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This paper describes a fiber-optic transmission system for access networks with frequency division of channels formed in optical, microwave, and radio frequency ranges. The single-band optical modulation and different formats of modulation of subcarrier channels are studied. The calculated expressions for estimating the number of spectral and subcarrier channels in view of the effect of stimulated Raman scattering (Raman effect) and optical preamplifier noise are presented

The article puts forward a procedure to determine structure and physico-mechanical properties of near-surface cohesive soil based on seismic surveying. The backbone of the approach is the use of distribution of P- and S-waves obtained from combination of the seismic refraction technique modification and the multi-channel surface wave analysis. The recovery of the physico-mechanical properties uses correlation dependences. The authors give an example of field data processing. The field research covered a section of a motor road where groundwater level is determined and zones subjected to washout and deformation are detected.

The authors model deformation and mass transfer in jointed and porous rock mass around a production well. The modeling based on the concept of a continuum with double porosity uses an original method with finite difference solution of mass transfer equations and analytical solution of pore elastoplasticity equations. From the numerical experiments, dimensions of irreversible straining zones in the well bore zone grow with the parameter Bio. The estimate of the reservoir permeability decline in the course of operation, obtained from the pore elasticity and pore plasticity models, qualitatively agrees with the in situ observation data.

The practical calculation of rock mass deformation around an underground opening accounts for the weight of rock mass by solving a complimentary problem on “weightless” rock mass. A domain with an opening is bounded by a plane with the preset zero vertical displacements, which enables taking into account difference of pressure along the height of the opening. This solution, with the adequately selected boundary conditions, is added with stress field of an intact rock mass and offers zero boundary conditions at the future opening perimeter, however, the issue on the validity of setting boundary conditions at the lower boundary of the calculation domain remains yet to be handled. This article presents a phenomenological model of rock mass deformation to answer the set question. It is taken into account that action of roof rock weight coincides with the orientation of tensile stresses at the opening perimeter and differs from it in the floor. The author thinks it is required to add the class of inverse problems of rock mechanics with the problems directly accounting for rock weight.

The authors present studies into geomechanics of Berezitovoe gold-polymetal deposit at the stage of transition from open pit to underground mining. The authors have carried out geodynamic zoning and evaluated parameters of modern stress field. Rock mass ratings are used to assess physico-mechanical properties of rocks. Rock mass stress state at various stages of mining is examined using numerical modeling, and underground mining system parameters are evaluated using Mathews procedure and analytical relations.

The author offers a new deformation criterion for the compressive strength of salt rock specimens. The limiting principal strain is a function of stress parameter in the form of a ratio of hydrostatic pressure and stress intensity. The safety factor based on the deformation criterion is defined. The numerical modeling of experimental compression of various geometry specimens produces the deformation criterion for sylvinite and carnallite of Upper Kama deposit. The offered criterion is applicable to assessment of load-bearing capacity of stopes in salt rocks.

The scope of the discussion covers the issues of open pit mining efficiency and safety with dry overburden dumping over clayey alluvium. The stress analysis of a dump at Kedrovsky open pit mine uses finite element modeling of linearly deformable medium based on geotechnical, surveying and hydromechanical data. The modeling produces the field of displacements of the dump and its base and the distribution of the Mohr-Coulomb strength criterion. The clayey rock breakout-hazardous areas are revealed, and displacements of the growing dump are predicted. The developed model enables operational forecasting of strength loss at dumps.

Based on the analysis of qualitative interaction between rocks and a rock-breaking tool, a new coefficient of the tool efficiency is proposed. This coefficient makes it possible to estimate the quality of the tool impact on broken rocks and to predict energy input of rock breaking and, consequently, productivity of mining machines in specific geotechnical conditions.

The authors analyze numerically growth of a cross fracture between two existing fractures under multiple directional hydrofracturing using chemically active mixtures. The scope of the studies embraces effect exerted by problem parameters, such as value and orientation of external compression field, rate of healing of fractures, size and intermediate spacing of fractures, on deviation of a fracture from its initial orientation. The results are meant for optimization of the local hydrofracturing method for steam-distribution and producing wells in low-gravity oil reservoirs.

Under analysis is electrohydraulic crushing of rocks under electric charge using nanosecond high-stress pulses to optimize ore pretreatment. A nanosecond high-voltage generator of pulses at a capacity to 500 MW is designed and tested. A flow-through discharge cell at a voltage to 550 kW is developed. The new method of mineral crushing is highly efficient and enables designing commercial plants for electrohydraulic rock processing.