scholarly journals Analysis of Stress-Strain States in the Vicinity of Mining Excavations in a Rock Mass with Variable Mechanical Properties

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5567
Author(s):  
Marek Jendryś ◽  
Stanisław Duży ◽  
Grzegorz Dyduch
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Numerical Simulations ◽  
Mechanical Parameters ◽  
Mining Operations ◽  
Axial Forces ◽  
Internal Forces ◽  
Random Variability ◽  
The Stability ◽  
The Impact

Rock mass is a medium created through processes that have lasted over four billion years, and its intrinsic feature is the variability of the parameters that describe it. A particularly high variability of mechanical parameters is observed in Carboniferous sedimentary and metamorphic rocks. The mechanical properties, especially the rock mass strength, are essential for the design and maintenance of the stability of excavations conducted in it and for the safe conduct of mining operations. This article presents the test results confirming the random variability of the mechanical parameters of the rock mass. The second part of the article presents the results of numerical simulations mapping the Carboniferous rock mass along with a 1000 m deep tunnel excavation protected by steel arch supports. Numerical simulations were carried out for models with different variability coefficients of strength and deformation parameters, and the obtained results were analyzed in terms of damage zones and rock mass stress state as well as axial forces in the modelled supports. The results of the simulation demonstrate the impact of the variability of rock mass properties on its state in the vicinity of the excavation and, consequently, on the internal forces in the steel supports and their uneven loading along the length of the excavation. This fact should be taken into account in their design.

scholarly journals The Use of the Collocation Algorithm for Estimating the Deformations of Soil-Shell Objects Made of Corrugated Sheets

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Czesław Machelski
Keyword(s):  
Strain Gauges ◽  
Boundary Constraints ◽  
Axial Forces ◽  
Collocation Points ◽  
Geodetic Measurements ◽  
Significant Divergence ◽  
Internal Forces ◽  
Support Conditions ◽  
Static Conditions ◽  
The Impact

AbstractThe algorithm presented in this paper is intended for the analysis of deformations of shells in the construction phase of soil-shell objects when strain gauges and geodetic measurements are used. During the construction of such an object, large displacement values occur and the impact of axial forces on the displacement of a corrugated metal sheet is small. Internal forces (strain gauges), as well as the displacements of a selected circumferential band of the shell are determined directly from such observations.The paper presents two examples of the analysis of large span shell structures of constructed objects, as well as the assessment of the effectiveness of the finite difference method (FDM) in beam schemes. Good deformation mapping was indicated using the collocation algorithm and the differential approach to the solution when there is a dense mesh and regular distribution of measuring points. In the analysed examples, a significant divergence between the support conditions adopted in the FEM calculation models and the actual static conditions in the objects was indicated. The collocation algorithm is especially designed for such situations. Collocation points in such a solution are used to consider a beam – separated from a structure and without boundary constraints, but with specific changes in curvature – as a reference system, which is determined from the geodetic measurements of two collocation points.

Rock Movement in Tectonic Zones. Mining Activities and Rock Pressure Management in the Norilsk-Kharaelakh Fault Area

2020 ◽  
pp. 148-151
Author(s):  
S.G. Kirillov ◽  
Z.G. Ufatova ◽  
I.F. Khrushchev ◽  
K.A. Bashirov
Keyword(s):  
Rock Mass ◽  
High Mobility ◽  
Mining Operations ◽  
Profile Line ◽  
Initial Stage ◽  
Tectonic Zones ◽  
Rock Movement ◽  
Hazard Level ◽  
And Control ◽  
The Impact

The article describes the rock mass state within the boundaries of the Skalistiy mining allotment. The ore mass within the mine field was found to preserve its rock-bump hazard and show high mobility in the impact zone of the Norilsk-Kharaelakh Fault and the associated high failure potential manifested as roof cavings. Based on the monitoring results along underground profile lines, it was concluded that the displacement process is currently at its initial stage. Moreover, the maximum subsidence in the central part of the profile line is about 3 times higher (up to 35 mm) than in other areas. This is caused by immediate proximity of this zone to the Norilsk-Kharaelakh Fault. Assessment of the bump hazard level of this rock mass with the help of the Prognoz-2 instrument that was performed by the rock-bump forecasting and control teams of the mine and the Norilskshakhtstroy company, showed the 'Not Hazardous' category in all cases. However, the progress of mining operations towards the Norilsk-Kharaelakh Fault may lead to deterioration in the condition of mine workings. This can be manifested through rock exfoliation from the walls of the advance workings of the safety layer in highly and extremely faulted rocks. In addition, permanent workings, which are one of the most critical structures of the production level and which will be used until the development of the deposit area adjacent to the Norilsk-Kharaelakh Fault is completed, will be maintained in increasingly difficult conditions. The article describes recommendations for mining operations in the fault area with account for the current mining and geomechanical situation and the potential for its change.

Stability Analysis about the Impact of Soft Rock to the Underground Cavern Group

2013 ◽  
Vol 706-708 ◽  
pp. 560-564
Author(s):  
Yi Huan Zhu ◽  
Guo Jian Shao ◽  
Zhi Gao Dong
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Stability Analysis ◽  
Soft Rock ◽  
Element Model ◽  
Underground Excavation ◽  
Power Station ◽  
Excavation Process ◽  
The Stability ◽  
The Impact

Soft rock is frequently encountered in underground excavation process. It is difficult to excavate and support in soft rock mass which has low strength, large deformation and needs much time to be out of shape but little time to be self-stabilized. Based on a large underground power station, finite element model analysis was carried out to simulate the excavation process and the results of displacement, stress and plasticity area were compared between supported and unsupported conditions to evaluate the stability of the rock mass.

scholarly journals Reverse Analysis for Determining the Mechanical Properties of Zeolite Ferrierite Crystal

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
J. Lin ◽  
X. Y. Niu ◽  
X. F. Shu
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Single Crystal ◽  
Numerical Simulations ◽  
Work Hardening ◽  
Mechanical Parameters ◽  
Stress Strain Relation ◽  
Work Hardening Rate ◽  
Nanoindentation Experiment ◽  
Reverse Analysis

In order to explore more mechanical properties of zeolite Ferrierite (FER) single crystal, a method of determining its mechanical properties—nanoindentation reverse analysis—was obtained based on the nanoindentation experiment and numerical simulations, and this will be presented in this paper. The yield stress and the characteristic work-hardening rate were gained if its stress-strain relation was a bilinear constitutive relation. The mechanical parameters obtained by reverse analysis have been compared with ones gained by nanoindentation finite-element numerical simulations.

scholarly journals Analysis of Possible Origination of Domes in Longwalls

2019 ◽  
Vol 4 (1) ◽  
pp. 57-64
Author(s):  
R. I. Imranov ◽  
E. N. Khmyrova ◽  
O. G. Besimbayeva ◽  
S. P. Olenyuk ◽  
A. Z. Kapasova
Keyword(s):  
Rock Mass ◽  
Factor Of Safety ◽  
Coal Seams ◽  
Mining Operations ◽  
Compressive Stresses ◽  
Digital Modeling ◽  
Geological Conditions ◽  
The Stability ◽  
High Ash Coal ◽  
Borehole Log

The research is aimed at solving problems of assessing underground working stability in complicated mining and geological conditions to increase reliability and safety of mining operations. Analysis of geomechanical processes occurring in a rock mass during extraction of coal seams to determine the stability of mining block roof is the most important task. The performed digital modeling of the rock mass based on the structural logs for K1 seam and the nearest borehole log enabled highly detailed identifying the types of rocks occurred in the seam roof and their strength characteristics, compressive stresses. To determine the stability of a mining block roof, the factor of safety of the rocks was used, which was determined by modeling method using Phase 28.0 and Rockscince software. The carbonaceous argillite parting 0.09–0.12 m thick was taken as the contact of the longwall with the seam roof, and, for completeness of the analysis, the upper high-ash coal member in the seam roof up to 0.7 m thick was used. The modeling findings, presented in the graph of dependence between the safety factor and the distance between the belt heading and air drift, showed that the probability of dome formation in the longwall is high, as the factor of safety of the rocks is less than unity, that indicates the roof instability in the course of the coal seam block extraction. The modeling methods allowed assessing the mine working stability, based on which the measures to improve the reliability and safety of mining operations can be timely developed, and due technical and technological solutions shall be reached.

scholarly journals Physical and mechanical properties of the rocks of the Starobinsky deposit forming the Third potash layer and its roof

2021 ◽  
Vol 65 (4) ◽  
pp. 484-494
Author(s):  
A. B. Petrovsky ◽  
V. Ya. Prushak ◽  
E. A. Lutovich
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Geological Structure ◽  
Mining Operations ◽  
The Third ◽  
Composition And Structure ◽  
Mining Conditions ◽  
The Stability ◽  
Roof Falling ◽  
Main Factor

The geological structure and the physical-mechanical properties of rocks composing and overlapping the Third potash formation in the areas of the mine field mine No. 4 JSC Belaruskali, which are scheduled to practice, are studied. The geological sections of the Third potash layer and its roof were built, the thickness of sylvinite and halite layers was measured, the roof falling of the rocks of the layer with a height of up to 20 m was assessed, and the type of immediate roof was determined by the composition and structure of its constituent rocks. It was established that the strength under uniaxial compression of both sylvinite and halite layers for the areas under consideration differs slightly. Therefore, to solve engineering problems of ensuring the stability of mine workings and to calculate fastening parameters, strength values averaged over the groups of layers can be used that correlate well with the percentage of weak and clay interlayers. The same applies to Poisson’s ratio, the values of which for various layers of formation are slightly different and can be taken by their averaging. It is shown that the main factor that negatively affects the strength of rocks occurring in the roof of the Third potash seam is the presence of weak and clay interlayers, which increases with depth. The introduction of the obtained results allows us to improve the calculation accuracy of securing mining parameters, to reduce the costs of their maintenance, and to improve the safety of mining operations in developing the Third potash formation in complex geological and mining conditions.

Effect of Fly Ash Content on Mechanical Properties of Cement-Fly Ash Stabilized Crushed Stones

2014 ◽  
Vol 548-549 ◽  
pp. 228-232 ◽  
Author(s):  
Xiao Chen ◽  
Ji Wei Liu ◽  
Ming Kai Zhou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Crack Resistance ◽  
Unconfined Compressive Strength ◽  
Resilient Modulus ◽  
Ash Content ◽  
Mechanical Parameters ◽  
Cleavage Strength ◽  
The Impact

To improve the impact of fly ash on the properties of cement-fly ash stabilized crushed stone, and promote it popularize and apply better. This paper investigated the effect of fly ash content on unconfined compressive strength, cleavage strength and resilient modulus of cement-fly ash stabilized crushed stones, and those relationships between mechanical parameters. The results showed that with increasing of the fly ash content, the unconfined compressive strength and cleavage strength increased at first, then decreased, the resilient modulus decreased, and The brittleness index increased. We can conclude that the optimal fly ash content is between 10% and 15%, and increment of fly ash content can improve its crack-resistance.

INFLUENCE OF MOISTURE ON MECHANICAL PROPERTIES OF CELLULOSE INSULATION PAPER

2014 ◽  
Vol 28 (07) ◽  
pp. 1450051 ◽  
Author(s):  
Y. Y. WANG ◽  
M. TIAN ◽  
H. X. XU ◽  
P. FAN
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bond ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Tensile Tests ◽  
Appreciable Effect ◽  
Mechanical Parameters ◽  
Amorphous Cellulose ◽  
Hydrogen Bond Networks ◽  
The Impact

This paper aims to investigate the impact of moisture on mechanical properties of insulation paper. According to the molecular modeling approach proposed by Theodorou, the amorphous cellulose models of insulation paper with different moisture contents were built up to calculate mechanical parameters and hydrogen bond networks. And relevant conclusions could be drawn through further analysis on these calculation results: water molecules can destroy hydrogen bond network between the neighboring cellulose molecules, which might be responsible for the significant decrease of Young's modulus and other mechanical parameters, while no appreciable effect of intramolecular hydrogen bonds on mechanical properties was detected. Thus tensile tests were also carried out to study the moisture influence on the Young's modulus, by which the result of the simulation was approved.

scholarly journals ASSESSMENT OF THE IMPACT OF GEOMECHANICAL PARAMETERS VARIABILITY ON UNDERGROUND EXCAVATIONS STABILITY USING RESPONSE SURFACE METHOD

2013 ◽  
Vol 35 (1) ◽  
pp. 183-194 ◽  
Author(s):  
Witold Pytel ◽  
Joanna Świtoń
Keyword(s):  
Rock Mass ◽  
Response Surface ◽  
Response Surface Method ◽  
Safety Issue ◽  
Mineral Deposit ◽  
Mining Operations ◽  
Mean Values ◽  
Surface Method ◽  
Geomechanical Parameters ◽  
The Impact

Abstract Recognition of properties of the rock mass surrounding a mineral deposit is particularly important for the mining operations at greater depths. Since the rock mass is usually not homogeneous, and its parameters have characteristics of randomness, underground workings safety issue should always be analysed taking into account the dispersion of the values of these parameters around their mean values. In order to assess the impact of geotechnical parameters uncertainty on the excavation stability one uses the appropriate statistical approach. In this paper, by analysing successive combinations of geomechanical parameters of the rock in the measured range, we examined the effect of their variability on risk of underground excavation instability using response surface method.

Study about Mechanic Parameter of Slope Rock Mass' Structure Plane

2013 ◽  
Vol 368-370 ◽  
pp. 1551-1555
Author(s):  
Si Yu Wu ◽  
Bo Huang ◽  
Rui Jun Liu
Keyword(s):  
Rock Mass ◽  
Deformation Modulus ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Test Results ◽  
Rock Mass Structure ◽  
Stability Of Slope ◽  
Slope Rock ◽  
The Stability ◽  
Structure Plane

Firstly, the stability of the slope need to determine mechanical parameters of slope rock mass such as deformation modulus, Poissons ratio, cohesion and internal friction angle, etc. For intact rocks, the mechanical parameters mentioned before are easy to determined. While the stability of slope rock mass is controlled by the deformation and intensity. Therefore, how to determine the mechanical parameters of the structure is the key to analyze the stability of slope rock mass. This paper intends to set the slope rock mass below some extra-large bridge as the research object and use numerical calculation to determine the mechanics parameters of rock mass structure plane on the basis of rock sample mechanics test results.

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