Download Visvesvaraya Technological University (VTU) BE ( Bachelor of Engineering) Civil Engineering 17 Scheme 2020 January Previous Question Paper 4th Sem Basic Geotechnicai Engineering
Module-2
3 a. List and explain various soil structures.
b. What is the effect of compaction on soil properties?
c. Following are the results of a standard proctor compaction test on a soil:
Water content, % 8.5 12.2 13.75 15.5 18.20
Weight of wet soil in kgs 1.8 1.94 2.0 2.04 2.03
(06 Marks)
(06 Marks)
Plot the compaction curve and get maximum dry density and OMC. Also plot ZAV line.
Important Note
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Fourth Semester B.E. Degree Examination, Dec. RAJA' 020
Basic Geotechnicai Engineering
Time: 3 hrs. Max. Marks: 100
Note: Answer any FIVE full questions, choosing ONE full question from each module.
Module-1
1 a. With the help of 3-phase diagram define: void ratio, porosity, water content and degree of
saturation. (08 Marks)
b. Derive from first principles, the following phase relation:
=
? n
a
)G.y?,
d
1 WG
(06 Marks)
7
c. With the help of particle size distribution curve explain: well graded soil, uniformly graded
soil and gap graded soil. (06 Marks)
? -?
OR
2 a. With a neat sketch, explain the salient features of a plasticity chart. (08 Marks)
b. The natural dry density of a soil deposit was found to be I 7.5kN/m
3
. A sample of soil was
brought to the laboratory and the minimum and maximum dry densities were found as
16kN/rn
3
and 1901/mi respectively. Calculate the density index for the soil deposit.
o (06 Marks)
c. How many cubic meters of soil can be formed with a void ratio of 0.5 from 100 cubic meters
of soil having void ratio of 0.7. (06 Marks)
0
8
1
?
7-
M Cci
1
6
-
CO
E
E
(08 Marks)
v:
F.5
Q
rt
4
7-
c
Module-3
O a-2
5 a. Derive an expression to obtain coefficient of permeability under falling head condition.
(06 Marks)
r-4
b. Explain with a neat sketch the method of locating the phreatic line in a homogeneous earth
darn with horizontal filter. (06 Marks)
c.
Calculate the coefficient of permeability of a soil sample, 6 ems in height and 50cm
2
in
cross-sectional area, if a quantity of water equal to 430m1 passed down in 10 minutes, under
an effective constant head of 40cms. On oven drying the test specimen has a mass of
498 gins. Taking the specific gravity of soil solids as 2.65, calculate the seepage velocity of
water during the test.
(08 Marks)
1 oft
Take G = 2.75 and volume of mould as 995 c.c.
OR
4 a. Describe the three principal clay minerals. (08 Marks)
b. Explain electrical diffuse double layer and adsorbed water. (06 Marks)
c. What are the factors which affect compaction? (06 Marks)
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Module-2
3 a. List and explain various soil structures.
b. What is the effect of compaction on soil properties?
c. Following are the results of a standard proctor compaction test on a soil:
Water content, % 8.5 12.2 13.75 15.5 18.20
Weight of wet soil in kgs 1.8 1.94 2.0 2.04 2.03
(06 Marks)
(06 Marks)
Plot the compaction curve and get maximum dry density and OMC. Also plot ZAV line.
Important Note
?
-r- c
LI P HI
K
A
o
R
*
D
\IN:4 \
::,
Fourth Semester B.E. Degree Examination, Dec. RAJA' 020
Basic Geotechnicai Engineering
Time: 3 hrs. Max. Marks: 100
Note: Answer any FIVE full questions, choosing ONE full question from each module.
Module-1
1 a. With the help of 3-phase diagram define: void ratio, porosity, water content and degree of
saturation. (08 Marks)
b. Derive from first principles, the following phase relation:
=
? n
a
)G.y?,
d
1 WG
(06 Marks)
7
c. With the help of particle size distribution curve explain: well graded soil, uniformly graded
soil and gap graded soil. (06 Marks)
? -?
OR
2 a. With a neat sketch, explain the salient features of a plasticity chart. (08 Marks)
b. The natural dry density of a soil deposit was found to be I 7.5kN/m
3
. A sample of soil was
brought to the laboratory and the minimum and maximum dry densities were found as
16kN/rn
3
and 1901/mi respectively. Calculate the density index for the soil deposit.
o (06 Marks)
c. How many cubic meters of soil can be formed with a void ratio of 0.5 from 100 cubic meters
of soil having void ratio of 0.7. (06 Marks)
0
8
1
?
7-
M Cci
1
6
-
CO
E
E
(08 Marks)
v:
F.5
Q
rt
4
7-
c
Module-3
O a-2
5 a. Derive an expression to obtain coefficient of permeability under falling head condition.
(06 Marks)
r-4
b. Explain with a neat sketch the method of locating the phreatic line in a homogeneous earth
darn with horizontal filter. (06 Marks)
c.
Calculate the coefficient of permeability of a soil sample, 6 ems in height and 50cm
2
in
cross-sectional area, if a quantity of water equal to 430m1 passed down in 10 minutes, under
an effective constant head of 40cms. On oven drying the test specimen has a mass of
498 gins. Taking the specific gravity of soil solids as 2.65, calculate the seepage velocity of
water during the test.
(08 Marks)
1 oft
Take G = 2.75 and volume of mould as 995 c.c.
OR
4 a. Describe the three principal clay minerals. (08 Marks)
b. Explain electrical diffuse double layer and adsorbed water. (06 Marks)
c. What are the factors which affect compaction? (06 Marks)
OR
6 a. State the characteristics and uses of flownets. (08 Man
b. Explain the terms superficial velocity and seepage velocity. Derive the relationship betwee,
them. (06 Marks)
c. If during a Variable head permeability test on a soil sample, equal time intervals are noted
for drops of head from h
[
to h
2
and again from h2 to h
3
. Find the relationship between h
1
,
and h
3
. (06 Marks)
Module-4
7 a. Explain mass-spring analogy of consolidation of soils. (06 Marks)
b. Explain Casagrande's method of determination of pre consolidation pressure. (06 Marks)
c. The time to reach 40% consolidation of a two way drained saturated clay sample of 10mm
thick in the laboratory is 40 secs. Determine the time required for 60% consolidation of the
same soil 12m thick on an impervious layer subjected to same loading conditions. (08 Marks)
OR
8 a. Explain square root of time fitting method for determination of coefficient of consolidation.
(06 Marks)
b. Explain under consolidated, normally consolidated and over consolidated soils. (06 Marks
c. A layer of clay..8m thick underlies a proposed new building. The existing overburden
pressure at the centre of clay layer is 290kN1 m
2
and the load due to new building increases
the pressure
.
by 100kN/m
2
. Cc = 0.45, W = 50%, G = 2.71. Estimate consolidation
settlement.
(08 Marks)
Module-5
9 a. Explain Mohr-Coulomb theory of shear strength. (06 Marks)
b. Explain the advantages and disadvantages of direct shear test over triaxial shear test.
(06 Marks)
c. An unconfined compression test was conducted on an undisturbed sample of clay. The
sample had a diameter of 38mm and was 80mm long. The load at failure measured as 30N
and the axial deformation of the sample of failure was 12mm. Determine the unconfined
compressive strength and undrained shear strength of clay. (08 Marks)
OR
10 a. Explain sensitivity and thixotropy.
b. Explain vane shear test with a neat sketch.
c. The triaxial tests carried'Out on soil samples gave the following results:
Confining pressure,,,kNim
2
50 100 150
Deviator stress, kN/m
2
76 132 186
Pore water pressure , kNim
2
35 59 83
(06 Marks),
(06 Marks)
Plot Mohr's circle and obtain effective shear parameters. (08 Marks)
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This post was last modified on 02 March 2020