# Bengal Engineering and Science University 2006 B.E Civil Engineering Soil Mechanics-II - Question Paper

the ques. paper is with the attachment in pdf format.

' B. E. (Civil) Part - III 6^{th} Semester Examination, May 2006

SOIL MECHANICS - II (CE-603)

Time: 3 hours___Full Marks: 100

FIRST HALF

Answer question no. ONE and any TWO from this half Write short notes on any FOUR from the followings:

(a) Stability number and safety factor

(b) Remedial measures for stabilizing slopes

(c) Objectives of compaction

(d) Factors affecting compaction

(e) Stabilization of soils with admixtures

(f) Types and functions of geotextiles

4@5 = 20

(a) Explain the suitability of different machineries for field compaction based on types of soils.

(b) In a standard Proctors compaction test, the following values were obtained. The volume of the mould is 940 x 10"^{6} m^{3} and the specific gravity of the soil solids is 2.60.

Wt. of wet sample (N) |
16.50 |
17.25 |
17.75 |
17.90 |
17.75 |

Water content (%) |
19.1 |
20.5 |
21.3 |
22.5 |
24.0 |

Plot the compaction curve, and determine (i) the maximum dry density, (ii) optimum moisture content and (iii) percentage of air voids at maximum dry density.

3. (a) Enumerate the methods used for field compaction control.

(b) What is degree of compaction?

(c) A core-cutter 125 mm high and 129 mm in diameter weighs 10.80 N when empty. It is used to determine the in situ density of a compacted soil in an embankment. The weight of the core - cutter full of compacted soil is 30.10 N. The water content of the soil is 12.2%. Determine the in situ dry unit weight and void ratio.

15

(a) Show that in case of infinite slopes in sand, the inclination of the inclined top surface with the horizontal is limited to the effective angle of internal friction of soil.

(b) An embankment 6 m high has a slope of 1V: 2H. The material of slope has (p = 30, c = 5 kN/m^{2} and y = 19 kN/m^{3}. A trial slip circle has a radius of 8.8 m and its center is at the same level as the top of the embankment. The slip circle passes through the toe. By the method of slices, find the factor of safety of the slope with respect to this slip circle.

15

5. (a) Enumerate the types of failure of slopes and causes of failure.

(b) Describe the Swedish circle method of analyzing the failure of finite slopes.

(c) Explain the method proposed by Fellenious to find out the centers of trial circles for stability analysis.

SECOND HALF

Sf*

Answer question no. and any TWO from this half

Write short notes on any FOUR from'the followings:

(a) Soil exploration planning

(b) Field vane shear test

(c) Merits and demerits of Rankines and Coulombs earth pressure theories

(d) Field applications of sheet pile walls

(e) Stabilization of bore hole

(f) Stability of retaining walls

4@5 = 20

(a) Explain standard penetration test.

(b) Enumerate the corrections applied to measured SPT values.

(c) The observed standard penetration test value in a deposit of fully submerged fine silty sand was 45 at a depth of 6.5 m from ground surface. The average saturated unit weight of the soil is 19.5 kN/m^{3} Determine the corrected SPT value and comment on the soil.

15

(a) Discuss any one of the soil exploration methods.

(b) Explain borehole log.

(c) Enumerate the contents of a soil report.

15

(a) Explain with example the different states of earth pressure.

(b) A retaining wall with smooth vertical back supports a two-layered sandy stratum to a depth of 6 m. The properties of the two layers are as follows:

Top layer c = 0; cp = 30'; \=M kN/m^{3}

Bottom layer c = 0; (p = 34; y ^{= }19 kN/m^{3}

The top layer is 4 m thick. Calculate the magnitude and resultant of active

lateral thrust on the wall. Use Rankines theory.

(c) A vertical cut in a clay soil with unit weight of 18.8 kN/m^{3} failed when the depth of cut was 4.6 m. What is the cohesive strength of the soil?

15

(a) What are the different types of cofferdams?

(b) Derive the expression for embedment depth of an anchored sheet pile having granular soil both at top and bottom of the dredge line.

(c) Determine the depth of embedment of a sheet pile wall to retain a backfill of 6 m high. The properties of the backfill material and the material below dredge line are as follows:

Backfill material Sand; c = 0; cp = 30'; y = 17 kN/m^{3}

Soil below dredge line : Clay; c = 35 kN/m^{1} ;cp = 0; y = IQ kN/m^{3}

15

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Attachment: |

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