Mechanical properties of the principal rock-forming minerals of the Khibiny apatite — nepheline deposits

Conclusions This elastic properties of minerals depend on structural elements (continuous chains, bands, framework structure), and the strength properties also depend on the nonuniformity of the structure (cleavage, joints, inclusions); fracture takes place at the surfaces of these nonuniformities. The maximum values of the strength properties of minerals without cleavage (apatite and nepheline) coincide with the direction of the maximal strength properties, namely. [001]. A similar regularity isobserved for aegirite—diopside because its most pronounced cleavage is not exhibited in the principal crystallographic directions. Microcline—perthite with maximal elastic properties in the [010] direction has minimal tensile strength in this direction, because perfect cleavage is observed in the latter. Inclusions in the crystals promote local stress concentrations and more rapid fracture; higher strengths are therefore observed for crystals with few or no inclusions. Anisotropy of the strength properties is most marked (up to 60%) for minerals with poorer symmetry and more developed cleavage (microcline—perthite and aegirite—diopside). For the minerals investigated a linear dependence is observed between the stresses and deformation up to fracture. For monomineralic aggregates the appearance of plastic deformations is observed at loads usually amounting to 30–70% of the breaking loads, owing to an increase in the number of nonuniformities in the rocks and to the sharp outlines of the grains of these aggregates. This also explains why the indices of the mechanical properties are lower than those of single crystals by a factor of 1.5–3. The mechanical characteristics of the minerals enable us to assess the properties of the corresponding monomineralic aggregates and to establish the dependence of the properties of the rocks on the mineralogical composition. Mining-Metallurgical Institute, Apatity. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 10–15, September–October, 1974.     

Simplified method for determining the extent to which strain rate affects the strength and energy capacity of rock fracture

Conclusions The described method of determining the extent to which strain rate affects the energy capacity of rock fracture offers a number of advantages over the traditional method: Firstly, it enables us to reduce the number of specimens tested by at least a factor of two; secondly, it increases the validity of the conclusions, since two forms of activity (static and dynamic) are applied to the same specimen; and, thirdly, it makes it possible to evaluate the effect of strain rate on the energy capacity of fracture for rocks where twin specimens have a high scatter of mechanical characteristics. Mining Institute, Leningrad. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 29–35, July–August, 1990.     

Mechanical Properties of Carboniferous Rocks in the Upper Silesian Coal Basin under Uniaxial and Triaxial Compression Tests

Many years' studies of geological properties or rocks from the Upper Silesian Coal Basin have resulted in acquisition of a substantial data base of mechanical parameters or rocks over the total strain range. It is found that the post-peak rock properties are closely related with the peak strength and the pre-peak properties. The relationship between the uniaxial ultimate strength, elastic modulus, and drop modulus are determined. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 44–48, March–April, 2005.     

Rock drillability classification. Part II: Canonical representation of rock properties in the rock classification by fracture resistance

A multifactor classification of rocks by drillability is proposed based on canonical representation of the mechanical and structural properties of rocks by the dimensionless characteristics of rock fracture resistance. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 6. pp. 86–104, November–December, 2008.     

Mechanical triaxial compression machines

The author describes the design of the mechanical triaxial compression machine, its capabilities, test procedure and data processing results, and some of metrology issues. The machine approval on fracture sand-and-clay rocks is exemplified. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 111–119, July–August, 2008.     

Specific Energy Prediction for Circular Diamond Saw in Cutting Different Types of Rocks Using Multivariable Linear Regression Analysis

Circular diamond saw performance is affected by a variety of factors. The principal factors requiring consideration when predicting cutting rates are the type and operating features of a diamond saw and the rock characteristics. The laboratory experimental tests are carried out on three groups of rocks (16 types) cut with the help of three types of diamond disk saws with different feed rates and cutting depths at constant peripheral velocity. The quantitative determinations of a wide range of textural, mechanical, and intact properties of rocks are also made. The relationship between the specific cutting energy SE _cut of the sawblade operating parameters and rock properties is established. Applying multivariable linear regression analysis, the predictive model of SE _cut is developed based on the rock property data. Models verified by statistical tests prove their practical validity. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 56–80, May–June, 2005.     

Energy content of the nonexplosive excavation of rock by excavators with a dynamic scoop

Conclusions  

X型共轭剪切破裂-地震产生的力学机理及其演化规律

地震的发生是一个极为复杂且高度非线性的物理过程,基于乔建永、马念杰、马骥等提出的X型共轭剪切破裂-地震复合模型,进一步研究了共轭剪切破裂-地震发生的力学机理,阐明了共轭剪切破裂-地震发生及其演化的物理过程,从软弱异性体周围岩体应力、破坏形态与地震能量变化的角度出发,发现了共轭剪切破裂-地震具有"仿蝶存亡"规律,获得了共轭剪切破裂-地震生成的必要条件。研究结果表明:由于构造应力显现区域应力环境的剧烈变化,地壳岩体中会形成以软弱异性体为中心的性态极不稳定的蝶形破坏区,它的扩展最终会形成显性或隐性的共轭剪切破裂;蝶形破坏区蝶叶每次扩展释放的能量会在一定范围内引发地震,即地震是触发事件动载作用下蝶形破坏瞬态扩展所释放弹性能的非线性动力现象;共轭剪切破裂在不同应力状态下经历了圆形和椭圆形破坏、蝶形渐进破坏与蝶形剧烈破坏的孕育期、生长期与剧变期;依据地震里氏震级的强弱,在共轭剪切破裂动态生成过程中地震活动存在着弱震期,中强震期与强震期的"仿蝶存亡"特点;共轭剪切破裂—地震发生的必要条件主要有地壳中的软弱异性体存在条件,构造应力剧烈变化条件,软弱异性体及其周围岩体强度条件以及地震发生的应力触发条件。     

Identification of stresses in rocks on the basis of changes in density of infrared radiation flux

The efficiency of infrared radiometry as a source of information on changes in the stress state of rocks is substantiated experimentally. The experiments were conducted under conditions of pulse actions. An analysis of synchronized records of the mechanical state of the specimen and the corresponding variations in the intensity of heat flux from its surface shows the reliability of recording and evaluating “jumps” in stresses on the basis of radiometric data. The Gersevanov Scientific-Research Institute of Foundations and Underground Structures, Moscow. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 6, pp. 48–53, November–December, 1999.     

Impulsive liquid-gas fracture of brittle and ductile rocks and ways of improving the process

Conclusions 1. Other conditions being equal, an increase in the strength and fracture toughness of rock reduces mean crack velocity in impulsive hydraulic fracture and the final dimensions of the cracks within the loading-rate range 0.5·10⁹≤ ≤5·10⁹ Pa/sec. 2. Since the drag coefficient of fluid in a crack is determined by the roughness of the crack’s walls, other conditions being equal, the greatest effect from impulsive fracture should be seen in rocks with fine and cryptocrystalline structures. 3. If the coefficient that characterizes the degree to which a well is filled by combustible material is increased in value from 0.62 to 0.75, the dize of the disk-shaped tensile ruptures formed in ductile rocks increases 60–70%. 4. The main parameters characterizing the impulsive fracture of a productive bed (crack depth and width) depend more on the thermodynamic characteristics of the pressure generator in the well (injection time and pressure) than on the viscosity of the injected fluid. 5. A technology involving interval-by-interval impulsive fracture by sectional shaped charges of high explosives is recommended for strong brittle rocks of moderate and high density. Institute of Geophysics, National Academy of Sciences of the Ukraine (Kiev). Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 50–58, July–August, 1997.     

Gradient approach to rock strength estimation

The possibility of application of the gradient approach to rock strength estimation is considered in the case when the mechanical properties of the rocks change as a result of stress concentration close to rock structure defects, cavities, and mine workings. A criterion of shear crack appearance is proposed, and expressions for the critical stresses are obtained. Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences, Yakutsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 54–60, July–August, 1999.     

Anomalies of low-intensity acoustic wave attenuation in rocks

It is experimentally established that acoustic waves in rocks attenuate abnormally depending on varying amplitude. The amplitude growth results in the increase in elastic wave velocities and decrease in the attenuation decrement. The attenuation rather than wave velocity is more sensitive to the amplitude variations. The obtained data are applicable to diagnose the states of fractured and porous rocks. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 24–31, July–August, 2008.     

Mechanism of wall caving in Muruntau open pit mine

Interrelation between movements in walls of an open pit mine and formation of fracture pattern in host rocks is considered. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 62–71, September–October, 2008.     

Character of strengthening of an initially orthotropic material when subjected to simple and complex loadings. Communication 3: Experimental study of mechanical anisotropy

The results of an investigation into plastic deformation of titanium alloy with initially anisotropic elastic mechanical characteristics are presented. The limit of applicability of classical plasticity theories for complex loadings is determined. A rating dependence is plotted in generalized coordinates: principal tangential stress and principal shear strain. Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 6, pp. 3–9, November–December, 1999.     

Turboblasting explosive charges. III: Profile of the detonation reaction path

The detonation of individual solid explosives of C_aH_bO_cN_d type is described by introducing the concept of a nonthermal potential as the sum of several types of energy—chemical energy, elastic compression, the electron state of the molecules, and the kinetic energy of the flux. Graphs of the variation in the nonthermal potential and the internal energy of the substance, the kinetic energy of the flux, and the pressure in the head region of the detonation wave right up to the Chapman-Jouguet plane are plotted. The relations between the various types of works performed at the shock front are calculated. Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk. Translated from Fiziko-Tekhnichskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 60–71, March–April, 1999.     

Electric-discharge cutting of rocks

The test data are reported on rock cutting by the electric discharge with movable and stationary electrodes. The specific crushing energy is determined, the electrode system design is optimized, and the high-voltage impulse parameters selected for highly efficient fracture. The study results make the grounds to develop an electric-discharge cutter for rocks and concrete. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 70–77, March-April, 2008.     

Energy flux lines in a deformable rock mass with elliptical openings

The stress-strain state of an elastic plane with elliptical cuts is studied under different loading conditions. The lines of an energy flux are constructed. It is shown that energy transmission into a deformable medium is induced exclusively by external forces applied. The effect of boundary conditions on the energy flux lines is demonstrated. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 3–8, May–June, 2009.     

西部弱胶结砂岩循环载荷作用下塑性应变能变化规律

通过不同应力路径下的三轴循环加卸载实验,对中国西部矿区中不同粒径弱胶结砂岩的塑性应变能和塑性变形变化规律进行了研究。实验结果表明,加载路径对砂岩的塑性应变能及塑性变形特征有显著影响;在加载过程中,粗砂,中砂,细砂储存的塑性应变能以及累计速度依次递减,并且塑性应变能随应力增大按指数规律变化;各加卸载周期内储存的塑性应变能随加卸载次数及应力的增大呈“U”字形变化,即初始阶段由于孔隙裂隙压密,会储存较多塑性应变能;弹性阶段变形源于晶格弹性压缩,卸载时可以恢复,储存的塑性应变能较少;屈服阶段由于破裂面滑移也会储存较多塑性应变能;轴向和径向残余应变随应力增大呈指数形式增长,并且径向残余应变增长速度大于轴向;残余应变与塑性应变能变化规律不同,塑性应变能更能真实反映岩石在受载过程中的状态变化。     

Working hard rocks with a bucket-wheel excavator

Summary During excavation of hard rocks, as in that of cohesive soils, the required cutting force rises linearly with the thickness and cross-sectional area of the slice, while the specific cutting force K_f and specific energy consumption of the excavation process decrease according to a hyperbolic law. Increase of the platform rotation rate, and hence of the slice width, within the rated speed regulation limits (20–30 m/min), causes a slight increase in the cutting force. The energy consumption of coal cutting in horizontal slices is about 20% higher than when the excavator wor in vertical slices. During excavation of horizontal slices, the dynamicity coefficient and nonuniformity of load application are 15 and 25% higher, respectively. The lateral component of the cutting force averages 0.1–0.4 of the peripheral component, and in certain case reaches 0.5–0.6. Large values of the lateral component of the cutting force correspond to the excavation of thin horizontal slices. The radial component of the cutting force is 30–100% of the peripheral component, while its maximum value reaches 140–180%. The peripheral component of the cutting force per single bucket varies with underbench height in accordance with the theoretical law; maximum cutting force is reached at the moment when the slice is being cut level with the rotor axis. The duration of action of the cutting force also approximately corresponds with the theoretical value but is limited by the actual angle of contact with the face. Central Communications Scientific Research Institute, Moscow. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 64–68, January–February, 1968.     

Nonlinear effects in the radiation and propagation of vibro-seismic signals in a rock mass

Results are presented from measurements of the vibro-seismic field of a surface source in a rock mass at depths of up to 1.5 km. Effects connected with the grouping of sources are examined along with the transformation of the signal spectrum during passage through an oil stratum. It is shown that the absorption coefficient of vibro-seismic monochromatic signals by sedimentary rocks is within the range 0.63–0.75 dB/λ_p, where λ_p is the length of the longitudinal waves. Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 3–10, March–April, 1999.