From the alternating-sign explosion response of rocks to the pendulum waves in stressed geomedia. Part IV

The scope of this expert and analytical review encompasses major achievements in the area of nonlinear geomechanics, geophysics, geomonitoring and advanced information technologies with a view to developing the natural and induced emergency prevention and response technology listed among the “national critical technologies” in the Russian Federation. The topical trends of the related R&D activities are basic research in physics and geomechanics of natural and induced failure source formation and growth in rocks and in mines, and creation of multi-layer geoinformation monitoring system for geomechanical and geodynamic safety in Russia. The authors believe that the described R&D activities may be the basis for an international multidisciplinary mega-project in geosciences: Engineering and Creation of the World’s Multi- Layer Geomechanical, Geodynamic and Environmental Safety Geoinformation Monitoring System.     

Basis of borehole radiometric defectoscopy for rocks. Part II. Physical modeling

Conclusions We have shown that the distance between cracks can be determined from the distance between the maxima of radiometric logs. With a reduction in probe base there is an increase in the absolute maximum of the anomaly I_γmax with a simultaneous reduction in its width. The width of the maximum I_γmax of the anomaly equals the sum of the probe base and crack opening lengths. Physical and mathematical modeling demonstrates the identical qualitative dependence of recorded γ-radiation on crack parameters. However, in arranging problems of mathematical modeling it is necessary to carry out a laboratory experiment previously with the aim of eliminating unmonitored parameters. The possibility has been demonstrated of using hypotheses 1–4, which lie at the base of a theory for borehole geophysical defectoscopy, for interpreting gamma-gamma ray logging data. Institute of Mining, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Fiziko-tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 35–40, September–October, 1990.     

Geological factors governing the stressed state of the rocks

Journal of Mining Science -     

Pendulum-type waves. Part II: Experimental methods and main results of physical modeling

Conclusions 1. Investigations of physical modeling of pulsed actions on models of block media (with different material composition and characteristic dimensions of the subblocks) by energy-calibrated impacts confirmed the hypothesis expressed earlier by the authors about the possibility of existence of pendulum-type waves, the elementary carriers of which are geoblocks of a different scale level (-waves).2. An analysis of the regularities of formation of the spectra of the wave packets and graphs of the absolute displacements of the blocks, determined by the optical method, permitted concluding a resonance mechanism of occurrence of -waves, underlying which is the canonical relationship of the spectral modes for wave packets with respect to factor (2)ⁱ, i=0, ±1, ±2, ±3, ... .3. The effect of the condition of canonical relationship of the spectrum in wave packets of -waves under certain conditions of energy actions can leads to the occurrence of the effect of anomalously low friction between interacting blocks (carriers of -waves) in directions orthogonal to the line of action of the external pulse.The work was performed with the financial support of the Russian basic research fund (grant No. 96-05-66052).Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 3–39, July–August, 1996.     

Attenuation and change in the shape of stress waves in rocks

Mining Institute, St. Petersburg. Translated from Fiziko-Technicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 38–41, July–August, 1992.     

Analysis of the dynamics of two-way hydropercussion systems. Part II: Influence of design factors and their interaction with rocks

The mathematical model of two-way hydropercussion system considers design philosophy of the system and its interaction with rocks. The author analyzes numerically effect of design factors on dynamics and integral output capability of limit cycles.     

Effect of deformation properties of discontinuities on intensity of induced seismicity sources in rocks. Part II: laboratory and numerical experiments

Variations in strength and stress state of rocks fail to explain the difference observed in efficiency of seismic radiation from separate sources within the limits of the same mine field. The laboratory and numerical experiments show that insignificant variation in ultimate strength of a fracture and, thus, different shear fracture stiffness results in radical change in the seismic event efficiency. The experimentally obtained relations between the key parameters should be taken into account in geomechanical modeling of large-scale objects.     

Effect of viscosity of partings in block-hierarchical media on propagation of low-frequency pendulum waves

The study focuses on the pendulum-type wave propagation in an assembly of steel rods parted alternatively by rubber and foam plastic and exposed to impulse loading. The proposed numerical model describes this system as a chain of masses linked by elastic springs and viscous damping elements. At large times from the loading onset, the asymptotical estimates of velocities and accelerations of the masses are obtained. The numerical calculations, analytical solutions and experimental data are compared, and the domain of applicability of the analytical evaluations is delimited. The authors show that this model adequately describes perturbations in the system of rods with alternating visco-elastic partings. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 3–13, May–June, 2008.