L. A. Nazarov

Evolution of stress fields and induced seismicity in operating mines

The authors propose a new procedure for establishment of the space-time relationships between the quantity and energies of seismic events and the stress-strain state parameters using deterministic information on variation of geomechanical fields and the statistical analysis of the induced seismicity data. The new procedure has been verified under conditions of Tashtagol iron ore mine.

Genesis and evolution of discontinuities in geomaterials: Theory and a laboratory experiment

The authors designed and manufactured a test stand to study origination and evolution of discontinuities in rocks. Based on the laboratory experimental data obtained for artificial geomaterials and the new-developed geomechanical model, the state equation for shear deformation of a discontinuity is synthesized.

Reconstruction of 3D stress field in coal–rock mass by solving inverse problem using tomography data

The theoretically evaluated multi-disciplinary approach enables determination of stress state of a coal–rock mass in the area of coal cutting using a package of geomechanical and geophysical information. The approach is based on successive solutions of two inverse problems in the framework of a geomechanical model: coal-bed tomography and assessment of horizontal components of external stress field. The numerical experiments demonstrate resolvability of the inverse problems given appropriate monitoring system ensures sufficient seismic coverage of a coal-bed in the domain of steep spatial gradients of elastic waves and the presence of regular composition in the frequency range of the order of hundreds of hertz in the sounding signal generated by a cutter–loader and/or other coal-face work machinery.

Evolution of geomechanical and electro-hydrodynamic fields in deep well drilling in rocks

The authors have developed and numerically implemented 3D model of evolution of geomechanical and hydrodynamic fields during deep well drilling. The modeling exercises showed low-permeable zones of irreversible deformations that appear under definitely interrelated rock strength properties, drilling mud pressure and in situ horizontal stresses in the borehole environment. These low-permeable irreversible-deformation zones give rise to angular anisotropy of distribution of water content and drilling mud resistivity in the invaded zone, which greatly affects geophysical logging data and must be taken into account in the logging data inversion.

Three-dimensional geomechanical model of the Tashtagol iron-ore deposit

ConclusionThe diverse information collected during fulfillment of the present study on the Tashtagol deposit as a geomechanical entity on the local level, and also the procedure developed for numerical modeling make it possible to perform a detailed analysis of the geomechanical situation that develops near mining operations and in the adjacent mass. The constructed model is “open” for the introduction of additional information on stress fields, the number, location, and state of faults, and other geomechanical information, and is also easily adapted for solution of dynamic (for example, on blast-induced breaking) problems. Similar models may be constructed for all iron-ore deposits of the Gornoi Shorii.The authors express appreciation to A. A. Eremenko, O. V. Kuchai, V. F. Khramtsov, and V. A. Shalaurov for data and information that they submitted on the structure and stress-state of the Tashtagol deposit.The study was performed with financial support of the Russian Fund for Fundamental Research (Grant No. 95-05-15604).

Evolution of thermohydrodynamic fields at tailings dam at Kumtor mine (Kyrgyz Republic)

The authors have developed the FEM geomechanical model to describe evolution of temperature and hydrodynamic fields at the tailings dam of the Kumtor Gold Mine, Kyrgyzstan, in the permafrost region. The influence exerted by the temperature variation in the liquid waste accumulated in tailings pond and by the changes of size of impervious screen on the volume of filtrate material through the dam is evaluated in numerical experiments. It is shown that the pressure variation rate in the observation hole can be the indicator of the impervious screen rupture.

Estimation of state and properties of various-scale geomechanical objects using solutions of inverse problems

The authors comment on features of formulation and structure of input data for the inverse problems used in rock mechanics to estimate state and properties of natural and anthropogenic objects at various spatial scales. The article gives examples of using solutions of inverse problems in coal bed degassing monitoring, based on data on changes of pressure in hydraulic props in the overlying bed, and in assessment of deformation parameters of inclusions, based on data of uniaxial compression tests of artificial heterogeneous specimens.

Evolution of stresses and permeability of fractured-and-porous rock mass around a production well

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 deformation 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.

Acoustic method for defining the stress state of a rock massif based on solution of the seismic inverse problem

A method for estimating the stress–strain state of a rock massif in the vicinity of underground facilities is substantiated. This method is based on solution of the boundary inverse problem of defining the components of an external stress field from the acoustic sounding data. The acoustic sounding data used are the arrival times of diving head longitudinal waves, recorded in a long mine shaft. Numerical experiments have revealed the optimal arrangement of the recording network and the limited relative error in the input data, which, taken together, provide for solvability of the inverse problem.

Estimation of depth and dimension of underground void in soil by subsidence trough configuration based on inverse problem solution

The authors offer an approach to estimating parameters of underground voids formed in soil under natural or induced forces. Irreversible deformation of soil is modeled using discrete element method. The formulated inverse problem on geometry and occurrence depth of a void by the data on configuration of the subsidence trough has a single-valued solution.