N’ = 15 + 0.5(N-10)
d) N’ = 15 + (N-10)

13. The degree of disturbance of soil sample is generally expressed by

a) Void ratio
b) Recovery ratio
c) Area ratio ✅
d) Consolidation ratio

14. The area ratio for a sampling tube with an inner diameter of 72 mm and outer diameter is

a) 0.85
b) 0.085
c) 8.5 ✅
d) 0.065

Read More:

3 Types of Soil Samples

Earth Pressure Theories

Swedish Circle Method For Analyzing The Slope Stability

Swedish Circle Method

Swedish circle method for analyzing the slope stability:

This method was first introduced by Fellenius (1926) for the analysis of slope stability of C-φ soil. In this method, the soil mass above the assumed slip circle is divided into a number of vertical slices of equal width. The forces between the slices are neglected and each slice is considered to be an independent column of soil of unit thickness. The location of the center of the failure arc (o) is assumed.

The weight of slice [latex] (w) = \gamma bh [/latex]
Where,

[latex] \gamma [/latex] = Bulk unit weight of soil;
h = Average height of slice &
b = Width of slice.

The weight of each slice (w) is plotted as a vector and it passes through the midpoint of each slice and is divided into normal & tangential components N & T respectively.

Then,

N=W cosα
T=W sinα

Considering the whole slip surface AB of length ‘L’. If ‘c’ is the unit cohesion, then the resisting force, from Coulomb’s equation is equal to (c L + N tanφ’):

Now,

Driving force = ΣT
Resisting force =c L + tanφ’ ΣN

Driving moment =(ΣT) × R
Resisting moment = c L R+ (tanφ’ ΣN × R).

ΣT = Sum of all tangential components.
ΣN = Sum of all normal components.

So, the Factor of safety (FOS) against sliding is

[latex] F =\frac{Resisting Moment}{Driving Moment}= \frac{c L + \tan \phi \sum N}{\sum T} [/latex]

Putting, N=W cosα, and T=W sinα

[latex] F = = \frac{c L + \tan \phi \sum W \cos \alpha }{\sum W \sin \alpha } [/latex]

Read More:

Types of Soil Samples

Assumption of Coulomb’s Theory

9 Assumptions of Coulomb’s Wedge Theory

Following are the 9 assumptions of Coulomb’s wedge theory or Coulomb’s wedge failure theory

1. The backfill is dry and cohesionless.

2. The backfill is also homogenous and isotropic.

3. The backfill surface is a plane surface and can be inclined.

4 The back of the wall is vertical and can be inclined.

5. The failure surface is a planner surface that passes through the heel of the wall.

6. The backfill is elastically non-deformable but may be breakable.

7. The position and the line of action of the earth’s pressure are known.

8. Friction is considered between the wall and backfill soil, Therefore, the contact surface is considered rough.

9. The sliding wedge is considered to be a rigid body and the earth pressure is obtained by considering the limiting equilibrium of the sliding wedge as a whole.

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Earth Pressure Theories – MCQ || Foundation Engineering ||

Earth Pressure Theories – MCQ

1. Depth of tensile zone near the surface of a cohesive fill is –

a) [latex] (c/\gamma )/ N\phi [/latex]

b) [latex] (\gamma/c )/ N\phi [/latex]

c) [latex] (2c/\gamma )/ N\phi [/latex] ✅

d) [latex] (2c/\gamma )/ (1/ N\phi) [/latex]

2. A verticle cut in clay soil with unit weight of 19 KN/m³ failed when the depth of cut was 4.8 m. What is the cohesive strength of clay?

a) 22 KN/m²

b) 20 KN/m²

c) 21 KN/m²

d) 23 KN/m² ✅

[Note: Formula, [latex] H_{c} = 4c/\gamma [/latex] Where, H = 4.8m, c = cohesive strength of clay, and [latex] \gamma [/latex] = 19 KN/m³ ]

3. Which Assumption is true for the Rankine Earth pressure Theory –

a) The soil mass is dry and cohesionless

b) The soil mass is semi-infinite and homogeneous

c) The back of the wall is verticle and smooth

d) All of These ✅

4. The lateral earth pressure coefficient K_p and K_a refers to

a) Total stree

b) Natural Stress

c) Effective Stress ✅

d) All of these

e) None of these

5. A verticle cut in soft clay be excavated without any lateral support up to a depth of

a) [latex] 2c/\gamma [/latex]

b) [latex] 2c\sqrt{N_{\phi }}/\gamma [/latex]

c) [latex] 4c\sqrt{N_{\phi }}/\gamma [/latex]

d) [latex] 4c/\gamma [/latex] ✅

6. Which condition fulfil the Coefficient of earth pressure at rest –

a) Greater than active earth pressure

b) Less than the Active earth pressure

c) Greater than the passive earth pressure

d) Less than the passive earth pressure

e) (a) but (d) ✅

f) (b) but (c)

7. According to Rankine’s theory the value of ‘c’ for cohesionless soil is

a) 1

b) 0 ✅

c) 1/2

d) Non of These

8. Which Assumption is true for Coulomb’s Wedge Theory

a) The backfill is dry, cohesionless, homogenous

b) The backfill is elastically undeformable

c) All of These ✅

d) None of These

Principle of Pavement Design – MCQ

Foundation on Slopping Ground

Differences Between Open Caissons and Pneumatic Caissons

Differences between well or open caissons and pneumatic caissons are as follows:

1. Structure

➤ Open caissons are box-type structures having their top and bottom open.

➤ Pneumatic caisson consists of an enclosure open at the bottom and closed at the top.

2. Cost

➤ Open caissons are relatively cheaper than pneumatic caissons.

➤ Pneumatic caissons are relatively costlier due to the use of compressed air in the working chamber.

3. Inspection

➤ Inspection and cleaning process at the bottom of the caisson can not be carried out in case of open caissons.

➤ But in the case of pneumatic caissons cleaning and testing process can be easily carried out, as the working chamber is dry.

4. If boulders are faced during construction

➤ The construction process will be slow and difficult if the boulder met during construction.

➤ No problem arises in the case of Pneumatic Caissons.

Read More:

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Use of Cofferdams

Installation Process of Ground Anchors

The entire procedure which is adopted for the installation of a ground anchor is described below in steps.

Step: 1

First of all, Holes of the required size are drilled with the help of a drill rig, etc., at the locations selected for the installation of anchors. The depth of the holes will be the desired depth as the design depth. Holes will be drilled with or without casing pipes, either vertically or at an inclination as required.

Step: 2

The anchor tendon is inserted centrally into the hole.

Step: 3

A grout, usually cement, is pumped into the space left between the tendon and the hole at predetermined grouting pressure. The pressures vary for the primary grouting and the secondary grouting.

Usually, a sheath is provided around the tendon in the secondary grout area to protect it from corrosion. If a casing pipe is used in drilling the hole, it will be withdrawn during grouting. The grout is finally allowed to cure.

Step: 4

A reaction and locking mechanism are connected on the ground surface or on a structural surface, which is called an anchor head.

Step: 5

Extended tensile stress is applied to the anchor by a hydraulic jack, which is greater than the design load. The value of this tensile stress usually varies from 1.25 to 2 times the design load of the anchor. They may sometimes be pre-stressed to control the longitudinal movement.

Step: 6

When the load is applied to the anchor, the lock-off system is engaged, and the applied tension from the jack is released.

Audio of Installation of Ground Anchors

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6 Purposes of Soil Exploration

Purposes of Soil Exploration

Soil exploration is a very important phase in the development of any structure. Although it costs a little more. But it’s favourable because it clears all doubts about the behaviour of the foundation.

Following are the 6 purposes of soil exploration or site investigation:

1. To determine the proper safe bearing capacity of the underlying soil.

2. To determine how deep the foundation should be taken.

3. To find out the depth of the underground water table and determine the ways to solve the problem due to groundwater if needed.

4. To select the safe and most profitable type of foundation.

5. Sit investigation or say soil exploration helps to overcome further any difficulties arise during construction work.

6. Make allowance for a possible settlement of the foundation.

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Types of Foundation Settlement

Depth Of Soil Exploration

Objects of Foundation

8 Objects of Foundation

Objects of Foundation

Foundation is provided for the following objects:

1. The foundation helps to distribute the loads(live load and dead load) that come from the superstructure, on a large area of subsoil, thus the intensity of the loads does not overcome the safe bearing capacity of the soil below the foundation.

2. Foundation increases the stability of the structures against sliding and overturning.

3. The foundation is provided to prevent the effects of structure from some disturbing forces like wind, rain.

4. To prevent lateral movement of the supporting material, in order that the safety of the structure isn’t at risk.

5. The foundation distributes the load uniformly to the underlying soil, therefore it prevents the unequal settlement of the foundation.

6. To provide a levelled and hard surface, in order to build superstructure over it.

7. It evenly distributes the pore water pressure.

8. To tighten the superstructure firmly with the soil.

Types of Foundation Settlement

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Foundation Engineering – MCQ || CivilNotePpt