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Reg No.:_ Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FOURTH SEMESTER B.TECH DEGREE EXAMINATION(R&S), MAY 2019

Course Code: CE208
Course Name: GEOTECHNICAL ENGINEERING I (CE)

Max. Marks: 100 Duration: 3 Hours
(Graph sheets - ordinary as well as semi-log - may be supplied on request)
PARTA

Answer any two full questions, each carries 15 marks Marks

1 a) Void ratio of a soil decreases from 1.15 to 0.85 upon densification. What is the 6

corresponding percentage decrease in volume?
b) A soil sample is compacted to a bulk unit weight of I18kN/m? at 10% water 9

content. Find the void ratio and degree of saturation of the soil. Also find the
weight of water to be added to 100 ന്‌ of this soil for complete saturation.
Assume G=2.75

2 a) Aclay has a liquid limit of 52% and shrinkage limit of 17%. If a specimen of this 6
soil shrinks from a volume of 10000mm? at liquid limit to 6010 mm? at shrinkage
limit determine the specific gravity of soil grains.

b) Draw LS. Plasticity chart and mark the details. What is its practical application? 9

3 9) Starting from the fundamentals, derive an expression for bulk unit weight in 8
terms of air content, water content and percentage air voids.

b) Why is a deflocculating agent correction needed for observed hydrometer 7
reading? What is the nature of correction [positive or negative]? Mention a
commonly used deflocculating agent.

PART B
Answer any two full questions, each carries 15 marks
4 ஐ. Differentiate between critical hydraulic gradient and exit gradient. 6

b) A sand deposit has: void ratio=0.85; G=2.7. WT is at 1.5m depth below GS and 9
the soil above WT is also fully saturated due to capillarity. Determine the total,
neutral and effective stress at 1.2m and 4.2m beneath the GS.

5 a) Minor and major principal stresses at failure for a sample of soil subjected to 15
triaxial test are 150kPa and 536.6kPa respectively. Determine the angle of
internal friction of this soil, if its cohesion is 25kPa. Also determine (i) the angle

made by the failure plane with the horizontal; and (ii) direction of maximum

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