Change in stress-strain behavior of coal-rock mass during coal mining

A rock mass is composed of blocks, and the interfaces of various scale blocks represent different kind discontinuities. Such structure is also associated with nonuniformity of stresses. The stress–strain behavior of rock mass in the Khibiny apatite–nepheline massif in the course of mining is governed by natural geological and induced faulting. This study considers modification of the finite element method in the stress–strain analysis of rocks with regard to deformation at interfaces of different-modulus media. After 2D tests of interface elements, an optimal type of the interface element was selected for the 3D modification implementation. The latter can improve reliability of geomechanical forecasts in mineral mining in complicated geological and geodynamic conditions. From the test data on modification of interface elements, the optimal interface element is assumed to be the six-node interface element proposed by V. Kalyakin and Jianchao Li. The six-node interface element is introduced in the model of a tunnel with simulation of an unloading line at the boundary. The adequate results on adjacent rock deformation are obtained. The 3D interface element modification reveals its peculiarities and limitations as regards introduction in finite element models of mineral deposits and enclosing rock mass. The ways of solving these problems are proposed.

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STUDY OF REGULARITIES OF CHANGES IN STRESS-STRAIN STATE OF COAL ROCK MASS IN FRACTURED ZONES

Фундаментальные и прикладные вопросы горных наук ◽

10.15372/fpvgn2019060116 ◽

2019 ◽

Vol 6 (1) ◽

Keyword(s):

Rock Mass ◽

Strain State ◽

Stress Strain ◽

Stress Strain State ◽

Fractured Zones ◽

Coal Rock

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The model of a stress-strain state of the coal-rock mass in the development of the coal seam

MINING INFORMATIONAL AND ANALYTICAL BULLETIN ◽

10.25018/0236-1493-2019-1-1-3-10 ◽

2019 ◽

Vol 1 (1) ◽

pp. 3-10

Author(s):

I.A. Turbor ◽

◽

D.N. Shurygin ◽

Keyword(s):

Rock Mass ◽

Coal Seam ◽

Strain State ◽

Stress Strain ◽

Stress Strain State ◽

Coal Rock

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STRESS-STRAIN BEHAVIOR OF ROCK MASS AROUND CYLINDRICAL EXCAVATIONS WITH THE PRESET CAUCHY STRESS STRESSES AND DISPLACEMENTS AT THE BOUNDARIES

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2021-2-4-158-163 ◽

2021 ◽

Vol 2 (4) ◽

pp. 158-163

Author(s):

Anvar I. Chanyshev ◽

Igizar M. Abdulin

Keyword(s):

Rock Mass ◽

Symmetry Axis ◽

Strain Analysis ◽

Polar Angle ◽

Surrounding Rock ◽

Rotation Vector ◽

Cauchy Stress ◽

Stress Strain ◽

Strain Behavior

The authors solve the problem on the stresses and strains of rock mass around a cylindrical excavation with the preset vectors of the Cauchy stresses and displacements at the boundary. It is assumed that the surrounding rock mass is elastic. Along the cylindrical excavation (free of stresses), displacements are measured as functions of two surface coordinates (polar angle and length along the symmetry axis of the excavation). These measurements are used to determine all components of tensors of stresses and strains at the boundary, and all coordinates of rotation vector. It is shown how this information can be used in the stress-strain analysis of rock mass farther from the excavation.

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Assessment of influence of short-period geodynamic movements on stress-strain behavior of rock mass

MINING INFORMATIONAL AND ANALYTICAL BULLETIN ◽

10.25018/0236-1493-2020-31-0-90-104 ◽

2020 ◽

pp. 90-104

Author(s):

Yu. P. Konovalova ◽

V. I. Ruchkin

Keyword(s):

Rock Mass ◽

Strain Tensor ◽

Space Distribution ◽

Cycle Duration ◽

Stress Strain ◽

Strain Behavior ◽

Principal Axes ◽

Short Period ◽

Check Points ◽

Cyclic Movement

Geodynamic diagnostics of rock mass is critical in terms of safe arrangement and operation of subsoil use objects. The modern geodynamic movements are one of the factors that govern the stress-strain behavior of rocks. The experimental research accomplished in the recent decades show that geodynamic movements are the wide-spread phenomena of complex time-and-space distribution. It is conditionally assumed to distinguish between the trend movements of the same direction and velocity over the period of observations and the cyclic short-period movements with cycle duration from a few minutes to a few hours. The cyclic short-period geodynamic movements can exert direct or indirect impact on subsoil use objects. The cyclic nature is governed by many natural factors. The influence of one or another factor on the stress-strain behavior of rock mass is yet unstudied unambiguously to date. However, it is evident that strains governed by the cyclicity of movements should be taken into account in geodynamic diagnostics. The implemented studies of short-period movements on testing grounds by continuous monitoring using GNSS methods for many hours at spacing from two hundred meters to two kilometers revealed that directions of displacement of check points frequently exceeded accuracy of their determination. During the experiments, a procedure was developed to determine parameters of strain tensor in rock mass based on the prevailing direction and amplitude of short-period movements. The amplitude of short-period movement is a difference between the minimal and maximal values of displacements in a set of discrete measurements within continuous observation session. The obtained field of strains was compared with the values calculated by the data on the trend geodynamic movements for 6 years with the same check points in the same pattern. The correlation is found between the orientations of principal axes of strain tensors calculated by the data on the trend and shortperiod movements. The developed procedure makes it possible to take into account the shortperiod cyclicity of the modern geodynamic movements, and the found correlation between the orientation of strain tensor of the trend and cyclic movement enable express estimation of changes in the stress-strain behavior of rocks.

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