Which of the following is not a contributory factor for the cause of the subsidence?
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Mining Engineering · all questionsRock Mechanics and Roof Supporting
Rock Mechanics and Roof Supporting
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The pressure on a phreatic surface is
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It is an electrical resistance thermometer made from a semi-conductor having a large, negative temperature co-efficient useful to measure the rock temperature
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Support plan of any underground mine shall be approved by
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In order to maintain contact with the immediate roof, laggings are put with the cross-bars. The norms of putting such laggings is
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The uni-axial compressive strength and modulus of elasticity of a rock sample are 90 MPa and 30 GPa respectively. The stored strain energy per unit volume in kN.m/m3 of the sample at the time of failure is
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The ratio of uniaxial compressive strength to uniaxial tensile strength of a sandstone specimen is 8 : 1. The theoretical, value of angle of internal friction of the specimen in degree is
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In a point load test on 50 mm diameter core specimen. rupture was observed at a load of 5000 kg. The uni-axial compressive strength of the specimen was
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After every round of blasting, support of roof and sides shall be tested at places within the zone of influence of blasting. Who decides this zone?
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The specific gravity of gypsum mineral is 2.4. If the density of a gypsum core is 2100 kg/m3, the porosity of that core is
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If a rock type has RMR value 70, then what will be its roof class?
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The measurements of a site investigation are as follows:
In = 9, Jr = 1.5, Ja = 2.0, Jw = 1.0. SRF = 2.5. The RQD values taken from five boreholes of the area are 94.2, 95.6, 99.4, 95.3 and 98.0 respectively. The rock mass quality index (Q) is
In = 9, Jr = 1.5, Ja = 2.0, Jw = 1.0. SRF = 2.5. The RQD values taken from five boreholes of the area are 94.2, 95.6, 99.4, 95.3 and 98.0 respectively. The rock mass quality index (Q) is
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The objective of such activity is to restrict displacements of the country rock to elastic orders of magnitude and to maintain as far as practicable the integrity of both the country rock and the unmined remnants within the ore body. Identify the mining activity?
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During uniaxial compressive testing of a rock specimen of diameter 54 mm and length 120 mm, the axial strain was found to be 6.5 × 10-4 mm/mm. If the Poisson's ratio of the rock is 0.3, the volumetric strain of the rock specimen in mm/mm is
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From a series of tri-axial tests conducted on some sandstone specimens, the relationship between the major and the minor principal stresses in MPa is found to be σ1 = 100 + 5 σ3. The angle of internal friction in degrees of that sandstone is
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The components of state of stress at a point in x - y plane are given as σxx = 5 MPa, σyy = 10MPA and = 2MPa. The sum of the principal stresses acting on the x - y plane in MPa is
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