Question 1 |

The inside diameter of a sampler tube is 50 mm. The inside diameter of the
cutting edge is kept such that the Inside Clearance Ratio (ICR) is 1.0% to
minimize the friction on the sample as the sampler tube enters into the soil.

The inside diameter (in mm) of the cutting edge is ________. (round off to two decimal places)

The inside diameter (in mm) of the cutting edge is ________. (round off to two decimal places)

49.52 | |

25.36 | |

42.25 | |

36.32 |

Question 1 Explanation:

Moisture content

\begin{aligned} C_i&=\frac{D_3-D-1}{D_1} \times 100\\ 1&=\frac{50-D_1}{D_1} \times 100\\ D_1&=49.50mm \end{aligned}

Question 2 |

In a soil investigation work at a site, Standard Penetration Test (SPT) was conducted
at every 1.5 m interval up to 30 m depth. At 3 m depth, the observed number of hammer
blows for three successive 150 mm penetrations were 8, 6 and 9, respectively. The SPT N-value at 3 m depth, is

23 | |

17 | |

15 | |

14 |

Question 2 Explanation:

No. of blows for each 150 mm penetration 8, 6 and 9.

We will not consider first 150 mm number of blows.

Hence, for last 300 mm, number of blows are 15.

Hence, observed SPT number = 15.

We will not consider first 150 mm number of blows.

Hence, for last 300 mm, number of blows are 15.

Hence, observed SPT number = 15.

Question 3 |

For the following statements:

P: The lateral stress in the soil while being tested in an oedometer is always at-rest.

Q: For a perfectly rigid strip footing at deeper depths in a sand deposit, the vertical normal contact stress at the footing edge is greater than that at its centre.

R: The corrections for overburden pressure and dilatancy are not applied to measured SPT-N values in case of clay deposits.

The correct combination of the statements is

P: The lateral stress in the soil while being tested in an oedometer is always at-rest.

Q: For a perfectly rigid strip footing at deeper depths in a sand deposit, the vertical normal contact stress at the footing edge is greater than that at its centre.

R: The corrections for overburden pressure and dilatancy are not applied to measured SPT-N values in case of clay deposits.

The correct combination of the statements is

P -TRUE; Q -TRUE; R -TRUE | |

P -FALSE; Q -FALSE; R -TRUE | |

P -TRUE; Q -TRUE; R -FALSE | |

P -FALSE; Q -FALSE; R -FALSE |

Question 3 Explanation:

P: True

In the Oedometer test, stress is applied to the soil specimen along the vertical axis, while strain in the horizontal direction is prevented by the confining ring (a condition of zero lateral strain). Thus it simulates at-rest condition.

Q: True

For a perfectly rigid footing resting on surface of sand deposit, the contact pressure distribution is zero at the edges and maximum at centre. However, for a very deep rigid footing on sand, the contact pressure distribution may tend to become like that of rigid footing on clayey soil, with edge contact stress greater than at its centre.

R: True

For cohesive soil, there is no need for overburden pressure correction (Peck et al 1974). For cohesionless soil at first overburden pressure correction is made, then if it is fine sand or silt under water table with N-value \gt 15, dilatancy correction is made.

In the Oedometer test, stress is applied to the soil specimen along the vertical axis, while strain in the horizontal direction is prevented by the confining ring (a condition of zero lateral strain). Thus it simulates at-rest condition.

Q: True

For a perfectly rigid footing resting on surface of sand deposit, the contact pressure distribution is zero at the edges and maximum at centre. However, for a very deep rigid footing on sand, the contact pressure distribution may tend to become like that of rigid footing on clayey soil, with edge contact stress greater than at its centre.

R: True

For cohesive soil, there is no need for overburden pressure correction (Peck et al 1974). For cohesionless soil at first overburden pressure correction is made, then if it is fine sand or silt under water table with N-value \gt 15, dilatancy correction is made.

Question 4 |

Which of the following statement is TRUE for degree of disturbance of collected soil sample?

Thinner the sampler wall, lower the degree of disturbance of collected soil sample | |

Thicker the sampler wall, lower the degree of disturbance of collected soil sample | |

Thickness of the sampler wall and the degree of disturbance of collected soil sample are unrelated | |

The degree of disturbance of collected soil sample is proportional to the inner diameter of the sampling tube |

Question 4 Explanation:

As thickness of sampler increase, disturbance increase

Question 5 |

The degree of disturbance of the sample collected by the sampler is expressed by a term called the "area ratio". If the outer diameter and inner diameter of the sampler are D_{o} and D_{i} respectively, the area ratio is given by

\frac{D_{o}^{2}-D_{i}^{2}}{D_{i}^{2}} | |

\frac{D_{i}^{2}-D_{o}^{2}}{D_{i}^{2}} | |

\frac{D_{o}^{2}-D_{i}^{2}}{D_{o}^{2}} | |

\frac{D_{i}^{2}-D_{o}^{2}}{D_{o}^{2}} |

There are 5 questions to complete.