GATE MN Geomechanics PYQs & Answers — Page 3

Questions 21–30 of 58. Imported answers require independent review unless marked reviewed.

Topic practice 58 questionsPage 3 of 6

A slope stability radar shows that the position of a point P in a mine dump shifts from (200, 700, −60) m to (200.05, 700.1, −60.75) m over a time

. The net displacement in cm of the point P is_____. [rounded off to 2 decimal places]

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A Mohr-Coulomb failure envelope of a sandstone rock is given as

where

and

, measured in MPa, are the major and minor principal stresses respectively. The angle of the failure plane with the

axis in degree is_____. [rounded off to 1 decimal place]

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‘Critical subsidence’ has occurred on the surface due to mining of a flat longwall panel at a depth of 200 m. The width of the panel is 150 m. The maximum width of the panel in m that can be mined at a depth of 300 m, to reach critical subsidence is_____. [rounded off to 1 decimal place]

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A circular tunnel is developed in a biaxial in situ stress field as shown in the figure. If the ratio between tangential stress at the boundary point A and that at the boundary point B is 2.0, the value of k is _____.

[rounded off to 2 decimal places]

Diagram for Mining Engineering question 47

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Stress waves are sent from the transmitter A to the receiver B through an isotropic and elastic cylindrical rock specimen as shown in the figure.

The length of the specimen is 100 mm. The travel time of longitudinal and shear waves are 0.025 ms and 0.04 ms, respectively. The Poisson’s ratio of the rock specimen is _____.

[rounded off to 2 decimal places]

Diagram for Mining Engineering question 50

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A jointed rock sample is subjected to 20 MPa vertical stress as shown in the figure.

The modulus of elasticity of the rock is 10 GPa and the normal stiffness of the joint surface is 5 GPa/m. Assuming one-dimensional elastic behavior of rock and joint, the displacement in mm of the loading surface AB is _____.

[rounded off to 1 decimal place]

Diagram for Mining Engineering question 51

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An irregular shaped rock sample of mass 60 g displaces 27 g of brine when submerged in a filled jar. The specific gravity of brine is 1.05. The unit weight of the rock sample in kN/m³ is _____.

[rounded off to 2 decimal places]

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A rock slope is intercepted by a joint plane at an angle 30° as shown in figure.

Diagram for Mining Engineering question 62

The following data are available

Unit weight of the rock : 20 kN/m³ Cohesion of joint : 30 kPa Friction angle of joint : 22°

The factor of safety of the rock slope to slide along the joint plane is _____.

[rounded off to 2 decimal places]

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Water flows through a vertical sand column of cross sectional area 400 mm² and length 300 mm. For a water head of 600 mm, quantity of seepage water is 100 mm³/min. The hydraulic conductivity of the sand column, in mm/min is ______. (round off to three decimal places)

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The modified Lauffer diagram as shown in the figure relates to roof span, RMR and stand-up time. In a metal mine, roof span of a drive is 4 m. If the RMR of the rock mass changes from 40 to 60, then the stand-up time increases by a factor of ______. (round off to two decimal places)

Diagram for Mining Engineering question 33

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GATE MN Geomechanics PYQs

Question 29

Question 30

Question 32

Question 47

Question 50

Question 51

Question 53

Question 62

Question 32

Question 33