scholarly journals http://www.mining-science.ru/download/2020/3/04.pdf

2020 ◽  
pp. 31-38
Author(s):  
Nikolai Cherdantsev ◽  
Keyword(s):  
Rock Mass ◽  
Elasticity Theory ◽  
Granular Media ◽  
Limit State ◽  
Coal Pillar ◽  
Elastoplastic Problem ◽  
Coal Bed ◽  
Problem Solution ◽  
Geomechanical State ◽  
Exterior Boundary Value Problem

Introduction. Reliable forecasts of pillars geomechanical state are required to ensure rhythmic and safe work when mining a coal bed. Research aim is to construct a state model of the coal pillar located between the headways, based on the fundamental methods of elasticity theory and mechanics of a granular media, carry out a computational experiment within the model, and analyse the results. Methodology. The stress field in the coal pillar has been constructed in the course of solving the elastoplastic problem. By replacing the ultimately stressed marginal zone of the bed with the stresses which act within the zone, the problem has been reduced to the second exterior boundary value problem of elasticity theory and has been solved by the boundary element method. Ordinary and special Coulomb–Mohr criteria simultaneously fulfilled for the coal bed and rock mass contact are the criterion of the limit state onset. Actual pillar load is determined by integrating the vertical stress curve along the bed roof, which has been obtained from elastoplastic problem solution, while the ultimate load is determined from the condition that the whole pillar is in ultimately stressed state. Results. The dependence between the safety factor of the pillar between two identical headways, determined by V. D. Shevyakov method, and the growth of its width represents a graph in the form of a monotonically increasing curve. The curve flattens as soon as the depth increases. Summary. The results from the developed model of coal rock mass geomechanical state can be successfully used as coal pillar strength forecasts.

scholarly journals The effects of dynamic pressure on the stability of prepared drifts near the working surface areas

2021 ◽  
Vol 62 (1) ◽  
pp. 85-92
Author(s):  
Nhan Thi Pham ◽  
Nghia Viet Nguyen ◽  
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
Dynamic Pressure ◽  
Coal Pillar ◽  
Side Wall ◽  
Stability Loss ◽  
Surface Areas ◽  
Working Face ◽  
Deformation Stress ◽  
The Right

Due to the effects of dynamic pressure, the stress distribution of rock mass is very complex. The reason for this could be a risk of stability loss for an auxiliary tunnel system constructed within the study area. In this article by using Flac3D software the author simulated two adjacent working faces with the thickness of 5 m natural coal pillar. Three factors: the upper working face excavation process, auxiliary tunnel mining process, and the location of lower working face, affected by deformation, stress distribution, safety of lower floor area and surrounding rock mass of tunnel. The research results show that during the excavation, the mechanical behavior of the rock mass surrounding the auxiliary tunnel showed displacements, volatility, and phase characteristic. The displacement on the auxiliary tunnel boundary in both excavation and working face cases showed that the roof and the left side wall displacement was greater than the right side wall and the bottom. Therefore, the distance between the auxiliary tunnel and the empty mining space needs to be computed to meet technical and economic requirements.

scholarly journals A physical model study of surrounding rock failure near a fault under the influence of footwall coal mining

2020 ◽  
Author(s):  
Shukun Zhang ◽  
Lu Lu ◽  
Ziming Wang ◽  
Shuda Wang
Keyword(s):  
Rock Mass ◽  
Physical Model ◽  
Hanging Wall ◽  
Coal Pillar ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Pillar Width ◽  
Model Study ◽  
Working Face ◽  
Coal Pillars

AbstractA study of the deformation of the surrounding rock and coal pillars near a fault under the influence of mining is conducted on a physical model for the design of coal pillars to support and maintain the roofs of adjacent fault roadways. This research is based on the 15101 mining face in the Baiyangling Coal Mine, Shanxi, China, and uses simulation tests similar to digital speckle test technology to analyse the displacement, strain and vertical stress fields of surrounding rocks near faults to determine the influence of the coal pillar width. The results are as follows. The surrounding rock of the roadway roof fails to form a balance hinge for the massive rock mass. The vertical displacement, vertical strain and other deformation of the surrounding rock near the fault increase steeply as the coal pillar width decreases. The steep increase in deformation corresponds to a coal pillar width of 10 m. When the coal pillar width is 7.5 m, the pressure on the surrounding rock near the footwall of the fault suddenly increases, while the pressure on the hanging wall near the fault increases by only 0.35 MPa. The stress of the rock mass of the hanging wall is not completely shielded by the fault, and part of the load disturbance is still transmitted to the hanging wall via friction. The width of the fault coal pillars at the 15101 working face is determined to be 7.5 m, and the monitoring data verify the rationality of the fault coal pillars.

CALCULATION OF THE GEOMECHANICAL STATE OF MINE WORKING SUPPORT AND SURROUNDING ROCK MASS IN CONDITIONS OF MINING ORE DEPOSITS IN EAST KAZAKHSTAN

2020 ◽  
Vol 2 ◽  
pp. 89-97
Author(s):  
Andrey A. Krasnovsky ◽  
Viktor M. Seryakov ◽  
Yuri N. Shaposhnik ◽  
Denisi A. Shokarev
Keyword(s):  
Rock Mass ◽  
Mine Working ◽  
Strain State ◽  
Ore Deposits ◽  
Surrounding Rock ◽  
Stress Fields ◽  
Uniform Pressure ◽  
Stress Strain ◽  
East Kazakhstan ◽  
Geomechanical State

The statement of the problem of determining the stress-strain state of support and rock mass around the mine working in unstable rocks, in case of voids filling with phenol resins is proposed. The initial parameters used in the calculations correspond to the conditions of mining ore deposits in East Kazakhstan. The distribution character of stress fields in the support and their change depending on geometric sizes of the area filled with phenol resins is determined. It is shown that using phenol resins causes formation of a uniform pressure of surrounding rocks on the arch part of the support and facilitates an increase in its stability.

Analysis of the Trajectory of a Hydraulic Fracture near the Seam Working and the Conditions for its Straight-line Growth

2021 ◽  
pp. 18-23
Author(s):  
N.V. Cherdantsev ◽  
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Hydraulic Fracture ◽  
Boundary Value ◽  
Elastoplastic Problem ◽  
External Boundary ◽  
General Criterion ◽  
Relative Pressure ◽  
Limiting State ◽  
Straight Line

Model of the geomechanical state of a disc hydraulic fracture propagating in the solid rocks near the seam working is based on the methods of solid mechanics and fracture mechanics. Stress field in the coal-rock mass containing in-seam working and growing hydraulic fracture was constructed as a result of solving an elastoplastic problem, in which the area of plasticity is the extremely stressed zones of the edge parts of the seam. The stress field in the edge parts was determined in the course of the numerical solution of three boundary value problems of the seam limiting state. The criteria for the onset of the limiting state are the general criterion of the Coulomb — Mohr limiting state for the formation and a special criterion for the limiting state for its contact with the rock mass. By replacing the extremely stressed zones with the stresses acting on their contact with the rock mass, the elastoplastic problem is reduced to the second external boundary value problem of the theory of elasticity, which is solved by the method of boundary integral equations. At the relatively low fluid pressures in the pumping unit, the trajectory of the hydraulic fracture is a smooth curved line of the small length with a significant deviation of its ends from the direction of the seed crack. With increasing fluid pressure, the crack length increases, and the deviation from the direction of the seed crack decreases. There are fluid pressures at which the crack propagates in a straight line and practically does not change its original direction. The straight-line trajectory of the crack in the vicinity of the working located at different depths corresponds to a point on the graph of the dependence of the relative length of the crack on the fluid relative pressure. This graph is a straight line.

Evaluation of the geomechanical state of a rock mass in working deposits in a cryolithozone

1993 ◽  
Vol 29 (3) ◽  
pp. 217-220
Author(s):  
V. Yu. Izakson ◽  
V. G. Grinev ◽  
A. V. Samokhin ◽  
G. P. Neobutov ◽  
S. P. Shkulev
Keyword(s):  
Rock Mass ◽  
Geomechanical State

Study of the Three-Dimensional Global Limit Equilibrium Method Applied to the Stability of Rock Slope

2012 ◽  
Vol 249-250 ◽  
pp. 1099-1102
Author(s):  
Yi Sheng Huang ◽  
Jian Lin Li
Keyword(s):  
Rock Mass ◽  
Stability Analysis ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Limit State ◽  
Three Dimensional ◽  
Limit Equilibrium Method ◽  
Equilibrium Method ◽  
The Stability ◽  
Loose Rock

Amending the normal stress over the slip surface based on the stress field by numerical analysis, applying the three-dimensional global limit equilibrium method to the stability analysis of tension-slackened rock mass in the right bank of Yagen hydropower station. Stability analysis shows that if do not take any measures, the loose rock mass stability can cater to the Specification demand, but some small sliders is in the limit state under the water and earthquake condition, if use the cutting slope and unloading scheme, the whole loose rock mass and the all small sliders can meet the Specification standard stability requirements.

scholarly journals Linear solver performance in elastoplastic problem solution on GPU cluster

2017 ◽  
Author(s):  
Yu. V. Khalevitsky ◽  
A. V. Konovalov ◽  
N. V. Burmasheva ◽  
A. S. Partin
Keyword(s):  
Elastoplastic Problem ◽  
Problem Solution ◽  
Gpu Cluster ◽  
Linear Solver ◽  
Solver Performance
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