CWT–04
Booklet No.:
Booklet Series:
03092014
Soil Mechanics
(Civil Engineering)
A
Student Name:
Roll Number:
Duration: 90 Minutes
PAPER
MAXIMUM MARKS: 60
INSTRUCTIONS
1.
IMMEDIATELY AFTER THE COMMENCEMENT OF THE EXAMINATION, YOU SHOULD CHECK THAT THIS TEST BOOKLET
DOES NOT HAVE ANY UNPRINTED OR TORN OR MISSING PAGES OR ITEMS ETC. IF SO, GET IT REPLACED BY A
COMPLETE TEST BOOKLET.
2.
This Test Booklet contains 30 questions. Each question comprises four responses (answers). You will select the
response which you want to mark on the Answer Sheet. In case you feel that there is more than one correct
response, mark the response which you consider the best. In any case, choose ONLY ONE response for each item.
3.
You have to mark all your response ONLY on the separate Answer Sheet provided.
4.
All items carry equal marks.
5.
Before you proceed to mark in the Answer Sheet the response to various items in the Test Booklet, you have to fill
in some particulars in the Answer Sheet as per instructions.
6.
Each questions 2 marks and 2/3 negative mark is assigned for the wrong answer.
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P h ( 0 1 1 ) - 2 6 1 9 4 8 6 9 , C e l l : 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7 : E - ma i l : q h e n g i n e e r z o n e @ g ma i l . c o m
Soil Mechanics
(1.)
A long a phreatic line in an earth dam
(a.) Total head is constant but not zero
(b.) Total head is everywhere zero
(c.) The pressure head is everywhere zero
(d.) None of the above
Ans: c
(2.)
Match the following lists:
List-I
A.
B.
C.
D.
List-II
1. Flexible footing on cohesive soil
2. Rigid footing on cohesive soil
3. Rigid footing on cohesion less soil
4. Flexible footing on cohesion less soil
2
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
Codes:
A
B
C
D
(a.)
3
2
4
1
(b.)
1
2
3
4
(c.)
2
1
4
3
(d.)
4
1
2
3
Ans: a
(3.)
Specific gravity of soil sample is 3.0. If the water content is 15% & degree of
saturation is 40%. What will be the dry density of the soil?
(a.) 2.5 g/cm3
(b.) 5.1 g/cm3
(c.) 3.9 g/cm3
(d.) 13.849 g/cm3
Ans: d
Exp: S.G.  3.0, W  15%, Sr  40%
d 

1 w

Sr 
Vw
W
, W  w  100
Vv
Ws
S.G.  3  G
e
WG 0.15  3.0

 1.125
Sr
0.4
G w
3  9.81
 G  Se 

 13.849
w 
1  e 1  1.125
 1 e 
d  
(4.)
A standard oedometer test in the laboratory indicated that a 0.02 m thick clay
specimen took 0.5 day to undergo 90% primary consolidation. How many days
will a 2m thick layer of identical clay sandwiched between sand layers & subject
to an identical stress increment take to undergo the serve
(a.) 5000 days
(b.) 2000 days
(c.) 3000 days
(d.) 6000 days
Ans: a
Exp: CV 
3
TV d 2
t
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(5.)

d12 d22

t1
t2

 0.012 12

 0.5 
t2

t2  5000 days
If a saturated soil sample is consolidated, the degree of saturation will
(a.) Reduce
(b.) Increase
(c.) Remains constant
(d.) Become zero
Ans: c
(6.)
Soil samples A & B have void ratios of 0.5 & 0.7 respectively. If 1.5 m3 of soil
sample A & 1.7 m3 of soil sample B are mixed to form sample changing a
volume of 3.2 m3. Which one of the following correctly represents the porosity of
sample?
(a.) 0.375
(b.) 0.60
(c.) 1.66
(d.) 2.66
Ans: a
Exp: n A

VV
eA
0.5
, nA 

 0.333
V
1  e A 1.5
V .VA  n A  VA  0.333  1.5  0.5
nB 
VV
eB
0.7


 0.412
V
1  eB 1.7
VVB  n B  VB
V  VB  0.412  1.7  0.7
n A B 
(7.)
VVA   VVB
V A  VB

0.5  0.7
 8.375
3.2
The Atterberg limits of a clay are 38%, 27% and 24.5%. It’s natural water
content is 30%. The clay is in which state:
(a.) Plastic
(b.) Solid
(c.) Semi-solid
(d.) Liquid
4
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
Ans: a
Exp: wL  wP  ws
wn lies here so plastic state.
(8.)
A cohesive soil sample was taken from an SPT & natured to the laboratory in a
glass jar. It was found to weight 0.141 kg. The sample was then placed in a
container of V = 500 cm3 & 423 cm3 of water were added to fill the container.
From these data, what was the unit weight of the soil in kN/m3.
(a.) 17.9
(b.) 18.9
(c.) 19.9
(d.) 20.9
Ans: a
Exp:  
m
0.141 kg
g

 1.831
3


v
500  423 cm
cm3
2

r   g  1.381
g
m  1 kN   102 cm   1 kg 
 9.81 2   3   
 
3
cm
s  10 N   1 m   103 g 
 17.692 kN/m3
(9.)
The type of soils formed below sea water are known as:
(a.) Lawstrine
(b.) Marine
(c.) Loes
(d.) Colluvial
Ans: b
(10.)
The limit of porosity ‘n’ lies in the following
(a.) 0  n  1
(b.) 0  n  1
(c.) 0  n  
(d.) 0  n  1
Ans: a
(11.)
For uniformly graded sand the maximum & minimum possible void ratio is
respectively
(a.) 0.61, 0.31
(b.) 0.71, 0.21
(c.) 0.91, 0.35
5
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(d.) 0.51, 0.11
Ans: c
(12.)
The soil sample coated with wax displaces a volume 300 cc when inserted in a
water filled vessel. The weight of soil is 200 g & weight of wax used for coating is
20 g. Also  wax  0.89 g/cc . The bulk density of soil '  ' in g/cc will be
(a.) 0.321
(b.) 0.621
(c.) 0.721
(d.) 0.421
Ans: c
Exp: V1  VW 
 300 
r 
(13.)
Wwax
rwax
20
 277.528 cc
0.89
W1
200

 0.721 g / cc
V1 277.528
The hydrometer corrections meniscus correction, temperature correction &
dispersing agent correction are respectively:
(a.) Always negative, always positive, always negative
(b.) Always positive, always negative, always positive
(c.) Always positive, can be negative, positive, or, always negative positive
(d.) Always negative, can be negative or positive, always positive,
Ans: c
(14.)
The graph between percentage finner & diameter is given below in arithmeticallog scale. The graph for well graded soil is given as:
(a.) A
6
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(b.) B
(c.) C
(d.) D
Ans: a
(15.)
A compacted cylindrical specimen 50 mm diameter & 100 mm long is to be
prepared from a dry soil. If the specimen is required to have a water content of
15% (% of air voids is 20). The weight of soil & water required in the preparation
of above soil sample is: (Given G = 2.69)
(a.) 2.953 kN, 0.443 gm
(b.) 1.953 gm, 0.463 gm
(c.) 3.953 kN, 0.562 kN
(d.) 4.953 kN, 0.362 kN
Ans: a
Exp: Total volume of sample



4

 D2  l
  50  101   10 cm3
2
4
V  196.35 cc
V  Va  Vwater  Vsolids  196.35 cc
% na 
Va
 100  20
V
 Va  0.2  196.35  39.27 cc
 Vw  Vs  196.35  39.27
 157.08 cc ….. (1)
Vw  Vs  196.35  39.27  57.08 cc
 %w
15 
Ww
 100
Ws
Vw  w
V
 w  15
Vs  s
VsG
Vw  0.15  GVs  0.15  2.69  Vs
Vw  0.4035  Vs
---- (2)
Using equation (1) & (2)
Vw  45.16 cc , Vs  111.9 cc
 Ws  Vs  G   w  111.9 cc  2.69  1
7
gm 9.81

 2.953 kN
cc 1000
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
Ww  Vw .rw 
(16.)
45.16
kgN
 9.8
 0.443 kN
1000
cc
In a drained triaxial compression test conducted on a dry sand, failure occurred
when the deviators stress was 218 kN/m2 at a confining pressure of 61 kN/m2.
What is the effective angle of shearing resistance & the inclination of failure
plane to major principal plane?
(a.) 34°, 62°
(b.) 34°, 25°
(c.) 40°, 25°
(d.) 40°, 65°
Ans: d

Exp: 1   3 tan3  4  

2


218  61  61tan2  45  
2

   40.242
40.242
 45  65.121
2

(17.)
The consistency of saturated cohesive soil is affected by
(a.) Water content
(b.) Particle size distribution
(c.) Density inside
(d.) Coefficient of permeability
Ans: a
(18.)
Honey comb structure is most common in soil size ranging from:
(a.) 0.2 to 0.02 mm
(b.) 0.02 to 0.0002 mm
(c.) 0.002 and 0.0002 mm
(d.) < 0.0002 mm
Ans: b
(19.)
If wall earth system is rigid then which of the following coefficient of earth
pressure will be close to real conditions
(a.)
8
1  sin 
1  sin 
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(b.)
(c.)
(d.)
1  sin 
1  sin 

1 

1 
Ans: c
(20.)
Correct the following statements
Statement-I: Coarser soils have greater void ratio & permeability.
Statement-II: Presence of montmorillsnite mineral causes swelling & shrinkage
properties in soils.
Of above statements:
(a.) Both I and II are true
(b.) II is true but I is false
(c.) I is true but II is false
(d.) Neither I nor II is true
Ans: b
(21.)
A retaining wall is to be provided in form of a cut off wall. If it is to be provided
at section A-A’ as shown in the figure. Which of the following will be the most
appropriate section of cutoff wall
(a.)
9
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(b.)
(c.)
(d.)
Ans: b
Exp: As moment is maximum at point C.
So maximum area is required at top.
(22.)
Find the greatest height to which a vertical cut that can be made without
support in a clay of density 200 kg/m3. The Mohr envelope per the tri-axial test
on the clay sample is shown below
10
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(a.) 2.6 m
(b.) 3.9 m
(c.) 7.8 m
(d.) 2.9 m
Ans: d
Exp: Critical depth of cut Zc 
 
Hc
r
1
KA
2000  9.81
 19.620 kN/m3
1000
KA 
1  sin 
1  sin 
sin  
5
 0.781
6.403
 KA 
 Zc 
1  0.781
 0.123
1  0.781
45
1

19.620
0.123

c    5 For pure class
= 2.907 m (cm)
(23.)
In the stability analysis of earthen slopes the Taylor’s stability charts are based
on the total stresses using the:
(a.) Method of slices
(b.) v  0 analysis
(c.) Friction circle method
(d.) None of these
Ans: a
11
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(24.)
According to Colomb’s theory, the rupture surface of soil mass retained by an
inclined wall as shown in the figure is
(a.) 2
(b.) 1
(c.) 10 m2
(d.) 3
Ans: a
(25.)
Assertion (A): Negative skin friction will act on piles in filled up soils, which
should be considered in design of pile foundations.
Reason (R): The filled up soils consolidates & develop a drag force on the pile in
opposite direction has of actual drag force.
(a.) Both A & R are true but R is the correct explanation of A
(b.) Both A & R are true but R is not the correct explanation of A
(c.) A is true but R is false
(d.) A is false but R is true
Ans: a
(26.)
The most commonly used sampler for obtaining a disturbed sample of the soil is
(a.) Split spoon sampler
(b.) Open drive sampler
(c.) Piston sampler
(d.) Thin wall shell by tube sampler
Ans: a
(27.)
A pipe of 5 m diameter & of length 10 m is embedded in a deposit of clay. The
undrained strength parameters of clay are cohesion = 60 kN/m2 & the angle of
internal friction = 0. The spin friction capacity (kN) of the pile for an adhesion
factor of 0.6 is
12
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
(a.) 671
(b.) 565
(c.) 283
(d.) 106
Ans: b
(28.)
A plate load test was conducted in sand on a 300 mm diameter plate. If the
plate settlement was 5 mm at a pressure of 100 kPa, the settlement (in mm) of a
5m × 8m rectangular footing at the same pressure will be:
(a.) 9.4
(b.) 18.6
(c.) 12.7
(d.) 17.8
Ans: d
(29.)
Dilatancy correction is required when a strata is
(a.) Cohesive & saturated & also has N value of SPT > 15
(b.) Saturated silt / fine sand & N value of SPT < 10 after the overburden
correction
(c.) Saturated silt/fine sand & N value of SPT > 15 after the overburden
correction
(d.) Coarse sand under dry condition & N value of SPT < 10 after the overburden
correction
Ans: c
(30.)
The degree of disturbances of a sample collected by sampler is expressed by a
term called the area ratio. If outer diameter & inner diameter of sample are
D0 & Di respectively, the area ratio is:
(a.)
D02  Di2
Di2
(b.)
Di2  D02
Di2
D02  Di2
(c.)
D02
(d.)
13
Di2  D02
D02
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m
Soil Mechanics
Ans: a
(31.)
Cohesion in soil
(a.) Decreases active pressure & increase passive resistance
(b.) Decreases both active pressure & passive resistance
(c.) Increases the active pressure & decreases the passive resistance
(d.) Increases both active pressure & passive resistance
Ans: a
(32.)
For a clayey soil  = 25 kN/m3. The shear strength & bear capacity parameters
are as follows:
Test
Cohesion
Angle of (  )
Bearing capacity
C (kN/m2)
Shearing resistance
factors
Nc
Nq
N
CU
48
18°
13.1
4.6
2.9
UU
89
0°
5.7
1.0
0
CD
26
29°
28.9
15.8
11.2
The area is prone to earthquake. For a square footing of dimension 4m × 4m &
depth 2m net ultimate bearing capacity immediately after construction would
be:
(a.) 1692.4 kN/m2
(b.) 2163.2 kN/m2
(c.) 709.5 kN/m2
(d.) 1526.3 kN/m2
Ans: c
Exp: As immediate B.C. is required source UU results
QU  1.3 cNc   Df Nq  0.4 BNr
 1.3  89  5.7  25  2  1.0  0
 709.490 kN/m2
14
EN G IN EER S ZO N E, 6 5 / C , P r at ee k Ma r k et , Ne ar C an a ra B an k, Mu n i r ka, N ew Del h i -1 1 0 0 6 7 ,
P h (0 1 1 ) -2 6 1 9 4 8 6 9 , C e l l: 9 8 7 3 0 0 0 9 0 3 , 9 8 7 3 6 6 4 4 2 7: E - ma i l : q h en gi n e er zo n e @ g m ai l . co m