deformation processes
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Author(s):  
V.N. Zakharov ◽  
V.A. Trofimov ◽  
A.V. Shlyapin

Formation of the stress-and-strain state of the rock mass in the roof of mined coal seam depends on the development of the mined-out space. It is believed that the coal seam is located deep enough and it can be assumed that the effect of the daylight surface on its condition can be neglected. In this case, the solution is based on the analytical approach using methods of the complex variable theory and it is reduced to the construction of a single permission analytical function. The paper reviews the evolution of the deformation processes in development of the mined-out space in presence of a hard-to-collapse elastic roof, which is capable of sinking smoothly over time, without sudden caving on the landings on the floor. A particular attention is paid to the phase when the roof and the floor touch each other, i.e. the roof caving, starting from the first touching and up to its complete caving. In this case, two sections of the hanging roof are formed, that are gradually reducing in length as the dimensions of the mined-out space increase. The area of roof caving is progressively increasing, and the vertical compressive stresses at the boundary are gradually rising, tending to reach the initial vertical pressure at the depth of the formation before the start of its mining. Tension zones relative to the horizontal and vertical stresses are identified, that are attributed to the areas of roof hang-up, which may determine the location of zones with higher methane and formation water permeability, both in the rocks between the seams and in the coal seam.


2022 ◽  
Vol 960 (1) ◽  
pp. 012023
Author(s):  
D I Poiană ◽  
I Ionel ◽  
G Drăghici

Abstract When perforation by cold plastic deformation processes of long round pipes, the technological problems appear primarily at the deformation of the part section, in the perforation area by losing the stability of the part, in the case of holes made at a distance from the pipe ends. The purpose of the research was to determine the influence of the constructive shape of the pipe clamping devices in the perforation area, in order to determine the device that offers the best stability of the section, to allow obtaining possible holes as large in diameter. The research was based on the application of materials strength methods and the Castigliano method of solving the indeterminacy, related to the process of cold plastic deformation. The research materialized by determining some calculation relations and specific diagrams regarding the diameter’s variation of the perforated holes in the air environment, depending on the dimensions of the part and the mechanical characteristics of the part material, for different forms of clamping devices. The calculations were performed considering that the perforation is performed in air, with a punch applied from the outside of the considered piece. The calculation relations and the obtained diagrams allow the determination of the maximum orifices, for certain dimensions of the pipes and for different mechanical characteristics of the part material. At the conclusions, a comparison was made of the results obtained for the variants of clamping considered devices and the optimal shape of the device was established, which allows the making of the largest perforated holes in the part.


2021 ◽  
Author(s):  
Oliver Plümper ◽  
David Wallis ◽  
Evangelos Moulas ◽  
Stefan Schmalholz ◽  
Hamed Amiri ◽  
...  

Fluid-rock interactions play a critical role in Earth’s lithosphere and in engineered subsurface systems. In the absence of chemical mass transport, mineral-hydration reactions will be accompanied by a solid-volume increase that may induce differential stresses and associated reaction-induced deformation processes, such as dilatant fracturing to increase fluid permeability. However, the magnitudes of stresses that manifest in natural systems remain poorly constrained. Here we show that the simplest hydration reaction in nature MgO + H2O⇔ Mg(OH)2 can induce stresses of several hundred megapascals, with local stresses up to ∼1.5 GPa. We demonstrate that these stresses are dissipated not only by fracturing but also induce plastic deformationwith dislocation densities (10^15m−2) exceeding those typical of tectonically deformedrocks. If these reaction-induced stresses can be transmitted across larger length scales they may influence the bulk stress state of reacting regions. Moreover, the structural damage induced may be the first step towards catastrophic rock failure, triggering crustal seismicity.


2021 ◽  
Vol 116 (8) ◽  
pp. 1849-1864
Author(s):  
Nicholas J.R. Hunter ◽  
Christopher R. Voisey ◽  
Andrew G. Tomkins ◽  
Christopher J.L. Wilson ◽  
Vladimir Luzin ◽  
...  

Abstract In many orogenic gold deposits, gold is located in quartz veins. Understanding vein development at the microstructural scale may therefore provide insights into processes influencing the distribution of gold, its morphology, and its relationship to faulting. We present evidence that deformation processes during aseismic periods produce characteristic quartz microstructures and crystallographic preferred orientations, which are observed across multiple deposits and orogenic events. Quartz veins comprise a matrix of coarse, subidiomorphic, and columnar grains overprinted by finer-grained quartz seams subparallel to the fault trace, which suggests an initial stage of cataclastic deformation. The fine-grained quartz domains are characterized by well-oriented quartz c-axis clusters and girdles oriented parallel to the maximum extension direction, which reveals that fluid-enhanced pressure solution occurred subsequent to grain refinement. Coarser anhedral gold is associated with primary quartz, whereas fine-grained, “dusty” gold trails are found within the fine-grained quartz seams, revealing a link between aseismic deformation and gold morphology. These distinct quartz and gold morphologies, observed at both micro- and macroscale, suggest that both seismic fault-valving and aseismic deformation processes are both important controls on gold distribution.


2021 ◽  
pp. 9-16
Author(s):  
S. Barsukov ◽  
А.Т. Batyrkhanova ◽  
Vladimir Dyomin

Purpose.  The published studies are aimed at determining the mechanism of deformation of the rocks of the contour around the workings in terms of the parameters of the emerging fracturing and their dependence on the indicators of the strength of the rocks and the depth of occurrence in the massif. The tasks of the study include the installation of fracture indicators, the determination of the parameters of the development of the deformation process around the working, including the effect of longwall mining and taking into account the possibility of reuse of the workings. Methodology. To solve the set tasks, the method of field observations was used together with the use of regression dependencies to determine the dependences of the parameters on the influencing factors. In addition, the method of full-scale pull-out tests of anchor support was used, which made it possible to determine the clamping forces of the anchors. Originality. In the course of the research, the dependences of stresses and deformation along the K7 coal seam in the conditions of the mine named after Kuzembaev CD JSC "ArcelorMittal Temirtau" for the massif around the mine with fastening. Rational parameters for the use of roof bolting in preparatory mine workings have been established. This type of fastening provides direct contact between rocks and lining. Analysis of the results of calculating the parameters of the roof bolting showed that to maintain the roof in the development workings, it is necessary to take into account the parameters of the roof bolting. The main parameters include the length of the anchors, the total resistance of the roof bolting and the density of the anchors. Anchor support forms laminated rock beams in the roof rocks, which ensure the stability of the workings. Conclusions and practical significance. The results of studies devoted to the establishment of the influence of mining-geological and mining-technical factors on the formation of zones of inelastic deformation in the host rocks were considered. Significant dependences of the deformation processes of rocks in the massif around the workings were obtained, and the parabolic zone of destruction of rocks was determined. The practical significance of the research consists in determining the actual indicators of the required bearing capacity of the anchorage at two levels in the conditions of the development of the coal seam k7 of the Kuzembaev mine.  


Author(s):  
M.K. Tupysev

The paper shows the development of technogenic axial loads acting on the column of casing pipes during the construction of directional wells. Axial loads depend on the angle of inclination of the wellbore trajectory and its length in the productive deposit, as well as from the timing of the input of the inclined-directed section of the trunk from the beginning of the development of the field.


2021 ◽  
pp. 54-62
Author(s):  
Ihor Babychev ◽  
Illia Mykhailovich Yevtushenko ◽  
Oleksandr Frolov

Purpose. The purpose of the research presented in the article is to substantiate the possibility of dump formation during joint dumping of quarry overburden rocks and iron ore wastes during the development of the Horishne-Plavnivsky deposit of iron quartzites. Task. Perform geomechanical modeling of the behavior of the quarry dump with the placement of funnels with enrichment wastes and establish the possibility of their joint storage in the dumps of the Horishno-Plavnivskoye deposit; to establish regularities of development of deformation processes in a dump in process of construction of each layer at dump of wastes of enrichment in funnels and to calculate a factor of a stock of stability of a dump after its formation. Research methods. To achieve the goal of research used: the method of complex analysis – to summarize previous research on the establishment and justification of the most rational method of dumping of enrichment waste; modeling methods – to establish the possibility and feasibility of joint dumping of enrichment wests and overburden rocks from the quarry. Scientific novelty. For the conditions of the Horishne-Plavnivsky deposit of ferrous quartzites by the method of geomechanical modeling the expediency and possibility of placement of dehydrated enrichment wastes in funnels on dump of overburden rocks is substantiated. Conclusions and practical significance of the article. For research results the predicted behavior of a dump during all term of its use is received. The obtained values of the maximum deformations are deviated in the process of its formation by each of layer and the investigated efficiency of deformation at formation of the following layer is established. The indicator of the coefficient of safety of the stability of the corresponding deviation after its formation and building, which means that it exceeds the minimum, in accordance with current regulations (n=1,329>1,3), after it is formation with further use joint dumping of overburden rocks and enrichment wastes is possible and appropriate.


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