Identify from below the advantage of steel support over timber support
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Mining Engineering · all questionsRock Mechanics and Roof Supporting
Rock Mechanics and Roof Supporting
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A core sample of 54 mm diameter having Young's modulus of 68.97 Gpa fails in uniaxial compression at 0.1% axial strain. The axial load at failure in kN is
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The instrument Flat jack is used for measuring the
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Correlation between the rock mass classification systems of RMR and Q is
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Chockmate is used in metal mines. Which of the following coal mine support is similar to chockmate?
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As per DGMS Circular 7/2002, who out of the following shall be responsible to assess the requirements of support in underground?
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The uniaxial compressive strength of a limestone sample is 80 MPa. The sample is confined at a pressure of 20 MPa in a triaxial compressive strength test. Based on Hoek-Brown failure criteria the maximum principal stress at failure in MPa is
(Consider rock constants as m = 7.88, s = 1.0 and a = 0.5)
(Consider rock constants as m = 7.88, s = 1.0 and a = 0.5)
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A rock specimen of 120 mm length and 54 mm diameter is subjected to uniaxial compressive loading. Two strain gauges, one axially and other radially, are attached to the specimen. At the breaking load, if these two gauges read 0.0082 m/m and 0.0023 m/m respectively, the Poisson's ratio of the specimen is
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Powered support is used in
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Which of the following bolting density has been prescribed for poor types of roof?
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Computational methods of stress analysis fall into two distinct categories - one of them is intregral, what is the other?
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Which of the following cell is sometimes used to investigate the shear behaviour of discontinuities?
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For a typical hard rock with E = 105 Mpa and Poisson's ratio = 0.25, the modulus of rigidity in GPa is
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What do you mean by effective stress?
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In freshly exposed roof area of developing working, which of the following support should be preferably used?
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Which of the following may be called as quick setting support?
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What will be safe cover i.e. the tolerance limit for extraction of coal pillars with caving where railway line is on the surface? T is the seam thickness in meter
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A series of tri-axial compression tests conducted on sandstone samples reveal the following relationship between major and minor principal stresses σ1 = 50 + 30σ3 [stresses are in MPa)
The cohesion in MPa and angle of internal friction in degrees of sandstone respectively are
The cohesion in MPa and angle of internal friction in degrees of sandstone respectively are
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A tension crack of 5 m depth behind a rock slope crest is completely filled with water. What is the horizontal force exerted on a unit slope length by the water in the tension crack?
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"A crack will extend only when the total potential energy of the system of applied forces and material decreases or remain constant with an increase in crack length" - Who has given this concept?
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