Geo Technical Engineering
Exam Duration: 45 Mins Total Questions : 30
A retaining wall retains a sand strata with \(\phi =30°\) upto its top.If a uniform surcharge of 12 t/m2 is subsequently put on the sand strata, then the increase in the lateral earth pressure intensity on the retaining wall will be
- (a)
1 t/m2
- (b)
2 t/m2
- (c)
4 t/m2
- (d)
8 t/m2
According to Terzaghi's theory, the ultimate bearing capacity at ground surface for a purely cohesive soil and for a smooth base of a strip footing is
(where. c = unit of cohesion of soil.)
- (a)
2.57c
- (b)
5.14 c
- (c)
5.7 c
- (d)
6.2 c
A dry soil sample has equal has equal amount of solids and voids by volume. Its void ratio and porosity will be
- (a)
Void Ratio Porosity (a) 1.0 100% - (b)
Void Ratio Porosity (b) 0.5 50% - (c)
Void Ratio Porosity (c) 0.5 100% - (d)
Void Ratio Porosity (d) 1.0 50%
Which on of the following represents the dry unit weights, of a soil sample which has a bulk unit weight of at a moisture content of w% ?
- (a)
\(\frac { w.\gamma t }{ 100 } \)
- (b)
\(\gamma\)t \(\left( 1+\frac { w }{ 100 } \right) \)
- (c)
\(\gamma\)t \(\left( \frac { 100 }{ 100+w } \right) \)
- (d)
\(\gamma\)t \(\left( \frac { 100-w }{ 100 } \right) \)
Two soil samples A and B have porosities nA = 40% and nB = 60% respectively. Ehat is the ratio of void ratio eA : eB ?
- (a)
2 : 3
- (b)
3 ; 2
- (c)
4 ; 9
- (d)
9 ; 4
Embankment fill is to be compacted at a density of 18 kN/m3. The soil of the borrow area is at a density of 15 kN/m3 . What is the estimated number of trips of 6 m3 capacity truck for hauling the truck required for compacting 100 m3 fill of the embankment?
- (a)
14
- (b)
18
- (c)
20
- (d)
23
A smooth rigid retaining wall 6 m high carries a uniform surcharge load of 123 kN/m2 .The backfill is clayey sand (\(\gamma \)= 16.0 kN/m3 , \(\phi =25°\) and c= 6.5 kN/m2). The total passive thrust on the wall per metre length will be
- (a)
100 kN/m
- (b)
287.19 kN/m
- (c)
711.57 kN/m
- (d)
1011.57 kN/m
For the retaining wall shown in figure below assume that the wall can yield sufficiently to develop active stage.Using Rankine's active earth pressure theory, the active force per metre of the wall will be (Take, \({ \gamma }_{ w }\)=9.81 kN/m3)
- (a)
55.55 kN/m
- (b)
79.5 kN/m
- (c)
127.5 kN/m
- (d)
116.35 kN/m
A soil has liquid limit of 60%, plastic limit of 35%and shrinkage limit of 20% and it has a natural moisture content of 50%. The liquidity index of the soil is
- (a)
1.5
- (b)
1.25
- (c)
0.6
- (d)
0.4
Generally, the bearing capacity of a pile group is
- (a)
equal to the sum of bearing capacities of individual piles in friction pile.
- (b)
equal to the sum of bearing capacities of individual piles in end bearing piles
- (c)
less than the sum of bearing capacities of individual piles in end bearing piles
- (d)
greater than the sum of bearing capacities of individual piles in friction piles.
Group symbols assigned to silty sand and clayey sand are respectively
- (a)
SS and CS
- (b)
SM and CS
- (c)
SM and SC
- (d)
MS and CS
When a retaining wall moves away from the backfill, the pressure exerted on the wall is termed as
- (a)
passive the earth pressure
- (b)
swelling pressure
- (c)
pore pressure
- (d)
active the earth pressure
A single pile, 50 em in diameter and 15 m long is driven in clay having an average unconfined compressive strength of 100 kPa. The ultimate bearing capacity of the pile, neglecting end bearing, if any and assuming shear mobilization factor of 0.8 around the pile is
- (a)
942 kN
- (b)
1884 kN
- (c)
1177.5 kN
- (d)
1334.5 kN
The standard plasticity chart of classify fine-grained soil is shown in the given figure. The area marked X represents
- (a)
silt of low plasticity
- (b)
clay of high plasticity
- (c)
organic soil of medium plastirity
- (d)
clay of Intermediate plasticity
A soil has liquid limit 32% and slope of A-line is 13.5. The group symbol of the soil as per IS classification
- (a)
Cl
- (b)
MI
- (c)
CL
- (d)
ML
The laboratory tests on a sample yielded the following results
Plasticity index 32%
Liquidity index 0-15
Activity number 1-58
Which of the following inferences can be drawn?
1 The soil is very stiff.
2 The soil is medium soft.
3. The soil is highly plastic
4. The soiI is medium plastic
5. The soil is active
Select the correct answer using codes given below
- (a)
1, 3 and 5
- (b)
1, 3 and 4
- (c)
2, 3 and 5
- (d)
1, 2 and 4
An embankment is to be constructed with a granular soil (Ybulk = 20 kN / m3) on a saturated clayey silt deposit (undrained shear strength = 25kPa). Assuming undrained general shear failure and bearing capacity factor of 5.7. The maximum height (in m) of the embankment at the failure is
- (a)
7.1
- (b)
5.0
- (c)
4.5
- (d)
2.5
A group of 16 piles of 10 m length and 0.5 m diameter is installed in a 10 m thick stiff clay layer underlain by rock. The pile-soil adhesion is 0.4, average shear strength of soil on the sides is fOO kPa, undrained shear strength of the soil at the base level is also 100 kPa.
(ii)Assuming 100% efficiency, the group side resistance is
- (a)
5026.5 kN
- (b)
10000 kN
- (c)
10053.1 kN
- (d)
20106.2 kN
A canal having side slopes 1:1 is proposed to be constructed in cohesive soil to a depth of 10 m below the ground surface. The soil properties are
\({ \phi }_{ u }=15°,{ C }_{ u }=12\quad kPa,e=1.0,G=2.65\)
If there is sudden draw down of water in the canal and if Taylor's stability number for the reduced value of \({ \varphi }_{ u }\) is 0.126, the factor of safety with respect to cohesion against the failure of bank will be
- (a)
1.85
- (b)
1.18
- (c)
0.84
- (d)
0.53
A granular soil possesses saturated density of 20 kN/ m3, Its effective angle of internal friction is 35°.If the desired factor of safety is 1.5. The safe angle of the slope for this soil, when seepage occurs at end parallel to the slope surface will be
- (a)
\(25°\)
- (b)
\(23°\)
- (c)
\(20°\)
- (d)
\(13°\)
The following data were obtained when a sample of medium sand was tested in a constant head permeter
Cross-section area od sample : 100 cm2
Hydraulic gradient 10
Discharge collected 10 cc/s.
The coefficient of permeability of the sand is
- (a)
0.1 m/s
- (b)
0.01 m/s
- (c)
1\(\times\)10-4 m/s
- (d)
1\(\times\)10-8 m/s
A well of diameter 20 cm fully penetrates a confined aquifer. After a long period of pumping at a rate of 2720 L/min. The observations of draw down taken at 10 m and 100 m distances from the centre of the well are found to be 3 m and 0.5 m respectively. The transmissivity of the aquiferis
- (a)
676 m2 / day
- (b)
576 m2 / day
- (c)
526 m2 / day
- (d)
249 m2 / day
The following data were obtained from a liquid limit test conducted on a soil sample.
Number of blows | 17 | 22 | 25 | 28 | 34 |
---|---|---|---|---|---|
Water content(%) | 63.8 | 63.1 | 61.9 | 60.9 | 60.5 |
The liquid limit of the soil is
- (a)
63.1%
- (b)
62.8%
- (c)
61.9%
- (d)
60.6%
In a pumping out test, the draw down is 5 m, if the coefficient of the permeability of the soil is 10-4 m/s the radius of influence will be about
- (a)
250 m
- (b)
300 m
- (c)
150 m
- (d)
200 m
An excavation is proposed for a site consisting of homogenous, isotopic layer of silty clay, 10 m thick above a deep deposit of sand. The ground water is 1 m below ground level. Given, e = 0.60 and G = 2.70. The limiting depth of excavation to avoid heaving will be (see figure)
- (a)
4.85 m
- (b)
5.15 m
- (c)
6.15 m
- (d)
7.85 m
At a reclamation site for which the soil strata is shown in figure, a 3 m thick layer of a fill material is to be laid instantaneously on the top surface. If the coefficient of volume compressibility mv for clay is 2.2 x 104 m2 / kN. The consolidation settlement of the clay layer due to placing of fill material will be
- (a)
69.3 mm
- (b)
139 mm
- (c)
228 mm
- (d)
278 mm
A soft normally consolidated clay layer is 20 m thick with a moisture content of 45%. The clay has a saturated unit weight of 20' kN/m3, a particle specific gravity of 2.7 and a liquid limit of 60%. A foundation load will be subjected at the centre of the layer to a vertical stress increase of 10 kPa. Groundwater level is at the surface of clay. (Take, \({ \gamma }_{ w }\) = 10 kN/m3).
1. The consolidation settlement of the foundation.
- (a)
71 mm
- (b)
87.6 mm
- (c)
175 mm
- (d)
192 mm
Consolidation in soils
- (a)
is a function of the effective stress
- (b)
does not depend on the present stress
- (c)
is a function of the pore water pressure
- (d)
is a function of the total stress
For a certain loading condition, a saturated clay layer undergoes 40% consolidation in a period of 178 days. What would be the additional time required for further 20% consolidation to occur?
- (a)
89 days
- (b)
222.5 days
- (c)
329.5 days
- (d)
400.5 days
A cylindrical specimen of soil has an unconfined compressive strength of 120 kN/m2. In a tri-axial compression test a specimen-of the same soil when subjected to a chamber pressure of 40 kN/m2 failed at an additional stress of 160 kN/m2. The shear strength parameters of the soil will be (\(\phi \), c) respectively
- (a)
\({ 19 }^{ \circ }\), 39 kN/m2
- (b)
\({ 19 }^{ \circ }\), 43 kN/m2
- (c)
\({ 29 }^{ \circ }\), 43 kN/m2
- (d)
\({ 0}^{ \circ }\), 43 kN/m2