M. V. Kurlenya

Problems of nonlinear geomechanics. Part 1

In the study, an attempt is made to present the most important results of experimental researches on nonlinear geomechanics—a rapidly developing scientific trend in recent years—from single positions within the framework of Academician M. A. Sadovskys concept relative to the block-hierarchical structure of rock masses. The key role of the linear embedment coefficient of geoblocks for contiguous hierarchical levels, and the statistical characteristic of the average distances between the edges of cracks separating the structural blocks between themselves to the diameters of these blocks, as well as the scale factor of the phenomenon of the zonal disintegration of rocks around underground workings is demonstrated in the development of nonlinear geomechanical processes at various hicrarchical levels: from monatomic-crystalline to planetary scale. A number of major scientific problems, a solution of which demands particular attention of experimenters and theoreticians is formulated. The circle of problems touched upon in this part of the article concerns primarily the analysis of nonlinear quasi-static processes.

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

Conclusions1. 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 (μ-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 μ-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 μ-waves under certain conditions of energy actions can leads to the occurrence of the effect of anomalously low friction between interacting blocks (carriers of μ-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).

Geomechanical conditions for quasi-resonances in geomaterials and block media

ConclusionsBased on voluminous information about relations between the dimensions of the central zones of crustal earthquakes and various energy classes of underground explosions, as well as mine shocks and man-induced tremors, therefore, the hypothesis that we had previously advanced relative to the quasi-resonant mechanism of their manifestation is confirmed. Here, the geomechanical conditions for the development of quasi-resonances associated with the inducement of pendulum waves are characterized by the dimensionless energy criterion k:

Sealing of coal bed methane drainage holes by barrier screening method

k = \frac{W}{{M V_{sp}^2 }} = (1 \div 4) \cdot 10^{ - 9} ,

Experimental and analytical method for assessing stability of stopes

where W is the seismic energy released from the central zone of dynamic manifestations of mine pressure (earthquakes, mine shocks, etc.), or the total energy U0 of the central zone, multiplied by the seismic-effect factor of explosions with a corresponding total energy, M is the mass of the rock in the central zone, and Vsp is the spread velocity of longitudinal waves in the geoblocks. Manifestation of the effect of anomalously low friction in the geoblocks plays a major role when the quasiresonant mechanism of mine pressure or explosions is realized.The study was performed with financial support from the Russian Fund for Fundamental Research (Grant No. 96-05-66052).

Froth gel for gas-bearing coal bed hydrofracturing in mine conditions

The authors offer an approach to estimating deformation of rock mass around a stope (zonal disintegration) at deep levels. The algorithm of geomechanical condition of rocks is developed, and the ranges of stresses and strains in the zone of influence of a stope are identified.

Longitudinal multichannel optoelectronic deformometer

The authors have developed the barrier screening method to seal coal bed methane drainage holes. The method reduces air leakage from enclosing rocks to evacuation holes. The compositions of screens with external seal preventing from fluid leakage to ambient medium are offered and analyzed.

Mathematical modeling of stress state of surrounding rocks around the well subjected to shearing and normal load in hydraulic fracturing zone

The article presents guidelines, test model design and barrier shield design model aimed to improve the quality of sealing coal bed methane drainage holes by the barrier shielding method.