Civil Engineering (CE) : Mock Test 6 For GATE


65 Questions MCQ Test Mock Test Series for Civil Engineering (CE) GATE 2020 | Civil Engineering (CE) : Mock Test 6 For GATE


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This mock test of Civil Engineering (CE) : Mock Test 6 For GATE for GATE helps you for every GATE entrance exam. This contains 65 Multiple Choice Questions for GATE Civil Engineering (CE) : Mock Test 6 For GATE (mcq) to study with solutions a complete question bank. The solved questions answers in this Civil Engineering (CE) : Mock Test 6 For GATE quiz give you a good mix of easy questions and tough questions. GATE students definitely take this Civil Engineering (CE) : Mock Test 6 For GATE exercise for a better result in the exam. You can find other Civil Engineering (CE) : Mock Test 6 For GATE extra questions, long questions & short questions for GATE on EduRev as well by searching above.
QUESTION: 1

Identify the correct spelling of the word.

Solution:

The correct spelling of the word is 'definitive' which means '(of a conclusion or agreement) done or reached decisively and with authority.' Thus option 2 is the correct answer.

QUESTION: 2

This is the place that _______

Solution:

The preposition 'about' is mandatory here thus option 1 and 4 are eliminated. Option 2 is correct as the tense present perfect continuous fits here. It conveys the meaning that the person usually talked about the place. 

QUESTION: 3

She is brave. Her brother is more brave.

Select the most suitable sentence with respect to grammar and usage.

Solution:

Options 1 and 2 are incorrect as they change the meaning of what is mentioned. Option 3 is incorrect as with 'less' we use the adjective in positive form and not comparative form. The correct word here should be 'brave.' Option 4 is thus the correct answer.

*Answer can only contain numeric values
QUESTION: 4

When a four digit number is divided by 65, it leaves a remainder of 29. If the same number is divided by 13, the remainder would be______


Solution:

Let number is N

N = 65 k +29

Now 

∴ Remainder = 3

QUESTION: 5

Complete the following sentence.

I was ___ ___  for the bus and then I ___ sight of Craig passing by.

Solution:

The word 'here' and 'there' both can be used here but should be followed with 'waiting' as no other word can fit here. The word 'caught' is correct here as 'catch a sight' means 'to see something.' Option 2 thus has the correct combination of words. The word 'cot' means 'a small bed with high barred sides for a baby or very young child.'

*Answer can only contain numeric values
QUESTION: 6

4 – digit number greater than 5000 are randomly formed from the digits 0, 2, 3, 5 and 7. The probability of forming a number divisible by 5 when the digits are repeated is ______


Solution:

For a number to be greater than 5000, d1 should be filled with either 5 or 7

∴ Total numbers formed when the digits are repeated = 2 × 5 × 5 × 5 = 250

total cases = 250 -1 = 249 ( case of 5000 is not included)

Now, For the number to be divisible by 5, unit digit d4 should be either 0 or 5.

∴ Total no. of ways = 2 × 5 × 5 × 2 = 100

favorable cases = 100 - 1=9 ( 5000 is not included))

∴Required Probability = =0.397

QUESTION: 7

It is theoretically possible that bacteria developed on Venus early in its history and that some were carried to Earth by a meteorite. However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets. So, even if bacteria did arrive on Earth from Venus, they must have died out. 

The argument is most vulnerable to which of the following criticisms?

Solution:

The question asks which of the statements given in the options can weaken the argument put by the author that all bacteria from Venus must have died out.

The passage states that since there is a single strain of bacteria which exists on the Earth, they all must be belonging to the Earth or let's say a single planet. But here the author does not take into consideration (as can be argued from his theory) the fact that may be all the bacteria came from Venus and there are none which originally belong to the Earth. So this criticism as mentioned in option 3 makes the argument of the author vulnerable. 

Options 1, 2 and 4 are completely irrelevant criticisms as they do not address the main argument. The argument claims that if there were Venusian bacteria on Earth, then they must have died out by now. Whether there are bacteria originally from Earth that have also disappeared from Earth is irrelevant to the question and has no effect on the given argument.

QUESTION: 8

A man sells three articles A, B, C and gains 10% on A, 20% on B and loses 10% on C. He breaks even when combined selling prices of A and C are considered, whereas he gains 5% when combined selling prices of B and C are considered. What is his net loss or gain on the sale of all the articles?

Solution:

Let a, b and c be the cost prices of the three articles A, B and C.

SP = CP + Profit (or) SP = CP – Loss

⇒ SP of A = 1.1a; SP of B = 1.2b; SP of C = 0.9c

By question,

1.1a + 0.9c = a + c ⇒ 0.1a = 0.1c ⇒ a = c

1.2b + 0.9c = 1.05(b + c) ⇒ 0.15b = 0.15c ⇒ b = c = a

Gain% = {(SP – CP)/CP} × 100

⇒ Net gain on the sale of all the articles =   =

∴ Net gain on the sale of all the articles = 6.66%

QUESTION: 9

Which of the following inferences can be drawn from the above graph?

Solution:

Option 1 is false as graph says there is decrease in students qualifying in Physics in 2015 compared to 2014.

Option 2

Let no. of students qualifying in Biology in 2013 be 100

⇒ No. of students qualifying in Biology in 2014 = 100 – 10% of 100 = 90

⇒ No. of students qualifying in Biology in 2015 = 90 + 10% of 100 = 99

∴ The number of students qualifying in Biology in 2015 is less than that in 2013

Option 3 and option 4 are incorrect since no detail is given regarding how many students qualified the subject in 2013.

QUESTION: 10

DRQP is a small square of side a in the corner of a big square ABCD of side A. What is the ratio of the area of the quadrilateral PBRQ to that of the square ABCD, given A/a = 3?

Solution:

Area of triangle PAB = Area of triangle RCB (By symmetry)

∴ Area of Δ PAB = ½ × PA × AB

= ½ × 2A/3 × A = A2/3

Area of ΔRCB = A2/3

Now, Area of ABCD = Area of DRQP + Area of PAB + Area of RCB + Area of PBRQ

A2 = a2 + A2/3 + A2/3 + Area of PBRQ

As, A/a = 3 ⇒ a = A/3

⇒ Area of PBRQ = 

*Answer can only contain numeric values
QUESTION: 11

If the Laplace transform of y(t) is given by Y(s) = L(y(t)) =   then y(0) + y'(0) = _____.


Solution:

Y(s) = L(y(t)) =

Apply inverse Laplace transform,

⇒ y(t) = 
Differentiate with respect to ‘t’.

⇒ y(0) + y'(0) = 1

*Answer can only contain numeric values
QUESTION: 12

The value of  will be _____


Solution:





= 1

QUESTION: 13

Consider the following statements P and Q:

(P):If  M =    then M is singular.

(Q): Let S be a diagonalizable matrix. If T is a matrix such that S + 5 T = I, then T is diagonalizable.

Which of the above statements hold TRUE?

Solution:

A matrix is said to be singular, if determinant of that matrix is zero.

= 1 (18 – 12) - 1 (9 – 4) + 1 (3 – 2)

= 6 – 5 + 1 = 2 ≠ 0

M is non singular

(Q) A matrix can be diagonalizable when it has distinct eigen values

S is a diagonalizable matrix. Hence, has distinct eigen values.

Let S be a 3 × 3 matrix and the eigen values of s are λ1, λ2, λ3

Given that, S + 5T = I

From the properties of Eigen values,

(a) If λ1 is an eigen value of matrix A, then -λ1 ­will be on eigen value of matrix -A.

(b) If λ1 is an eigen value of matrix A, then (λ1 + 1) will be an eigen value of matrix (A + I)

(c) If λ is an eigen value of matrix A, then  will be an eigen value of matrix  where K is a scalar.

From the above properties, eigen values of T are,

As λ1, λ2, λ3 are distinct values, λ′1,λ′2,λ′3 will be distinct.

Hence, matrix T is diagonalizable

So, only Q is true.

QUESTION: 14

 = 0 .If x = 0 at t = 0 and x = 1 at t = 1, the value of x at t = 2 is

Solution:

A.E is, (D2 – 3D + 2) = 0

⇒ (D – 1) (D – 2) = 0

⇒ D = 1, 2

x(t) = C1et + C2e2t

x = 0 at t = 0

⇒ 0 = C1 + C2 ⇒ C1 – C2

x = 1 at t = 1

⇒ 1 = C1e1 + C2e2

⇒ 1 = C1e1 + (-C1) e2

⇒ C1(e1 – e2) = 1

x(2) = C1e2 + C2e4

   

= e + e2

*Answer can only contain numeric values
QUESTION: 15

 

If for two vectors  and , sum   is perpendicular to the difference  The ratio of their magnitude is


Solution:



QUESTION: 16

Consider plane truss below and identify the correct option.

Solution:

Static indeterminacy of the Planer structure:

DS = R – r

R → no. of unknowns = 3

r → no. of equilibrium equations = 3

D= 3 – 3 = 0

As all the three Reactions (1, 2, 3) are non-parallel, non-concurrent and non-trival, So structure is externally stable.

For Internal stability of truss:

m ≥ 2J -3

m → no. of member

J → no. of Joints

m = 6

J = 5

6 ≥ 2 × 5 – 3

6 ≥ 10 – 3 = 7

As no. of members is less than (2J – 3), therefore the truss is internally unstable.

QUESTION: 17

Which of the following given statement is not correct?

Solution:

Factor affecting concrete strength

a) concrete porosity

b) water/cement ratio

c) Soundness of aggregate

d) Aggregate paste bond

e) Cement related parameters.

Hence, The water cement ratio (w/c) is not only factor influencing the strength of concrete.

At water/cement ratio more than 0.6, the increase in volume of hydrated product will not be able to occupy the space already filled with water. Hence, porosity increase and strength decreases.

The addition of the surfactant in the concrete mix results in the decrease in the cement ratio.

QUESTION: 18

The permissible limit for chlorides in water used for mixing concrete for reinforced concrete work as per IS 456 : 2000 is

Solution:

As per clause 5.4 of IS 456 : 2000

Potable water is considered satisfactory for mixing Concrete and the permissible limits for solids is shown in table below:

QUESTION: 19

The ratio of shear modulus to bulk modulus of the material for poisson ratio of 0.21 will be

Solution:

Concept:

Using the relation,

E = 3k(1 – 2μ)       ……(i)

E = 2G(1 + μ)         ……(ii)

From equation (i) and (ii)

3k(1 – 2μ) = 2G (1 + μ)

where k = Bulk modulus of the material

G = shear modulus of the material

μ = poisson’s ratio

Calculation:

μ = 0.21

3k(1 – 2μ) = 2G (1 + μ)

QUESTION: 20

A partially saturated soil sample is taken from a borrow pit and tested for its specific gravity, which is found to be 2.64. If the air content and water content of this sample is 20% and 26.5% respectively. Calculate the void ratio of the partially saturated soil sample when water content is 26.5% and change in the air content of the soil sample if the water content increased to 30%

Assume void ratio to be constant.

Solution:

Soil sample when water content is 26.5%:

Using the relation Se = wG

ac = 20%

ac + S = 100%

S = 100% - ac

S = 100% - 20%

S = 80%

w = 26.5%

0.80 × e = 0.265 × 2.65

e = 0.878

e = 87.8% (ans)

Soil sample when water content is 30%:

wI = 30%

G = 2.65

e = 0.878

SI e = Wi G

SI × 0.878 = × 2.65

SI = 0.905

SI = 90.5%

ac1+S= 100%

ac1 = (100 − 90.5)%

ac1+S= 100%

ac1 = (100 − 90.5)%

change in the air content = ac − acI

Δac = (20 – 9.5)%

Δac = 10.5% (Ans)

*Answer can only contain numeric values
QUESTION: 21

A plate load test was conducted in clay on a 450 mm diameter plate and the settlement of the plate is recorded as 10mm. if the settlement of foundation is not to exceed 35 mm, the width of the foundation required will be _____mm.


Solution:

Concept:

Using the relation

Where

Sf = settlement of foundation

Sp = settlement of plate

Bf = width of footing/foundation

Bp = width of plate

Calculation:

Sf = 35 mm

Sp = 10 mm

Bp = 450 mm

Bf = 1575 mm

Therefore width of foundation required will be 1575 mm.

QUESTION: 22

Following results are obtained after the sieve analysis of the soil sample:

(i) % of particles passing through 0.075 mm IS sieve = 4%

(ii) % of particles having size greater than 0.075 mm retained over 4.75 mm IS sieve = 62%

(iii) Coefficient of uniformity = 5

(iv) Coefficient of curvature = 1.5

As per ISSC system, the soil is classified as:

Solution:

From the test results:

(i) % of particles retained over 0.075mm IS sieve = (100 – 4)% = 96%

So, soil is coarse Grained soil

(ii) % fineness = 4% < 5%

(iii) As 62% (more than 50%) coarse fraction is retained over 4.75 mm IS sieve, the soil is termed as Gravel

Also, Cu = 5 > 4

Cc = 1.5 which lies between 1 and 3

So, soil is termed as well graded Gravel

Hence, soil is GW

QUESTION: 23

Which among the following clay mineral has least base exchange capacity?

Solution:

Base Exchange Capacity: The ability of the clay particles to absorb ions on its surface or edges is called Base or cation exchange capacity. Base exchange capacity depends upon the size of particles and and mineral structure.

QUESTION: 24

The given network diagram shows the detailed necessary for the CPM network analysis:

All the numerical values are given in days. The free float for the activity (3) – (5) will be

Solution:

Free float (FF) = Total float (FT) – Head event slack (Sj)

Total float is the maximum available time in excess to activity completion time.

FF for the activity [(3) – (5)] = FT [(3) – (5)] – S(5)

= (14 – 8) – 4 – 2

= 0 days

*Answer can only contain numeric values
QUESTION: 25

A rectangular channel of 3m width carrying a discharge of 6m3/sec. If the specific Energy at depth (y1) is 20% more than specific Energy at critical depth, Then the depth of flow (y1) will be ________ m.

Take acceleration due to gravity to be 9.81 m/s2


Solution:

Concept:

Critical depth of flow:

q = discharge per unit width

Calculation:



Specific Energy at critical depth =
= 1.1122m

Specific Energy at depth “y1” = 1.20 Ec

E1 = 1.20 × 1.1122

E1 = 1.3347m

y1 = 1.191m

QUESTION: 26

As per IS 10500: 2012, the permissible limits in absence of alternate source of water for calcium and magnesium in the drinking water respectively will be (in ppm)

Solution:

As per IS 10500: 2012,

As per IS 1055: 2012, the permissible limits in absence of alternate source of water for calcium and magnesium in the drinking water respectively will be 200 ppm and 100 ppm.

*Answer can only contain numeric values
QUESTION: 27

A confined coastal aquifer has an effective depth of 25 m. During the experiment to check the salt concentration in the water with discharge 0.5 m3/s, the head difference in the two observation well was 0.5 m, located at 271.8 m and 100 m distance form the center of the test well. The hydraulic conductivity of the aquifer (in mm/s) will be _______.


Solution:

Discharge form well in confined aquifer (Q)

where, k = hydraulic conductivity

d = depth of the aquifer

S1 = drawdown in the observation well 1

S2 = drawdown in the observation well 2

(S1 - S2) = 0.5m given

r1 = distance of observation well 1 form test well

r2 = distance of observation well 2 from test well.


⇒ k = 0.00637 m/s = 6.37 mm/s

QUESTION: 28

As per IRC: 31-102, the Vehicle Damage Factor (VDF) is a multiplier to convert the number of commercial vehicles of different axle loads and axle configuration into the number of repetitions of standard axle load of magnitude.

Solution:

The Vehicle Damage Factor (VDF) is a multiplier to convert the number of commercial vehicles of different axle loads and axle configuration into the number of repetitions of standard axle load of magnitude 80 kN.

It may also define as equivalent number of axles per commercial vehicles. The VDF varies with the vehicle axle configuration and axle loading.

QUESTION: 29

The speed and the theoretical maximum capacity of a single lane highway are 5m/s and 900 vehicle per hour respectively. The space headway and time headway respectively are:

Solution:

Theoretical maximum capacity of single lane can be expressed as

where, S = Capacity of single lane in vehicle per hour.

V = Speed in kmph

S = Space headway

Theoretical capacity can also be written as

Where, Ht = time headway

Calculation:

Space Headway (S) =

Time Headway (Ht) = 3600/900 sec

= 4 sec 

QUESTION: 30

Rapid curing bitumen are the bitumen cutback with commonly used distillate will be

Solution:

Cutback bitumen is a bitumen with less viscosity which, is achieved by addition of volatile diluent. Hence, to increase fluidity of the bitumen binder at low temperature the binder is blended with a volatile solvent.

The viscosity of the cut book and the rate of which hardness on the road depends on the characteristics and quantity of both bitumen and volatile oil used as diluent.

Cutback bitumen are available in there types:

1) Rapid curing → Naptha, gasoline

2) Medium curing → Kerosene or high diesel oil

3) Slow Curing → High boiling point gas oil. 

QUESTION: 31

In Accordance with IS 1343: 1980, In the absence of data, the approximate value of shrinkage strain for design of post-tensioning concrete member if age of concrete at transfer is 3 days will be?

Solution:

According to 1343: 1980, clause 5.2.4.1,

The approximate value of shrinkage strain for design shall be assumed as follows:

(i) For Pre-tensioning = 0.0003

(ii) ForPost − tensioning =

For t = age of concrete at transfer (days)

At t = 3 days

Shrinkage strain will be:

*Answer can only contain numeric values
QUESTION: 32

A cantilever beam of rectangular cross-section having 20 m span is subjected to uniformly distributed load throughout. The minimum effective depth required as per IS 456: 2000, so that the beam will not fail in deflection will be _______m. (up to two decimal places)

Use Modification factor for tension and compression reinforcement to be 0.95 and 1.345 respectively. 


Solution:

As per IS 456: 2000, clause 23.2.1

For cantilever beam:

For span ≤ 10m

For, span > 10m, the limit of deflection criteria is modified.

Where MF1 = Modification factor for tension = 0.95

MF2 = Modification factor for compression = 1.345

d ≥ 4.47m 

QUESTION: 33

Which one of the following statements is not correct?

Solution:

In bolted connection, the minimum width of lacing bars shall be three times the nominal diameter of the end bolt.

For more detail refers (IS 800:2007 section 7.6.2, page)

*Answer can only contain numeric values
QUESTION: 34

The total volume of water applied in 100 hectares of land was 25 × 107 liters. If the water stored in the root zone is 0.20 cm, then the field application efficiency will be_______%


Solution:

Total volume of water applied

= (25 × 107) × 10-3 m3

= 25 × 104 m3

Depth of the applied water

= 0.25 m

= 25 m

Also, Depth of water stored in the root zone = 20 cm

Therefore, field application efficiency


= 80%

*Answer can only contain numeric values
QUESTION: 35

The coefficient of variation of the rainfall for 10 rain gauges stations in a catchment was found to be 15%. If the admissible error allowed in the estimation of the mean rainfall data is 6% then, the optimum number of rain gauge station will be________.


Solution:

Optimum Number of Rain gauge station (N)

where, CV = Coefficient of variation

ϵ = admissible error

N = (2.5)2

N = 6.25 @ 7

Hence, Optimum Number of Rain gauge station will be 7.

QUESTION: 36

Consider the matrix equation

The condition for existence of a non-trivial solution, and the corresponding normalised solution (up to a sign) is

Solution:

For non-trivial solution, the rank of the matrix should be less than the number of variables. i.e. r < n.

For this, |A| = 0

⇒ (4c – 3b) – (2c – 6) + (b – 4) = 0

⇒ 4c – 3b – 2c + 6 + b – 4 = 0

⇒ 2c – 2b + 2 = 0

⇒ b = c + 1

The vectors x1, x2 ….. xare said to be linearly dependent, if there exist numbers λ1, λ2 ……. λn, not all zero such that

λ1x1 + λ2x2 + ….. + λnxn = 0

Here,

λ1 + λ2 + λ= 0      ----(1)

λ1 + 2λ2 + 3λ= 0      ----(2)

1 + bλ2 + 2cλ= 0

1 + (c + 1) λ2 + 2cλ= 0      ----(3)

From (1) & (3):

λ2 = -2λ3

λ1 = λ3 = λ

λ2 = -2λ

so corresponding normalised solution:


*Answer can only contain numeric values
QUESTION: 37

Two points are chosen randomly on a line 9 cm long. Determine the probability that the distance between them is less than 3 cm


Solution:

x: The distance of first point from the start of the line

y: distance of second point from the start of the line segment

x,y ϵ[0,9]

So sample space is Area of region bounded by

 x ≥ 0, y ≥ 0, x ≤ 9, y ≤ 9

This is square of side 9

Area = 81 cm2

The region of our interest is

|x-y| < 3

0 ≤ x ≤ 9

0 ≤ y ≤ 9

Area of shaded region = 2 (area of triangle) + area of rectangle

 = 45

Probability = 45/81 =0.55

QUESTION: 38

The area bounded by the curve y =x (3 – x)2, the x-axis and the ordinates of the maximum and minimum points of the curve is

Solution:

y = x(3 – x)2

=−x.2(3−x)+(3−x)= 3(x2−4x+3) = 0

(x - 3) (x – 1) = 0 ⇒ x = 3, x = 1



= 4sq.unit 

QUESTION: 39

Given N > 0, the iterative equation for finding  using Newton-Raphson method is:

Solution:


QUESTION: 40

If y = 3e2x + e-2x - αx is the solution of the initial value problem   = 1. Where, α, β ϵ R, then

Solution:

y = 3e2x + e-2x – αx

 

Given that, 

⇒ 1 = 6 – 2 - α

⇒ α = 3

Complementary solution

(D2 + β) = 0      ----(1)

The given is, y = 3e2x + e-2x – αx

It indicates, 2 and -2 are the roots of auxiliary equations.

⇒ (D + 2) (D – 2) = 0

⇒ D2 – 4 = 0

By comparing this equation with equation (1)

β = -4

QUESTION: 41

A 5 kg object with a speed of 20 m/s strikes a steel plate at an angle of 40° and rebound at the same speed at angle, change in linear momentum of the object will be

Solution:

Initial momentum (Pi) = Mobject × Vt

= 5 × 20

= 100 kg m/s

Final momentum (Pf) = Mobject × Vfinal

= 5 × 20

= 100 kg. m/s

Change of momentum in x-direction

= (Pf)x – (Pi)x = 100 cos 40° - 100 cos 40°

= 0

Change of momentum in y – direction

 = (Pf)y – (Pi)y

= 100 sin 40° - (-100 sin 40°)

= 2 × 100 × sin 40°

= 2 × 100 × 0.643

= 128.6 kg. m/s

QUESTION: 42

Two angle section ISA 100 × 100 × 10 are connected to either side of 14 mm gusset plate and is subjected to a working pull of 400 kN. If the welding is done in the workshop then, the length of the weld land l2 as shown in figure respectively will be?

(Take Ultimate strength as 410 MPa)

Solution:

Maximum size of the weld =  × thickness of angle with rounded toe.

= × 10 = 7.5mm

Hence, provided weld size (w) = 7.5 mm

Length of weld = l1 + l2 = L (say)

∴ Design the strength of the weld


= 994.2 L

Also, Force in each angle section will be =


(Because of two angle section)

∴ 300 × 10 = 994.2 × L

⇒ L = 301.75 mm

∴ L = l1 + l2

To provide zero eccentricity

Also, l× 28.4 = l× (100−28.4)

⇒ l1 = 216.053 mm = 216 mm

l2 = 302 – 216

l2 = 86

Hence l1 = 216 mm and l2 = 86 mm

*Answer can only contain numeric values
QUESTION: 43

A reinforced Concrete column of size 450mm × 550mm (overall depth) is provided with area of steel in compression as 4 bars of 25mm diameter. If the effective length of the column is 3.5m, the ultimate load carrying capacity of the column will be _______kN.

Use M-20 concrete and Fe-415 steel.


Solution:

Follow step by step method:

(i) check for short or long column

λ = 7.77 < 12

it is a short column

(ii) check for Minimum eccentricity

Minimum eccentricity (ex-x) is greater of

(ii) 20 mm

So, ex-x = 25.33 mm

ex-x < 0.05 × 550

25.33 < 27.5 mm

(O.K)

For ey−y = 22mm

ey-y < 0.05 × 450

22 mm < 22.5 mm

(O.K)

So, Load carrying capacity of the column will be

Pu = 0.4 fck Ac + 0.67fy Asc

fck = 20 N/mm2

 = 1963.50mm2

fy = 415 N/mm2

Pu = 0.4 × 20 × [450 × 550 – 1963.50] + 0.67 × 415 × 1963.50

Pu = 2510.24 kN

*Answer can only contain numeric values
QUESTION: 44

A saturated clay layer 5m thick is overlain by sand layer 3m deep. Consider the water table to be present at a depth of 2m below the ground level or surface. If 2m deep sand layer of Bulk unit weight 20 kN/m3 is placed immediately over the surface, the increase in the effective stress at centre of the clay layer at the instant will be ______ kpa.

 

Given:

(i) γsat of clay = 19 kN/m3

(ii) γsat of sand = 20 kN/m3

(iii) ) γt of sand above water table = 18 kN/m3

(iv) γ = 10 kN/m3


Solution:

Case I: When there is no fill over the surface

Effective vertical stress at centre of clay layer:

 = 18 × 2+20 × 1+19 × 2.5 − 10 × 3.5

 = 68.5kN/m= 68.5kpa

Case: II when 2m thick sand is immediately placed over the surface

When 2m thick sand is immediately placed over the surface, all the stresses is taken up by pore water. Hence pore water pressure is increased by 2(γt)sand2(γt)sand

Increase in pore water pressure at centre of clay layer = 2 × 20 = 40 kN/m2

Δ u = 40 kpa

Also, simultaneous increase in total vertical stress at centre of clay layer = 2 × 20 = 40 kN/m2

Δ σ = 40 kN/m2

Effective stress at centre of clay layer:

 = 18 × 2 + 20×1 + 40 + 19×2.5 −10×3.5 −40

 = 68.5kpa

*Answer can only contain numeric values
QUESTION: 45

A sand layer of 15 m is overlain by 7.5 m clay layer which is further overlain by 10 m deep pond. A standpipe is inserted in the sand layer at the bottom of clay stratum and rise of Elevation 7.5 m is observed in the standpipe due to artesian pressure in the sand stratum. Calculate the quantity of flow into the pond in litres per day from the clay layer per meter square of the pond bed.

Take γsat for clay and sand layer to be 20 kN/m3 and 19 kN/m3 respectively and permeability of clay layer is 1.5 × 10–5 cm/sec.

Use γw =10 kN/m3


Solution:

Concept:

Using Darcy’s law

q = kiA

k → permeability of soil

i → hydraulic gradient

A → Area of Soil Sample

Calculation:

hydraulic gradient (i) is = 

h = head causing flow in the clay layer

Take C1 as datum

Total head at C1 = Datum head + Pressure head

= 0 + (7.5 + 10 + 7.5) = 25 m

Total head at C2 = Datum head + Pressure head

= 7.5 + 10

= 17.5 m

(T.H)C1 > (T.H)C2

Flow is occurring from C1 to C2 (upward)

Head causing the flow = (T.H)c1 − (T.H)c2 

= 25 – 17.5

HL = 7.5m

L = 7.5m

A = 1 m2

k = 1.5 × 10–5 cm/sec

k = 1.5 × 10–7 m/sec

q = 1.5 × 10–7 × 1 × 1

q = 1.5 × 10–7 × 60 × 60 × 24 × 1 × 1

q = 12. 96 × 10–3 m3/day

q = 12.96 litres/day

*Answer can only contain numeric values
QUESTION: 46

If a hydraulic jump occurring in a rectangular channel 2.5 m wide such that the depth after the jump is 2.45m. If the discharge in the rectangular channel is 10 m3/sec, then the ratio of energy loss (EL) in the jump to the pre-jump depth will be?


Solution:

Concept:

Using the relation,

y1 = Pre-jump depth

y2 = Post-jump depth

F1 = Froude number before jump

F2 = Froude number after jump

Energy loss is given by:

Calculation:

y2 = 2.45 m

F2 = 0.333

y1 = 0.458 m

 

EL = 1.761 m

*Answer can only contain numeric values
QUESTION: 47

Find the minimum sight distance in m to avoid head-on collision of two cars approaching at 80 kmph and 50 kmph.

Use reaction time for both the driver, t = 2.5 sec, co-efficient of longitudinal friction f = 0.4 and brake efficiency of 80% in either case?


Solution:

Given, V1 = 80 kmph

V2 = 50 kmph

f = 0.4

Brake efficiency, η = 80% = 0.80

SSD for slow speed car = 

SSD50 = 0.278×50×2.5 + 

= 65.50 m

SSD for high speed car,

SSD80 = 0.278×80×1.5 + 

= 134.34 m

∴ stopping sight distance to avoid head-on collision of the two approaching cars,

SSD = SSD50 + SSD80

= 65.50 + 134.34

= 199.84 m

*Answer can only contain numeric values
QUESTION: 48

An observer (P) is standing on the deck of a ship just sees the another observer (Q) whose eye is 12m above the sea level. If the height of eye of the observer ‘P’ is 8m above the seal level. Determine the distance between the two observers in kms.

Ignore the effect of Refraction.


Solution:

Let d1 is the distance of observer ‘P’ from the horizon

d1 = 10.097 kms

Let d2 is the distance of observer ‘Q’ from the horizon

h2 = 12m

d2 = 12.367 kms

Total distance between the two observers

= d1 + d2

= 10.097 + 12.367

= 22.464 kms

QUESTION: 49

A cantilever beam of length ‘L’ and flexural rigidity EI Carries uniformly distributed load of w kN/m throughout the span and maximum deflection occur is ‘δ’. If the same beam of length ‘2L’and flexural rigidity “0.5 EI” is made simply supported, then the maximum deflection is observed to be

Solution:

Maximum Deflection of Cantilever beam of length L and flexural rigidity EI carries UDL of w kN/m is:

Maximum deflection of simply supported beam of length 2L and flexural rigidity 0.5 EI carries U.D.L. of w kN/m is:

*Answer can only contain numeric values
QUESTION: 50

For the Beam shown below, the value of unknown Reaction ‘X’ will be_____kN.


Solution:

Using Moment distribution method:

Using principal of superposition:


 = 190.5kN − m

But moment at B must be zero, so applying a counter moment of 190.5 kN-m at B to make final moment at B equal to zero, Half of (-190.5 kN-m) is transferred to fixed end A.

So,final moment at A = 

 = 189.75kN − m(clockwise) = y

∑F= 0 

x + Z = 150 kN

∑M= 0 

x.10 – 50 × 5 – 100 × 2 + 189.75 = 0

10.x = 260.25

x = 26.025 kN

QUESTION: 51

Find the value of P for collapse of the beam shown in figure.

Solution:


Internal work = 3MP(θ)+3MP(θ)+3MP(ϕ)+MP.ϕ = 3MP(θ)+3MP(θ)+3MP(ϕ)+MP

= MP(6θ+4ϕ) = MP(6θ+4ϕ) 

= MP(12ϕ+4ϕ) = 16MPϕ = MP(12ϕ+4ϕ) = 16MPϕ 

External work = 

Internal work done = 3MP(θ)+MP(θ+θ)+MP(θ) = 3MP(θ)+MP(θ+θ)+MP(θ) = 6MPθ

External work done = 

Hence true collapse load is 9Mp/L.

*Answer can only contain numeric values
QUESTION: 52

A geometrically similar model is made to the scale ratio of 1:14 to study the characterstics of spillway. If the energy dissipated per second in prototype is 15000 N-m, what will be the Energy dissipated per sec in model ________ N – m.


Solution:

Concept: As it is the case of spillway, So Fraude model law is applicable

Pm = Power in model = ρQmgHm

Pp = Power in Prototype = ρQpgHp





Calculation:


Pm = 20.45 N – m per second

Hence power in model will be 20.45 N – m per second

*Answer can only contain numeric values
QUESTION: 53

An inverted U-tube differential manometer is connected to two pipes X and Y. Pipe X and Y is carrying the oil of specific gravity in the ratio  = 0.96. If the difference in pressure between two pipes (py – px) is 1900 N/m2, then the density of the fluid flowing in pipe is ________ kg/m3.

Take the fluid in the manometer is oil of specific gravity 0.85.


Solution:

Ratio of specific gravity is given as:

 = 0.96 

 = 0.96 

ρx = 0.96 ρy

Pressure in the left limb at A – A

= px – ρx.g.0.45

= px – 0.96 ρy.g.0.45

Pressure in the Right limb at A – A

= py – ρy.g.0.35 – ρm.g.[0.45 + 0.25 – 0.35]

= py – ρy.g.0.35 – 0.85 × 1000 × g [0.35]

Pressure in the left limb at A – A = Pressure in the right limb at A – A

px – 0.96ρy.g.0.45 = py – ρy.g.0.35 – 297.5g

px – py = 0.432gρy – 0.35gρy – 297.5g

–1900 = 0.082gρy – 297.5g

ρy = 1266.09 kg/m3

ρx = 1215.45 kg/m3.

*Answer can only contain numeric values
QUESTION: 54

A transmission tower of height 14m was erected to top of a building. A theodolite is used to measure vertical angle to top and bottom of the tower and were measured as 9° and 6° respectively. Calculate the Reduced level (metres) of the top of the transmission tower if the staff reading of 1.425m was taken from the same point on a Benchmark of R.L 102.5m. Neglect curvature and refraction correction.


Solution:

In ΔPRS

In ΔPQS

V = Dtan6°

Dtan9° – Dtan6° = 14

D(tan9° – tan6°) = 14

D = 262.76 m

V = 262.76 tan6°

V = 27.62 m

R.L of top of the tower = (R.L)B.M + Staff reading on BM + V + 14

R.L.Q = 102.5 + 1.425 + 27.62 + 14

R.L.Q = 145.545 m

QUESTION: 55

The number of photographs required to cover an area of 30 km × 25 km if the scale of an aerial photograph is 1 in 15000 is?

Longitudinal overlap = 58%

side overlap = 29%

Format of photograph taken = 24 cm × 24 cm

Solution:

Concept:          

No. of photograph in the direction of flight (N1)

No. of photographs perpendicular to the direction of flight (N2)

Where,

Pl = overlap in the direction of flight

Pw = overlap in the direction perpendicular to the direction of fligh

tl = length of photograph in the direction of flight

w = width of photograph normal to direction of flight

L1 = Length of ground to be covered

W1 = Width of ground to be covered

S = Scale of the photograph

Total number of photograph required: = N1 × N2

Calculation:

L1 = 30000 m

W1 = 25000 m

Pl = 58%

Ps = 29%

l = 24 cm


N1 = 20.84


N2 = 10.78

Total no. of Photographs = N1 × N2

N = 20.84 × 10.78

N = 224.65 ≅ 225

*Answer can only contain numeric values
QUESTION: 56

A pile is driven through 5 m of soft clay which is underlain by stiff clay. The average cohesion from 5 m to 15 m depth is 160 kN/m2 and the end bearing resistance is 190 kN/m2. Calculate the Factor of safety of the pile against the safe working load of 500 kN. Take adhesion factor between stiff clay and pile to be 0.5. The diameter of the pile is 0.6 m. Neglect the skin friction from loose clay.

Take Nc = 9.


Solution:

Ultimate bearing capacity of pile is given by:

Qup = Qeb + Qsf

Where,

Qeb = End bearing resistance of the pile = CNcAb

Qsf = Skin friction resistance of the pile =

Where,

Ab = base area of the pile

Asf = Surface area of the pile

Calculation:

As no side resistance from the loose clay layer, so skin friction resistance is considered for stiff layer only for the length of (15-5) =10 m.

Qup = 9×190× +0.5×160×π×0.6×10

 

Qup = 483.49+1507.96

Qup = 1991.45 kN


Which is greater than 2.5 (o.k).

*Answer can only contain numeric values
QUESTION: 57

A Pipeline “PQ” of diameter 500mm and length 300m carries water as shown in figure below. The flow is occurring from P to Q.

 

If the point Q is 20 metres above point P and the pressure at point ‘P’ is 20 N/cmmore than that of pressure at point Q. Then calculate the rate of flow (litres per second) through the pipe?

Take friction factor to be 0.034.


Solution:

Applying Bernoulli’s equation at P and Q and take Point ‘P’ as datum:

ZP = 0[P as datum]

ZP = 0[Pasdatum]

ZQ = 20m

V= V[FromContinuityequation]

PP=PQ+20×104


Q = 0.1198 m3/sec = 119.8 liters/sec

*Answer can only contain numeric values
QUESTION: 58

A 8 hour unit hydrograph of a catchment of area 220 km2 is a triangular in shape with base width of 50 hours. A direct runoff hydrograph (DRH) of this catchment, due to 3 cm of effective rainfall for 4 hours will have a peak flow rate of _______m3/s.


Solution:

Area of triangle OAB = Volume of runoff water

½ × QP × 50 × 60 × 60 = 220 × 106 m2 × 1 cm

⇒Q= 220×10× 

Qp = 24.44 m3/s

For the Direct Runoff Hydrograph.

QPDRH = 3 × 24.44 m3/s

QPDRH = 73.33 m3/s

*Answer can only contain numeric values
QUESTION: 59

A rectangular concrete beam of cross-section 150mm wide and 400mm deep is prestressed by a cable with cross-sectional area of 350 mm2. The effective span of the beam is 11m. The cable profile is parabolic with eccentricity of 75mm above the centroid of the cross-section at supports and 75mm below at midspan. If one end of the cable is tensioned, then percentage loss of prestress in the cable due to friction will be____?

Take wobble correction factor (k) and coefficient of friction (μ) between steel reinforcement and duct surface to be 0.15 per 100m and 0.55 respectively.


Solution:

Concept:

Loss of prestress due to friction is given by:

Loss = p0 (kx + μα)

Where,

p0 = initial prestress

k = wobble correction factor

x = distance from Jacking end

x =  (when Jacking from both ends)

x = L (when Jacking from one end)

μ = Coefficient of friction between steel reinforcement and duct surface

α = Net change in gradient between two points of considerations.

Equation of Cable:

h = e1 + e2

e1 = eccentricity at end

e2 = eccentricity at centre

For x = 0

Calculation:

e1 = 75 mm

e2 = 75 mm

h = e1 + e2 = 75 + 75 = 150 mm

 

 = 0.10909radian

When Cable is tensioned at one end, the maximum loss of prestress occur at other end

Hence, at x = L = 11m

Loss of prestress = p0 (kx + μα)

x = 11m

μ = 0.55

α = 0.10909 radian

Loss = p(0.0015 × 11 + 0.55 × 0.10909)

Loss = p0 (0.07649)

% loss = 7.65%

*Answer can only contain numeric values
QUESTION: 60

A PSC beam (simple supported over effective span of 9m) of size 300 × 500mm is prestressed by 700 mm2 area of cable stressed to 1350 mpa. If the straight cable is provided with eccentricity of 150mm above the Neutral axis, then the stress developed at top fibres at centre of the beam will be ________ mpa

The beam is subjected to 25 kN/m of load (inclusive of dead weight)


Solution:

Final stress diagram

B.M. at centre =

w = 25 kN/m

L = 9m



P = Prestressing force = As × p

P = 700 × 1350

P = 945 × 103 N

Final stress developed at centre of beam at top fibres =


ft = 6.3 + 11.34 + 20.25

ft = 37.89 mpa

*Answer can only contain numeric values
QUESTION: 61

The theoretical volume of methane gas (in m3/tonnes of waste) that would be expected from the anaerobic digestion of a tonne of waste having the composition C50H100O40N will be ______.

Assuming, 1 mole of C50H10O40N will produce 27.125 mole of methane (CH4) and density of methane is 0.7167kg/m3.


Solution:

Molecular mass of C50 H100 O40 N

= (12 × 50) + (1 × 100) + (16 × 40) + (14 × 1)

= 1354 gm

 Molecular mass of CH4 = (1 × 12) + (4 × 1)

= 16 gm

∴ 1 mole of C50H100O40N will produce 27.125 mole of methane

∴ 1354 gm of C50H100O40N will produce 27.125 × 16 gm of methane

∴ Mass of methane = 

= 320.5 kg/tonne

Volume of methane gas =


= 447.2 m3/tonne of waste

*Answer can only contain numeric values
QUESTION: 62

The activated sludge process schematic flow diagram is shown in figure below: 

where, Q, Qw = flow rate, m3/d

θc = sludge age, days

X, Xr = microorganism- concentration (mixed – liquor volatile suspended solids or MLVSS)

The volume of sludge that must be wasted each day if wastage is accomplished from point A will be ______m3/day.


Solution:

According to definition

sludge age




Qw XR = 1000 kg/day

  

Qw = 100 m3/day

*Answer can only contain numeric values
QUESTION: 63

A filter baghouse is to process 15 m3/s of waste gas. The baghouse is to be divided into eight section of equal cloth area so that one section can be shut down for cleaning and/or repair while the others continue operating. Laboratory analysis indicate an air to-cloth ratio of 9.0 m3/min/m2.cloth will provided sufficient treatment. The bags are 0.25 m in diameter and 7.0 m long. The number of bags for the above physical arrangement to meet the requirement will be _________.


Solution:

Flow of air = 15 m3/s

Air to cloth ratio = 9 m3/min/m2 cloth.

∴Area of colth rqurired = 

= 100 m2.

Also, Area of each bag = π DH

= 3.14 × 0.25 × 7

= 5.5 m2

∴Number of bag requried = 

= 18.19

Since baghouse is to be divided into eight equal section of equal cloth area so that one section can be shut down for cleaning or repair.

∴ Minimum number of bags required

= 3 × 8 = 24

*Answer can only contain numeric values
QUESTION: 64

In a Laboratory analysis to evaluate strength of the flexible pavement through Marshall method of mix design, the specific gravity of fine aggregate and bitumen was not measured accidently. The coarse aggregate, fine aggregate, finer and bitumen are mixed in the relative proportion (% by weight) of 50, 40, 6 and 4 respectively. The specific gravity of coarse aggregate and finer are 2.72 and 2.6 respectively. If the theoretical specific gravity of the mix and the effective specific gravity of the aggregate in the mix are respectively 2.525 and 2.7 then, the specific gravity of bitumen is______


Solution:

The effective specific gravity of aggregates (Ge)


⇒ GFA = 2.675

Where GFA = specific gravity of fine aggregate.

Also Theoretical specific gravity

Where Gb = specific gravity of bitumen

⇒ Gb = 1.0099

⇒ Gb = 1.01

QUESTION: 65

A clayey soil sample in a consolidometer test showed decrease in void ratio from 1.15 to 1.05 when the pressure was increased from 0.30 kgf/cm2 to 0.60 kgf/cm2. If the same soil shows 10% more decrease in void ratio when the pressure was increased from 0.30 kgf/cm2 to 0.80 kgf/cm2, then change in coefficient of consolidation observed during the test will be?

Take initial coefficient of consolidation observed from test when the pressure was increased from 0.30 kgf/cm2 to 0.60 kgf/cm2 to be 12 m2/year.

Solution:

Coefficient of compressibility (av)=

Δe = change in void ratio

increase in effective stress

 

Coefficient of volume compressibity 

e0 = initial void ratio

Also,

k = cvmvγw

k = permeability of soil Sample

cv = coefficient of consolidation

m= coefficient of volume compressibility

Calculation:

Δe1 = 1.15 – 1.05

Δe1 = 0.10

Δσ1 = 0.60 – 0.30

Δσ1 = 0.30 kgf/cm2




= 3.80×10−3cm2/sec 

k = 3.80 × 10–3 × 0.155 × γw

Now,

Δe2 = 1.10 × 0.10 = 0.11

Δσ2 = 0.80 – 0.30

Δσ2 = 0.50

As permeability of both the sample is Sames,

So,

3.80×10−3×0.155=cv2×0.122 

cv2=4.83×10−3cm2/sec 

cv2=15.22m2/ year

Change in coefficient of consolidation:

Δcv=cv2−cv1 

Δcv = 15.22 – 12

Δcv = 3.22 m2/year