complete deformation
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2022 ◽  
Vol 14 (2) ◽  
pp. 299
Author(s):  
Rui Wang ◽  
Kan Wu ◽  
Qimin He ◽  
Yibo He ◽  
Yuanyuan Gu ◽  
...  

For the accurate and high-precision measurement of the deformation field in mining areas using different data sources, the probability integral model was used to process deformation data obtained from an Unmanned Aerial Vehicle (UAV), Differential InSAR (DInSAR), and Small Baseline Subset InSAR (SBAS-InSAR) to obtain the complete deformation field. The SBAS-InSAR, DInSAR, and UAV can be used to obtain small-scale, mesoscale, and large-scale deformations, respectively. The three types of data were all superimposed by the Kriging interpolation, and the deformation field was integrated using the probability integral model to obtain the complete high-precision deformation field with complete time series in the study area. The study area was in the WangJiata mine in Western China, where mining was carried out from 12 July 2018 to 25 October 2018, on the 2S201 working face. The first observation was made in June 2018, and steady-state observations were made in April 2019, totaling four UAV observations. During this period, the Canadian Earth Observation Satellite of Radarsat-2 (R2) was used to take 10 SAR images, the surface subsidence mapping was undertaken using DInSAR and SBAS-InSAR techniques, and the complete deformation field of the working face during the 106-day mining period was obtained by using the UAV technique. The results showed that the subsidence basin gradually expanded along the mining direction as the working face advanced. When the mining advance was greater than 1.2–1.4 times the coal seam burial depth, the supercritical conditions were reached, and the maximum subsidence stabilized at the value of 2.780 m. The subsidence rate was basically maintained at 0.25 m/d. Finally, the accuracy of the method was tested by the Global Navigation Satellite System (GNSS) data, and the medium error of the strike was 0.103 m. A new method is reached by the fusion of active and passive remote sensing data to construct efficient, complete and high precision time-series subsidence basins with high precision.


2021 ◽  
pp. 63-69
Author(s):  
Anatolii Kryuchkov ◽  
Anatolii Bakhtyn

Purpose. The purpose of this study is to establish analytical patterns for predicting changes in stress and energy density spent on the destruction of rocks according to experimental studies. To solve this purpose in the article were set the following scientific problems: 1) analytical description of the dependence of the stress σij on the main deformation εij; 2) establishment of calculation parameters that are included in the analytical patterns; 3) analytical description and study of fracture energy density curves. Methodology. In the course of analytical and experimental researches of full diagrams of deformation of rocks the mathematical model of dependence of the stress on the deformation is developed. Physico-mechanical processes of all characteristic sections of the complete deformation diagram were also analyzed and described. Analysis of the resulting curve showed that the rock mass and elements of the lithosphere are not perfectly elastic or plastic objects. Along with the elastic ones, plastic ones are always present to one degree or another. The integration of the obtained analytical expression σ11 = f(ε11) allowed to establish the volumetric energy density spent on the destruction of the rock sample under the action of external load. The maximum activation energy for the considered rock is 0.67 MJ/m3. A comparison of the experimental and calculated values of the energy dependence u(ε1) shows a coincidence over almost the entire range of deformation changes (ε11 = 0..0.04). Findings. The study of rock samples at hard stress allowed to obtain a complete deformation characteristics of the rock. The curve that surrounds the deformation cycles (1) combines pre-boundary, boundary, extremal modes of deformation and destruction of rocks. Equation (4) allows us to establish that the destruction can occur at different values of energy density U(ε). Originality. An analytical description of the energy diagram of deformation and a complete diagram of stress change in the form of a single dependence, which takes into account the boundary and extremal areas, was developed in the work. In contrast to the method of piecewise linear approximation, this approach corresponds to the physics of the process and reduces errors in calculations. Practical implications. Theoretical and experimental analysis of the obtained energy fracture diagrams and complete stress change diagrams in rocks allows to estimate the bearing capacity of a rock mass or other solid body. This allows you to predict critical values of stresses and external loads to prevent failure in a timely manner.


2021 ◽  
Vol 929 ◽  
Author(s):  
Shubham Sharma ◽  
Awanish Pratap Singh ◽  
S. Srinivas Rao ◽  
Aloke Kumar ◽  
Saptarshi Basu

The multiscale dynamics of a shock–droplet interaction is crucial in understanding the atomisation of droplets due to external airflow. The interaction phenomena are classified into wave dynamics (stage I) and droplet breakup dynamics (stage II). Stage I involves the formation of different wave structures after an incident shock impacts the droplet surface. These waves momentarily change the droplet's ambient conditions, while in later times they are mainly influenced by shock-induced airflow. Stage II involves induced airflow interaction with the droplet that leads to its deformation and breakup. Primarily, two modes of droplet breakup, i.e. shear-induced entrainment and Rayleigh–Taylor piercing (RTP) (based on the modes of surface instabilities) were observed for the studied range of Weber numbers $(We\sim 30\text{--}15\,000)$ . A criterion for the transition between two breakup modes is obtained, which successfully explains the observation of RTP mode of droplet breakup at high Weber numbers $(We\sim 800)$ . For $We > 1000$ , the breakup dynamics is governed by the shear-induced surface waves. After formation, the Kelvin–Helmholtz waves travel on the droplet surface and merge to form a liquid sheet near the droplet equator. Henceforth, the liquid sheet undergoes breakup processes via nucleation of several holes. The breakup process is recurrent until the complete droplet disintegrates or external drag acting on the droplet is insufficient for further disintegration. At lower Weber numbers, the droplet undergoes complete deformation like a flattened disk, and a multibag mode of breakup based on RTP is observed.


Author(s):  
Oleksandr Shashenko ◽  
◽  
Vladyslava Cherednyk ◽  
Natalia Khoziaikina ◽  
Dmitro Shashenko ◽  
...  

Purpose. Justification of the gas collectors formation physical model on the basis of research of conformity of permeability of rock mass to the full diagram of rock sample deformation. Methodology consists in sequential analysis of the stages of the complete deformation diagram of the rock specimen under “hard” loading, comparing them with the stages of formation of the high stress zone in front of the lava bottom and statistical analysis of laboratory test results. Results. Based on the rock’s deformation properties analysis and their comparison with the rock sample full deformation diagram, the physical model of formation of gas reservoirs during the development of gas-saturated coal seam is substantiated. Within the solved problem framework, four stages of the complete deformation process are analyzed, namely: elastic, at the limit of strength, out-of-bounds stage and equivoluminal flow zone. The gas collector boundaries, which are the characteristic points of the rock sample deformation diagram in specified deformations mode (the limit of elastic strength and the limit of final strength) are determined. It is proved that the structural and textural features of the coal mass in connection with the course of gas-dynamic processes are manifested in the change in the pores and cracks volume contained in it, which together make the filtration space. Knowledge regarding the transfer of the permeability changes established regularities and free methane accumulation zones formation to the real rock mass, if the process of its forgery is considered as a consistent change of geomechanical states of rocks, is obtained. Scientific novelty lies in the first substantiated possibility of modeling the stress state before the longwall face by equivalent stages of the rock sample destruction in the given deformations mode. Gradual comparative analysis of the internal mechanism of rock samples deformation along the complete deformation diagram allowed establishing causal relationships between geomechanical and gas-dynamic processes in coal mass, and qualitatively characterizing general trends in permeability and volumetric expansion in changes of these samples. Practical value of the work lies in the justification of the principle of construction of a digital geomechanical model for the detection of man-made gas collectors in a mined coal mass.


2021 ◽  
Vol 13 (1) ◽  
pp. 45-53
Author(s):  
Roman Zinko ◽  
◽  
Orest Gorbay ◽  
Andriy Polyakov ◽  
Vitaliy Popovych ◽  
...  

The problem of truck cranes is considered, in particular, the issues of ensuring the strength of the supporting structure of the chassis in different modes of operation, taking into account the peculiarities of the technological cycle. In truck cranes, the load loads are unevenly distributed. They depend not only on the weight of the crane and the load, but also on the position of the rotating part of the crane relative to the non-rotating, as well as on the departure of the boom. Loads on the support surface are transmitted through the outriggers. During the operation of the truck crane, the load on each remote support does not remain constant. Estimated loads, namely loads from the crane installation and cargo, will take into account different values of cargo weight, departure and crane height. Their size and location are determined according to the crane capacity diagram. Based on the analysis of scientific works on the impact of subsidence of outriggers in the ground during the operation of truck cranes, it can be argued that this factor is quite significant and must be taken into account when calculating the strength of the truck crane. Moreover, the load on each of the supports is different and changes with each operating cycle, when changing the trajectory and working with different loads. Based on the comparative analysis of existing analogues, the limits of variation of the main technical parameters for the design of a family of special chassis for truck cranes are determined. The dangerous modes of operation of the truck crane, the influence of both the main parameters and external factors on the magnitude and nature of the load were calculated. The results of the calculations are plots of complete deformation, equivalent stresses and margin of safety. In maximum load mode, the main load falls on the rear of the frame and the rear outriggers. Maximum and minimum altitude modes are not particularly dangerous. In addition, the greater the height, the less dangerous is the high flight of the arrow. Large capacity is possible only on small flights and heights.


2020 ◽  
Vol 12 (2) ◽  
pp. 242 ◽  
Author(s):  
Kamila Pawluszek-Filipiak ◽  
Andrzej Borkowski

Underground coal exploitation often results in land-surface subsidence, the rate of which depends on geological characteristics, the mechanical properties of the rocks, and the applied extraction technology. Since mining-related subsidence is characterized by “fast” displacement and high nonlinearity, monitoring this process by using Interferometric Synthetic Aperture Radar (InSAR) is very challenging. The Small BAseline Subset (SBAS) approach needs to predefine an a priori deformation model to properly estimate an interferometric component related to displacements. As a consequence, there is a lack of distributed scatterers (DS) when the selected a priori deformation model deviates from the real deformation. The conventional differential SAR interferometry (DInSAR) approach does not have this limitation, since it does not need any deformation model. However, the accuracy of this technique is limited by factors related to spatial and temporal decorrelation, signal delays due to the atmospheric artifacts, and orbital or topographic errors. Therefore, this study presents the integration of DInSAR and SBAS techniques in order to leverage the advantages and overcome the disadvantages of both methods and to retrieve the complete deformation pattern over the investigated study area. The obtained results were evaluated internally and externally with leveling data. Results indicated that the Kriging-based integration method of DInSAR and SBAS can be effectively applied to monitor mining-related subsidence. The root-mean-square Error (RMSE) between modeled and measured deformation by InSAR was found to be 11 and 13 mm for vertical and horizontal displacements, respectively. Moreover, DInSAR technique as a cost-effective and complementary method to conventional geodetic techniques can be applied for effective monitoring fast mining subsidence. The minimum and maximum RMSE between DInSAR displacement and specific leveling profiles were found to be 0.9 and 3.2 cm, respectively. Since the SBAS processing failed in subsidence estimation in the area of maximum deformation rate, the deformation estimates outside the maximum rate could only be compared. In these areas, the good agreement between SBAS and DInSAR indicates that the SBAS technique could be reliable for monitoring the residual subsidence that surrounds the subsidence trough. Using the proposed approach, we detected subsidence of up to −1 m and planar displacements (east–west) of up to 0.24 m.


2020 ◽  
pp. 97-105
Author(s):  
I.A. Hodinev ◽  
◽  
S.A. Monin ◽  

The low cycle fatigue of heat-resistant nickel alloys with a single crystal structure VZHM7 and VIN3 was studied. The tests were carried out under conditions of monitoring the complete deformation in the cycle, loading of the type «tension-compression» occurred according to a sinusoidal law with a frequency of 0,5 Hz. For both alloys, tests were carried out for three crystallographic orientations ([001], [011], [111]) at two temperatures: 500 and 850 °C. Regression lines were constructed, the limits of limited endurance were found on the basis of 104 cycles. The influence of test temperature and crystallographic orientation on the endurance limit of alloys and RMS is analyzed.


Author(s):  
Tatyana Safonova

The author considers the problem of stylistic functions of linguistic units in modern Russian prose works through analyzing phraseological units in the detectives of B. Akunin. The article presents the most frequent types of phraseological units (idioms, set phrases, proverbs, sayings, popular expressions and other types of clichéd utterances) as representation of a personal literary style of this author. The research results point to their stylistic variety with high literary, colloquial, low colloquial, and slang units among them. The major types of phraseological unit conversion are distinguished as a prove of the writer's personal style, including, complete deformation of a component composition of a set phrase, reduction of the lexical length of phraseological units (implication), distribution of any component composition of the unit (explication), combining two or more phraseological units into a single set expression (contamination), replacement of a component in the composition of phraseological units with words of general literary layers (lexical variation), etc. The stylistic functions of all phraseological units under study are interpreted as retro-representation of the language of a certain time period, stylistic imitation of the communicative tone of oral speech, verbal characteristics of the characters who are referred to various social groups, and creation of humorous tone of the story. A comprehensive description of phraseological units used in modern fiction has revealed their artistic and stylistic potential.


2019 ◽  
Vol 9 (21) ◽  
pp. 4532 ◽  
Author(s):  
Xi Chu ◽  
Zhixiang Zhou ◽  
Guojun Deng ◽  
Xin Duan ◽  
Xin Jiang

In structural deformation monitoring, traditional methods are mainly based on the deformation data measured at several individual points. As a result, only the discrete deformation, not the overall one, can be obtained, which hinders the researcher from a better and all-round understanding on the structural behavior. At the same time, the surrounding area around the measuring structure is usually complicated, which notably escalates the difficulty in accessing the deformation data. In dealing with the said issues, a digital image-based method is proposed for the overall structural deformation monitoring, utilizing the image perspective transformation and edge detection. Due to the limitation on camera sites, the lens is usually not orthogonal to the measuring structure. As a result, the obtained image cannot be used to extract the deformation data directly. Thus, the perspective transformation algorithm is used to obtain the orthogonal projection image of the test beam under the condition of inclined photography, which enables the direct extraction of deformation data from the original image. Meanwhile, edge detection operators are used to detect the edge of structure’s orthogonal projection image, to further characterize the key feature of structural deformation. Using the operator, the complete deformation data of structural edge are obtained by locating and calibrating the edge pixels. Based on the above, a series of load tests has been carried out using a steel–concrete composite beam to validate the proposed method, with the implementation of traditional dial deformation gauges. It has been found that the extracted edge lines have an obvious sawtooth effect due to the illumination environment. The sawtooth effect makes the extracted edge lines slightly fluctuate around the actual contour of the structure. On this end, the fitting method is applied to minimize the fluctuation and obtain the linear approximation of the actual deflection curve. The deformation data obtained by the proposed method have been compared with the one measured by the dial meters, indicating that the measurement error of the proposed method is less than 5%. However, since the overall deformation data are continuously measured by the proposed method, it can better reflect the overall deformation of the structure, and moreover the structural health state, when compared with the traditional “point” measurements.


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