— Key Laboratory of Safe Mining of Deep Metal Mines, Ministry of Education, Northeastern University, China ... and 50 MPa were conducted by the MTS815 rock mechanics test system. Based on the stress–strain curve, the evolution law of the strength parameters of rock samples with the crack volume strain and energy with the energy …
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— When the temperature is 25 °C, the granite shear strength is 55.24 MPa when the normal stress is 10 MPa, and when the normal stress is 20 MPa, 30 MPa, or 40 MPa, the granite shear strength increases by …
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Page 4 Hoek-Brown criterion for underground mining Table 1.1: Field estimates of uniaxial compressive strength. Grade* Term Uniaxial Comp. Strength (MPa) Point Load Index (MPa) Field estimate of strength Examples R6 Extremely Strong > 250 >10 Specimen can only be chipped with a geological hammer Fresh basalt, chert, diabase, gneiss, granite,
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— For example, needle penetration test is useful to estimate the strength of soft rocks or rocks with a low UCS, while the indentation test and scratch test show a comparably wide range of applicability. Generally, almost all these test methods (except NPT 1) can be used to estimate the strength of rocks with UCS = 10–100 MPa. Thus, the ...
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Abstract We characterized the strength and deformability of Wuyi granite based on Brazilian tests and axisymmetric compression tests under dif-ferent conning pressures (0, 5, 10, 20, 25, and 30 MPa). Facilitated by a modied three-dimensional (3D) Hoek–Brown strength criterion, the 3D strength envelopes of the granite in the principal stress space
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— The progressive brittle failure of high-stress hard surrounding rock masses caused by layered excavation severely threatens the stability of large underground caverns. We summarize the stress path in the potential failure zone of the Shuangjiangkou underground powerhouse during layered excavation, and then design the multistep …
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— The elastic modulus ranges from 9.7 to 144 GPa, the uniaxial compressive strength ranges from 3.1 to 81.2 MPa, the tensile strength ranges from 1.11 to 7.79 MPa, and the average P-wave velocity ...
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— For this reason, fine-grained granite with high brittleness was specially selected. The granite specimens were collected from Hubei Province in Central China. The average bulk density, uniaxial compressive strength, tensile strength and thermal conductivity of granite are 2622 kg/m 3, 217.7 MPa, 11.6 MPa, 2.61W/mK, respectively.
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— 2.2 Laser Irradiation Granite Specimen Test. The laser rock-breaking test platform used in this test is mainly composed of a continuous semiconductor laser and a three-axis CNC cutting platform, and the overall structure is shown in Fig. 2a. The laser has a maximum power of 5 kW and a wavelength of 915 nm, and the CNC cutting platform …
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The average values obtained for the granite samples studied were 86 MPa, 132 MPa and 104 MPa, for collection points 1,2 and 3, respectively. ... View in full-text Get access to 30 million figures
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— To investigate the influence of thermal treatment on the rockburst in granite caverns, true-triaxial compression tests were conducted on pre-heated granite cubic samples containing a circular through-hole using a true-triaxial test system, and the micro camera was used to monitor and record the rockburst process in realtime. Test results …
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Uniaxial compressive strength of stone mine rocks grouped by strength. Group. Average (MPa) Range (MPa) Samples tested Representative limestone formations Lower strength Medium strength High strength 88 135 220; 44–144 82–207 152–301: 50 100 32: Burlington, Salem, Galena-Plattesville
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— The lithology of the HDR reservoir is generally granite buried at a depth below 3 km with high rock mechanical strength, subjected to high in-situ stress and high …
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Question: WORKOUTImmediate roof material in a certain coal mine comprises of a sandstone layer 40cm thick and isoverlain by 1.5m of another rock type more stronper/competent than the sand stone. Sandstone hastensile strength of 5Mpa and density of 2.5tm3.
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The results show that with the increase of SHPB impact pressure (0.5–0.8 MPa), the stress peak values of granite, marble, and limestone also increase, while gypsum and reef …
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Granite dust is a waste material which is produced during crushing and grinding process of granite stone. The annual production rate of the Maddhapara Granite Mine is 1.65 million metric tons from ...
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Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as 3000 MPa for very high-strength steels. Fracture point: The fracture point is the point of strain where the material physically separates. At this point, the strain reaches its maximum value and the material actually fractures, even though the corresponding stress may be ...
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— The modelled strength of the intact granite is 360 MPa at a depth of 1400 m and increases to 455 MPa at 2200 m (using our estimate for the empirical m i term of 30, determined using triaxial and tensile …
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— Granite is one of the rock types commonly encountered in deep mining and used in laboratory experiments [38], [39].Therefore, in this study, a granite collected from Yueyang city, Hunan province, China was used as the test material, and its related fundamental mechanical parameters are listed in Table 1.By using an automatic X-ray …
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— We characterized the strength and deformability of Wuyi granite based on Brazilian tests and axisymmetric compression tests under different confining pressures (0, 5, 10, 20, 25, and 30 MPa). Facilitated by a modified three-dimensional (3D) Hoek–Brown strength criterion, the 3D strength envelopes of the granite in the principal stress space …
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Reliable estimates of the strength and deformation characteristics of rock masses are required for almost any form of analysis used for the design of underground excavations.
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Uniaxial Compressive Strength (MPa) Granite. 100-250. Diorite. 150-300. Diabase. 100-350. Gabbro. 150-300. Basalt. 100-300. Gneiss. 50-200. Marble. 100-250. Slate. 100-200. Quartzite. 150-300. Sandstone. 20 …
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— The difficult-to-break granite, which is common in TBM excavation, mine construction, and oil and gas extraction, is chosen as the test rock sample. The dimension of the rock specimen is 400 mm × 200 mm × 40 mm, and its uniaxial compressive strength is as high as 193.5 MPa, which belongs to the category of extremely hard rock.
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— The 112 point exponential fit yields static fatigue limit for the average-strength specimen at 102 MPA or at 459/0 of strength. The 950 confidence boundaries are quite close at 95-109 MPa. The weakest member of the strength distribution (209 MPa) would eventually fail at 94 MPa between confidence limits of 88 and 100 MPa.
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— 1. Introduction. Deep resources such as oil, gas, and solid mineral have drawn more interest. Generally, the deeper drill is characterized by higher pressure and temperature, which make the drilling and borehole stability harder [1–7].However, in Mexico Bay, North Sea Basin, Sichuan Basin, and the South Sea of China [], for example, the …
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— Strength and dilation of jointed granite specimens in servo-controlled triaxial tests. ... For σ 3 =2 MPa, peak strength for the jointed cores was approximately 50% of that for the intact cores; meanwhile ... Proceedings of the 6th international symposium on ground support in mining and civil engineering construction, Cape Town; 2008, p. 37–60.
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— The analysis in Section 5 demonstrates that the temperature threshold of the tested granite under the confining pressure of 30 MPa is 70 °C, which is similar to the values observed without confining pressure. 45 The AE activity of the Beishan granite measured under high-temperature triaxial compression (P c = 5,10,30 MPa, T = …
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— The results of the strength tests show that granite has the highest mean value of 101.67 MPa for Unconfined Compressive Strength (UCS) test, 6.43 MPa for Point Load test while dolomite has the least mean value of 30.56 MPa for UCS test and 0.95 MPa for Point Load test. ... quarry OLALEYE B M * Department of Mining Engineering, Federal ...
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— Mechanical characteristics during static loading at different confining pressures. Figure 4 presents the stress-strain loading results of the granite sample at different confining pressures. When the applied air pressures are 0.25 MPa, 0.3 MPa, 0.35 MPa, and 0.4 MPa, the maximum strain rate is 125 s −1 and the minimum strain rate is …
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— In the tests, good homogeneity of mechanical behavior of Beishan granite is obtained, with average unaxial compression strength of 161 MPa, and Young's Modulus of 61 GPa.The experimental data indicate that the mechanical performance of Beishan granite is strongly influenced by confining pressure, and the brittle behavior is progressively …
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Dynamic uniaxial compression tests for the Bukit Timah granite in Singapore were conducted at four loading rates (10 0, 10 1, 10 3 and 10 5 MPa/s). It was found that the compressive strength increases from 205 MPa to 235 MPa with loading rate increasing from 10 0 to 10 5 MPa/s. Evidence also indicates that there are small changes in the Young's …
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— As shown in Fig. 13 (a), the shear strength of granite samples generally decreases as the joint persistency is varied from 0.0 to 0.90, through 0.25, 0.50 and 0.75. For example, when the joint persistency, k, is 0.0, which means that the granite sample is intact, the shear strength value is 14.70 MPa. With the joint persistency increasing to 0. ...
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solidified lava or "magma" i.e. granite Sedimentary rocks - formed by deposition ... Rock excavation method according to compressive rock strength 0 20 Compressive rock strength (MPa) 40 60 80 100 120 140 160 180 200 220 240 260 12. ... have mining with the aim of extracting minerals from underground. At first, we excavate (non-valuable) waste ...
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— The tensile failure is a common failure pattern of rock and its tensile strength is a very important parameter in assessing and controlling the stability of rock engineering (Wu et al. 2009; Huang and Huang 2014; Huang and Li 2014).Furthermore, there are many tensile failures of rock occurring under confining pressure, such as the mining-induced …
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