Geomechanical aspects of formation of natural stresses in a concrete mount of a shaft shaft

2020 ◽  
pp. 199-207
Author(s):  
S. V. Sentyabov
Keyword(s):  
Rock Mass ◽  
Analytical Methods ◽  
Structural Parameters ◽  
Strength Properties ◽  
Mine Shaft ◽  
The Earth ◽  
Shaft Lining ◽  
Time Variables ◽  
Average Size ◽  
Structural Blocks

In the presented studies, the laws of the formation of natural stresses in the rock mass are confirmed, which are the sum of gravitational, static tectonic and variable components that have a variable value as a result of uniform periodic volume expansion and contraction of the Earth. The problem of trunk stability is due to the need to solve problems to determine the level of stress-strain state and strength properties in concrete supports. The stress parameters in the lining of the shafts and the monitoring of their changes are determined using a new method for measuring unloading strains. When comparing the stresses obtained experimentally by analytical methods in the concrete support of mine shafts from 2013 to 2019 at experimental test sites in the support having the lengths of bases of 1600 and 70 mm, provided that the number of geoblock ranks at this base is two, a connection with the results of measurements in an array of rocks based on 50 m with an average size of structural blocks of 0.5 m and an investment coefficient of l = 5, which corresponds to three ranks of geoblocks. In practice, it is proposed to use the main identified provisions, namely: the stress state of the mine shaft lining, which is formed as a function of their structural parameters, the full tensor of gravitational tectonic stresses acting in the rock mass at the time of the start of research and time variables, which are determined by natural and analytical methods.

scholarly journals Investigation of stress field parameters at deep horizons of the Gayskoye field**

2020 ◽  
Vol 192 ◽  
pp. 01028
Author(s):  
Sergey Sentyabov ◽  
Albert Zubkov
Keyword(s):  
Rock Mass ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Concrete Lining ◽  
Complex Structures ◽  
Mining Operations ◽  
Volumetric Expansion ◽  
Shaft Lining ◽  
The Stability

The extraction of solid minerals is associated with the penetration of man into the subsoil by creating either relatively simple or extremely complex structures. All mining operations can be safely and efficiently carried out only on the basis of calculating the stability of these structures, which is based on knowledge of the physical and mechanical properties, the stress state of the rock mass and the patterns of their redistribution and formation in mountain structures. The presented studies confirmed the regularities of the formation of natural stresses in the rock mass, which is the sum of gravitational, static tectonic and variable components, which are formed as a result of uniform periodic volumetric expansion and contraction of the Earth. The problem of shaft stability is due to the need to solve problems to determine the level of stress-strain state and strength properties in concrete lining. The parameters of stresses in the shaft lining and monitoring of their changes were determined using the method of measuring unloading deformations. When analyzing the stresses obtained experimentally by analytical means in the concrete lining of mine shafts, a connection was established with the results of measurements in the rock mass on the basis of 50 meters. Based on the experiment, it was confirmed that theoretical and experimental studies prove that a hierarchically blocky massif of magmatic and metamorphic rocks behaves as an elastic and isotropic medium and changes in natural stresses in the massif Δ on the basis of 5-7 ranks of geoblocks, on the contour of the trunk based on 2 –3 ranks of geoblocks and in the concrete lining of mine shafts Δσb obey this law.

scholarly journals Microgravity Survey to Detect Voids and Loosening Zones in the Vicinity of the Mine Shaft

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3021
Author(s):  
Slawomir Porzucek ◽  
Monika Loj
Keyword(s):  
Rock Mass ◽  
Density Distribution ◽  
Geophysical Methods ◽  
Gravity Anomalies ◽  
Vertical Profiles ◽  
Mine Shaft ◽  
Mining Areas ◽  
Shaft Lining ◽  
Under Construction ◽  
Density Zone

In mining and post-mining areas, the assessment of the risks to the surface and its infrastructure from the opening or closed mine is of the utmost importance; particular attention should be paid to mine shafts. The risks include the occurrence of undetected voids or loosening zones in the rock mass. Their detection makes it possible to prevent their impact on a mine shaft and surface infrastructure. Geophysical methods, and in particular, a microgravity method lend themselves for the detection of changes in the distribution of masses (i.e., the density) due to voids and loosening zones. The paper presents the results of surface microgravity surveys in the vicinity of three mine shafts: under construction, working, and a liquidated one. Based on the gravity anomalies, the density distribution of the rock mass for all three cases was recognized. The properties of the anomalies allowed to determine which of the identified decreased density zones may pose a threat to the surface infrastructure or a mine shaft. The microgravity survey made inside the working mining shaft provided information on the density of rocks outside the shaft lining, regardless of the type of lining. No significant decrease of density was found, which means that there are no larger voids outside the shaft lining. Nevertheless, at a depth of 42 m in running sands layer, the decreasing density zone was located, which should be controlled. Additionally, measurements in two vertical profiles gave the possibility of directional tracking of density changes outside shaft lining. Such changes were observed on three boundaries of geological layers, with two of them being on the boundary of gypsum and other rocks.

Mechanism of deformation in rock mass surrounding intersection of mine shaft and salt bed

2021 ◽  
pp. 21-26
Author(s):  
V. P. Marysyuk ◽  
G. V. Sabyanin ◽  
A. A. Andreev ◽  
M. A. Vilner
Keyword(s):  
Rock Mass ◽  
Rock Salt ◽  
Observation Station ◽  
Mine Shaft ◽  
Deformation Stages ◽  
Rock Interface ◽  
Mechanical Linkage ◽  
Shaft Lining ◽  
Materials Used ◽  
Enclosing Rocks

A bed of rock salt in Komsomolsky Mine occurs in sedimentary strata enclosing cage and skip shafts. When water enters rock salt via underground excavations, boreholes and fractures, rock salt can dissolve and wash out, and voids appear in rock mass. Voids at the lining and rock interface should be eliminated so that never re-appear or grow during shaft operation. Materials used to eliminate voids should ensure stable mechanical linkage both with enclosing rocks and lining. Assessment and analysis of geomechanical processes induced by leaching need monitoring of deformations in a shaft. To this effect, one of the simplest and most informative methods is arrangement of an observation station directly in the shaft lining to measure varying distances between check points. The article briefly describes activities aimed to eliminate voids using different composition grouts. From the analysis of monitoring data, the deformation mechanism is described, and the interaction between different deformation stages and grouting steps is determined. The authors appreciate participations of experts M. P. Sergunin, I. A. Shishkina, A. K. Ustinov, V. V. Tsatskin, V. S. Orlov.

scholarly journals Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548 ◽  
Author(s):  
Leonid Agureev ◽  
Valeriy Kostikov ◽  
Zhanna Eremeeva ◽  
Svetlana Savushkina ◽  
Boris Ivanov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Strength Properties ◽  
Alumina Nanoparticles ◽  
Metal Powders ◽  
Wide Range ◽  
The Matrix ◽  
Spark Plasma ◽  
Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

General concept of determining the parameters of non-mining walls of ultra-deep diamond deposits development open pits

2021 ◽  
pp. 48-53
Author(s):  
I. V. Zyryanov ◽  
A. N. Akishev ◽  
I. B. Bokiy ◽  
N. M. Sherstyuk
Keyword(s):  
Rock Mass ◽  
Structural Relaxation ◽  
Slope Angle ◽  
Field Tests ◽  
Friction Angle ◽  
Strength Properties ◽  
Strength Characteristics ◽  
Open Pit ◽  
Open Pit Mining ◽  
Relaxation Coefficient

A specific feature of open pit mining of diamond deposits in Western Yakutia is the construction of the open pits in the zone of negative ambient temperatures, which includes thick permafrost rock mass, and which is at the same time complicated by the influence of cryogenic processes on deformation of pit wall benches. The paper presents the comparative analysis of strength characteristics in frozen and thawed rocks, stability of benches during mining, the general geomechanical approach to the determination of parameters of non-mining walls of the ultra-deep open pit diamond mines, and the parameters of nonmining walls and benches. Optimization of open pit wall configuration should primarily be based on the maximum utilization of the strength properties of frozen rocks in combination with the development of new approaches, calculation schemes and methods for assessing stability of open pit walls and benches of unconventional design, including the non-mining vertical benches. The main design characteristic that determines the parameters of open pit walls is the structural tectonic relaxation coefficient, which specifies the calculated value of cohesion in rock mass. For the diamond deposits, the values of the structural relaxation coefficient were obtained in a series of field tests and back calculations. Full-scale tests were carried out both during exploration operations in underground mines and in open pits. The accuracy of determining the values of the structural relaxation coefficient in the range of 0.085–0.11 is confirmed by the parameters of non-mining walls in an open pit mine 385–640 m deep, with overall slope angles of 38–55° and a steeper H 0.35–0.5 lower part having the slope angle of up to 70° with average strength characteristics of 7.85–11.84 MPa and the internal friction angle of 28.1–37.4°. Using the natural load-bearing capacity of rock mass to the full advantage, which the values of the structural relaxation coefficient of deposits show, allows optimization of open pit wall slope design and minimization of stripping operations.

scholarly journals Physico-Mechanical Performance Evaluation of Large Pore Synthetic Meshes with Different Textile Structures for Hernia Repair Applications

2018 ◽  
Vol 26 (2(128)) ◽  
pp. 79-86 ◽  
Author(s):  
Pengbi Liu ◽  
Hong Shao ◽  
Nanliang Chen ◽  
Nanliang Cheng ◽  
Jinhua Jiang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hernia Repair ◽  
Mechanical Performance ◽  
Structural Parameters ◽  
Strength Properties ◽  
Open Loop ◽  
Burst Strength ◽  
Patch Application ◽  
Large Pore ◽  
Polypropylene Monofilament

This paper studied the relationship between the textile structure of warp knitted hernia repair meshes and their physico-mechanical properties to solve the problem of hernia patch application evaluation and clear the mechanism of hernia patch structure-performance for clinical application. Six different prototypes of large pore meshes were fabricated, including four kinds of meshes with different pore shapes: H (hexagonal), D (diamond), R (round) and P (pentagonal); and two kinds of meshes with inlays: HL (hexagonal with inlays) and DL (diamond with inlays), using the same medical grade polypropylene monofilament. All meshes were designed with the same walewise density and coursewise density. Then the influence of other structural parameters on the physico-mechanical properties of the meshes was analysed. The physico-mechanical properties of these meshes tested meet the requirements of hernia repair, except mesh DL, whose tear resistance strength (12.93 ± 2.44 N in the transverse direction) was not enough. Mesh R and P demonstrated less anisotropy, and they exhibited similar physico-mechanical properties. These four kinds of meshes without inlays demonstrated similar ball burst strength properties, but mesh HL and DL exhibited better ball burst strength than the others. All in all, uniform structures are expected to result in less anisotropy, and meshes with inlays, to some extent, possess higher mechanical properties. And the ratio of open loop number to closed loop number in a repetition of weave of fabric has marked effect on the physico-mechanical properties. Thus we can meet the demands of specific patients and particular repair sites by designing various meshes with appropriate textile structures.

Prediction of the Ground Vibration Rate during Large-scale Explosions in the Underground Conditions

2021 ◽  
pp. 41-45
Author(s):  
V.N. Tyupin ◽  
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Underground Mining ◽  
Calculated Data ◽  
Ground Vibration ◽  
Open Pit ◽  
Vibration Velocity ◽  
Earth Surface ◽  
Seismic Safety ◽  
The Earth

At present, to ensure seismic safety in massive explosions, the analytical dependence of the determination of the vibration velocity of M.A. Sadovsky rock mass is mainly used. This dependence is widely used in the creation of seismic-safe technologies for mineral deposits open-pit and underground mining. However, scientific research and production experience showed that the rate of oscillation depends on the energy parameters of the explosive, the diameter and length of its charges, the number of simultaneously exploded charges, the number of deceleration stages, the deceleration interval, etc. The purpose of this article is to predict the speed fluctuations of the massif on the earth surface when conducting the underground explosions depending on the parameters of large-scale explosions and physical-technical properties of the rock masses in the areas of explosion of the protected object. The formulas for calculating the velocity of rock mass on the earth surface during large-scale explosions in the underground conditions are substantiated and presented. The formulas were used for calculating the vibration velocities of the rock mass on the earth surface in accordance with the parameters of drilling and blasting operations during large-scale explosions in the mines of GK VostGOK. Comparison of theoretical (calculated) data and the results of actual measurements indicates their convergence. By changing the controlled parameters in the calculation formulas, it is possible to quantitatively reduce the seismic effect of a large-scale explosions on the protected objects. Further research will be aimed at studying the influence of tectonic faults, artificial contour crevices, filling massif or mined-out space on the rate of seismic-explosive vibrations during blasting operations in the mines. The research results can be used in the preparation of rules for conducting large-scale explosions at the underground mining.

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