Question Paper: Geotechnical Engg 1 Question Paper - Jun 17 - Civil Engineering (Semester 5) - Mumbai University (MU)

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## Geotechnical Engg 1 - Jun 17

### Civil Engineering (Semester 5)

Total marks: 80

Total time: 3 Hours
INSTRUCTIONS

(1) Question 1 is compulsory.

(2) Attempt any **three** from the remaining questions.

(3) Draw neat diagrams wherever necessary.

**1.a.**Write characterisitics of flow net.

**1.b.**What do you mean by borehole logs? Write at least five number of information which it reflects.

**1.c.**Write the use of particle size distribution curve.

**1.d.**Explain the factors affecting the permeability of soil.

**2.a.**Explain how to determine the preconsolidation pressure by Cassgrande method.

**2.b.**A moist soil has weight of 1260 gms and volume of 605 cc at a moisture content of 11%. If the specific gravity of the soil grain is 2.66, determine the void ratio, degree of saturation, and percentage air voids.

**2.c.**Establish the relationship between $\sigma_{1}, \sigma_{3}, c_{1}$ and $\phi$

**3.a.**In a liquid limit test, specimen of a certain sample of clay at water contents of 31.93, 27.62, 25.51 and 23.30 % required 5, 16, 23, and 42 blows respectively to close the standard groove. The plastic limit of clay is 13%. Natural water content is 18% . Determine the liquid limit, plasticity index, liquidity index, consistency index, flow index and toughness index.

**3.b.**Explain the primary consolidation by spring analogy system.

**3.c.**For two soils the data is given as below. Classify the soil as per IS: 1498.

Soil | LL | PI | $\%-75 \mu$ | % Gravel | % Sand |
---|---|---|---|---|---|

A | 60 | 30 | 90 | 0 | 10 |

B | - | NP | 100 | 0 | 0 |

**4.a.**In a falling head permeability test on a soil sample of length $1_{1}$ head of water in the stand pipe takes 5 seconds to fall from 900 mm to 135 mm above the tail water level. When another soil of length 60 mm is placed on top of first soil, the time taken for the head to fall between the same limits in 150 seconds. The permeameter has a cross sectional area of Calculate the permeability of second soil.

**4.b.**Write a note on methods of boring.

**4.c.**Explain the quick sand condition and derive an expression for same.

**5.a.**Define reinforcing earth material. Classify the Geosynthetics and Geotextile.

**5.b.**Write a brief note on factors affecting the compaction.

**5.c.**Given the following data from a consolidated undrained test with pore water pressure measurement, determine the total and effective stress parameters.

$\sigma_{3}$ | 100 $\mathrm{kN} / \mathrm{m}^{2}$ | 200$\cdot \mathrm{kN} / \mathrm{m}^{2}$ |
---|---|---|

$\left(\sigma_{1},-\sigma_{3}\right)_{t}$ | 156 $\mathrm{kN} / \mathrm{m}^{2}$ | 198 $\mathrm{kN} / \mathrm{m}^{2}$ |

$\mathrm{u}_{\mathrm{f}}$ | 58 $\mathrm{kN} / \mathrm{m}^{2}$ | 138$\cdot \mathrm{kN} / \mathrm{m}^{2}$ |

**6.a.**In a normally consolidated clay of LL = 65.65% and 5 m thickness, the overburden pressure is increased from 250 $\mathrm{kN} / \mathrm{m}^{2} \mathrm{by} 120 \mathrm{kN} / \mathrm{m}^{2}$ Estimate the settlement that takes place; assume the saturated water content and specific gravit of solid are 45% and 2.7 respectively.

**6.b.**Explain the effect of surcharge and capillary rise on effective pressure.

**6.c.**Write scope of Geotechnical Engineering in design of deep foundation. Write five points.

**6.d.**Explain the applicability of plasticity char [as per [SCS] in classifying the fine grained soil and how it differs from USCS.