Civil Engineering - Geotechnical Engineering
Exam Duration: 45 Mins Total Questions : 30
In a soil sample of weight 0.18 kg having a volume of 10-4 m3 and dry unit weight of 1600 kg/m3 is mixed with 0.02 kg of water than the water, content in the sample will be,
- (a)
30%
- (b)
25%
- (c)
20%
- (d)
15%
Which one of the following represents relative density of saturated sand deposit having moisture content of 25%, if maximum and minimum void ratio of sand are 0.95 and 0.45 respectively and specific gravity of sand particles is 2.6?
- (a)
40%
- (b)
50%
- (c)
60%
- (d)
70%
The following soils are compacted at the same compactive effort in the field.Which one of the following is the correct sequence in the increasing order of their maximum dry density?
- (a)
Silty clay-clay-sand-gravel sand-clay mixture
- (b)
Sand-gravel sand-clay mixture-silty clay-clay
- (c)
Clay-silty day-sand-gravel sand clay mixture
- (d)
Sand-gravel sand clay mixture-clay-silty-clay
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 geometrically identical footings X (Linear elastic) and Y (rigid) are loaded identically (shown along side). The soil reaction will
- (a)
be uniformly distributed for Y but not for X
- (b)
be uniformly distributed for X but not for Y
- (c)
be uniformly distributed for both X and Y
- (d)
not be uniformly distributed for both X and Y
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
For designing end bearing piles of square cross-section in clays having average unconfined compressive strength of 6 t/m2 , the net ultimate bearing capacity may be taken as
- (a)
15 t/m2
- (b)
18 t/m2
- (c)
20 t/m2
- (d)
27 t/m2
For a sample of dry, cohesionless soil with friction angle\(\phi \), the failure plane of the major principal plane by an angle equal to
- (a)
\(\phi \)
- (b)
\(45-\frac { \phi }{ 2 } \)
- (c)
45
- (d)
\(45+\frac { \phi }{ 2 } \)
What is the value of negative skin friction for a group of 4 piles of 30 cm diameter, 5 m long and spaced at 80 m c/c and having cohesive strength of soil as 25. kN/m2 ? Neglect point resistance.
- (a)
925 kN
- (b)
950 kN
- (c)
975 kN
- (d)
1000 kN
The relationship among specific yield (Sy), specific retention (Sr) and porosity of an aquifer is
- (a)
Sy=Sr+\(\eta \)
- (b)
Sy=Sr-\(\eta \)
- (c)
Sy=-Sr+\(\eta \)
- (d)
Sy=Sr+2\(\eta \)
A sand layer found at seafloor under 20 m water depth is characterized with relative density = 40%, emax= 1.0, e min = 0.5 and specific gravity of soil solids (Gs = 2.67). Assume the specific gravity of sea water to be 1.03 and unit weight of fresh water to be 9.81 kN/m3
What would be the change in the effective stress at 30 m depth into the sand layer, if the sea water level permanently rise by 2 m?
- (a)
19 kPa
- (b)
0
- (c)
21 kPa
- (d)
22 kPa
Consistency as applied to cohesive soils is an indicator of its;
- (a)
density
- (b)
moisture content
- (c)
shear strength
- (d)
porosity
Consider the following clay minerals
1. Kaolinite
2. Illite
3. Montmorillonite
Which one of the following is the correct sequence of the minerals given above in the increasing order of their grain size?
- (a)
3-2·1
- (b)
1-3-2
- (c)
1-2-3
- (d)
3-1-2
Examine the test arrangement and the soil properties given
(i) The maximum pressure that can be applied with a factor of safety of 3 through the concrete block, ensuring no bearing capacity failure in soil using Terzaghi's bearing capacity equation without considering the shape factor, depth factor and inclination factor is
- (a)
26.67 kPa
- (b)
60 kPa
- (c)
90 kPa
- (d)
120 kPa
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.
(i) The base resistance of a single pile is
- (a)
40 kN
- (b)
88.35 kN
- (c)
100 kN
- (d)
176.71 kN
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)
\(13°\)
Due to rise in temperature, the viscosity and unit weight of a percolating fluid are reduced to 70% and 90% respectively. Other things being constant, the change in coefficient of permeability will be
- (a)
20.0%
- (b)
28.6%
- (c)
63.0%
- (d)
77.8%
The observed value of the standard penetration number (N) at 10 m depth of a silty sand deposit is 13.The unit weight of the soil is 16 kN/m3. The N-value after correcting for the pressure of fines will be
- (a)
12
- (b)
13
- (c)
14
- (d)
15
The coefficient of permeability of a soil in horizontal and vertical directions are 3.46 and 1.5 m/day respectively. The base length of concrete dam resting on this soil is 100 m. When the flow net is developed for this soil with 1:25 scale factor in vertical direction the reduced base length of the dam will be
- (a)
2.63 m
- (b)
4.00 m
- (c)
6.08 m
- (d)
5.43 m
In a flow net diagram, the length of flow lines in the last square is 2 m, the total head loss is 18 m and the number of potential drops is 12. The value of exit gradient is
- (a)
0.33
- (b)
0.75
- (c)
1.33
- (d)
3.00
A saturated day stratum draining both top and bottom undergoes 50% in 16 yr under a applied load. If an additional drainage layer was present at the middle of clay stratum, 50% consolidation would occur in
- (a)
2 yr
- (b)
4 yr
- (c)
8 yr
- (d)
16 yr
A volume of 3.0\(\times \) 106 m3 of ground water was pumped out from an uncon fined acquifer having an area of 5 km2. The pumping lowered the water table from initial level of 102 m to 99 m. The specific yield of the aquifer is
- (a)
0.20
- (b)
0.30
- (c)
0.40
- (d)
0.50
The configuration of flow nets depend upon
- (a)
the permeability of the soil
- (b)
the difference between upstream and downstream heads
- (c)
the boundary conditions of flow
- (d)
the amount of seepage that takes place
A 3 m high retaining wall is supporting a saturated sand (saturated due to capillary action) of bulk density 18 kN/m3 and angle of shearing resistance 30°.The change in magnitude of active earth pressure at the base due to rise in ground water table from the base of the footing to the ground surface shall (take, \({ \gamma }_{ w }\) = 10 kN/m3)
- (a)
increase by 20 kN/m2
- (b)
decrease by 20 kN/m2
- (c)
increase by 30 kN/m2
- (d)
decrease by 30 kN/m2
The ultimate load capacity of a 10 m long concrete pile of square cross-section 500 mm \(\times \) 500 mm driven into homogenous clay I layer having undrained cohesion value of 40 kPa is 700 kN. If the cross-section of the pile is reduced to 250 m \(\times \) 250 mm and the length of the pile is increased to 20 m, the ultimate load capacity will be
- (a)
350 kN
- (b)
632.5 kN
- (c)
722.5 kN
- (d)
1400 kN
A normally consolidated clay layer settled by 20 mm when the effective stress was increased from 25 to 50 kN/m2. What will be its settlement when the effective stress is increased from 50 to 100 kN/m2?
- (a)
10 mm
- (b)
20 mm
- (c)
40 mm
- (d)
80 mm
A UU test is carried out on a saturated normally consolidated clay sample at a confining pressure of 3 kgf/ cm2. The deviator stress at failure is 1 kgf/ cm2, If another identical sample is tested at a confining pressure of 4 kgf/ cm2, What will be the vertical axial stress at failure?
- (a)
3 kqf/cm2
- (b)
4 kqf/cm2
- (c)
5 kqf/cm2
- (d)
Cannot be find
An undrained tri-axial compression test is carried out on a saturated clay sample under a cell pressure of 100 kN/m2. The sample failed at a deviator stress of 200 kN/m2. The cohesion of the given sample of clay is
- (a)
50 kN/m2
- (b)
100 kN/m2
- (c)
200 kN/m2
- (d)
300 kN/m2
A clay soil specimen when tested in unconfined condition gave an unconfined compressive strength of 100 kN/m2. A specimen of the same clay with the same initial condition is subjected to a UU tri-axial test under a cell pressure of 100 kN/m2. Axial stress (in kN/m2) at failure will be
- (a)
150
- (b)
200
- (c)
250
- (d)
300
Which one of the following soils has stress-strain response similar to that of dense sand? (OCR stands for Over Consolidation Ratio)
- (a)
Over consolidated clays having high OCR
- (b)
Over consolidated clays having low OCR
- (c)
Normally consolidated clays
- (d)
Unconsolidated clays