scholarly journals Practical Use of Measuring the Deflection of Roof Layers in the Assessment of the Stability of Mining Excavations in the Polish Copper Ore Mine “Polkowice-Sieroszowice”

Mining ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 13-31
Author(s):  
Lech Stolecki ◽  
Krzysztof Szczerbiński

The paper presents the results of long-term continuous measurements of the deflection of the roof layers in the underground copper mine Polkowice-Sieroszowice, Poland belonging to KGHM Polska Miedź S.A. The measurements were performed with the use of the inclinometric method consisting of continuous registration of changes in the angle of inclination of the roof strata. The measurements were carried out using an inclinometer sensor fixed to the end of a rockbolt in the roof. Measurements presented in the article were made in various regions of the underground mine. The monitoring covered: The exploitation front, machinery chamber and the region of the experimental longwall mining of copper ore. The obtained results proved the usefulness of the developed method in the process of the evaluation of the stability of mining excavations. The sensors were highly sensitive and performed the measurements in a simple way; highly accurate and reliable results were obtained.

2020 ◽  
Vol 12 (4) ◽  
pp. 1528 ◽  
Author(s):  
Ximin Cui ◽  
Yuling Zhao ◽  
Guorui Wang ◽  
Bing Zhang ◽  
Chunyi Li

Exhausted or abandoned underground longwall mining may lead to long-term residual subsidence on surface land, which can cause some problems when the mined-out land is used for construction, land reclamation and ecological reconstruction. Thus, it is important to assess the stability and suitability of the land with a consideration of residual surface subsidence. Assuming a linear monotonic decrease in the annual residual surface subsidence, the limit of the sum of the annual residual subsidence factor, and continuity between surface subsidence in the last year of the weakening period and the residual surface subsidence in the first year, we establish a model to calculate the duration of residual subsidence and the annual residual surface subsidence factor caused by abandoned longwall coal mining. The duration of residual surface subsidence increases with the increase in mining thickness as well as the factor of extreme residual subsidence. The proposed method can quantitatively calculate the annual residual subsidence, the accumulative residual subsidence, and the potential future accumulative residual subsidence. This approach can be used to reasonably evaluate the stability and suitability of old mining subsidence areas and will be beneficial for the design of mining subsidence land reclamation and ecological reconstruction.


2012 ◽  
Vol 170-173 ◽  
pp. 751-754
Author(s):  
Qun Song ◽  
Zhi Lin Yang

In accordance with the occurrence behavior of roof strata and the fracture characteristics of key stratum in shallow seam longwall mining, this paper studied the post-buckling behaviors of key roof stratum in the process of mining by using initial post-buckling theory, which derived a critical load and a breaking span of the main roof during the first weighting, determined the final subsidence for broken key stratum, and presented an application with the example of Daliuta 1203 face. The results indicate that the rock blocks a in are state of non-equilibrium after main roof breaking, the equilibrium path of main roof is unstable from breaking to final subsidence; thick unconsolidated layers above roof have effect on post-buckling behaviors of key stratum; the stability for bifurcation point equilibrium configuration and post-buckling equilibrium path of roof strata could be revealed and an effective method for determining displacement field of imperfection structure could be provided by using initial post -buckling theory.


2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Kiên Đặng Văn ◽  
Vo TRONG HUNG ◽  
Do NGOC ANH ◽  
Do NGOC THAI ◽  
Dao VAN CHI

The stability of deep underground mine drifts is pivotal to sustainable, safe mining in underground coal mines. The main objective of this research is to determine the stability and drifting safety issues in 500-m-deep deep underground mine drift through complex geology in the Quang Ninh coal area. The laboratory experimentation and field measurements were used to analyze the large deformations and failure characteristics of the surrounding rock, the influence factors of safe excavation and stability of deep underground mine drift, and to study the stability control countermeasures. This study also shows the main factors influencing the stability and drifting safety include complex geology zones, high in situ stress, poor mechanical properties and engineering performance of the argillaceous rock mass. According to the field study, the groutability of cement-matrix materials in the argillaceous rock in the complex geology zones were extremely poor, and deformations and failure of the surrounding rock were characterized by dramatic initial deformation, high long-term creep rate, obviously asymmetric deformations and failure, the rebound of roof displacements, overall loosened deformations of deep surrounding rock on a large scale, and high sensitivity to engineering disturbance and water immersion. Various geo-hazards occurred during the underground mine drift excavation, including roof collapse, groundwater inrush. Control techniques are proposed and should be adopted to ensure drifting safety and to control the stability of deep underground mine drift through complex geology zones, including choice of reasonable drift shape, reasonable support type, steel sets, regional strata reinforcement technique such as ground surface pre-grouting, primary enhanced control measures, grouting reinforcement technique, and secondary enclosed support measures for long-term stability, which are critical for ensuring the sustainable development of the underground coal mine.


2021 ◽  
Vol 3 (31) ◽  
pp. 119-132
Author(s):  
Eleonora Ratowska-Dziobiak

An efficiently operating financial system is considered as an integral part of a well-functioning economy. It is the mechanism by which services are provided that allow the flow of purchasing power. Thus, this system creates the foundations of activity for entities using money, enabling the conclusion of economic transactions in which money performs various functions. The result of the existence of this system is the possibility of co-creation of money by non-financial economic entities (enterprises and households) and the flow of cash between them. In the light of many transformations taking place in the financial system, it is extremely important to ensure its stability. A properly functioning financial system significantly supports the achievement of the main goals of the central bank – maintaining a stable level of prices, and thus creating the basis for achieving long-term economic growth. Educational activities are of great importance in ensuring the stability of the financial system. The aim of the article is to present the role of economic education among young people, thanks to which they can better understand the complexities of the functioning of the financial system, the importance of its stability and prepare to make more conscious decisions as fully-fledged participants of the financial market. Understanding the specificity of the available financial instruments enables the minimalization of the risk associated with their selection / purchase. The accuracy of decisions made in adulthood depends on the knowledge of basic economic issues and the awareness of potential threats.


2014 ◽  
Vol 1041 ◽  
pp. 19-22 ◽  
Author(s):  
Petr Selnik ◽  
Klara Necadova ◽  
Martin Mohapl

This article is focused on the assessment of the pitched turf green roof to the cardinal points, its permanent sustainable functional condition and investigation of a possible damage caused by local climate. The solution of these problems is the crucial factor in next development, use and expansion of this type of roofing in European broader range. This study of the roof construction that was made in Iceland offers conclusion based on quick changes of the local climate conditions and demanding extreme weather impacts. The main aim of this research is proposed the right possible solution and design of this construction including dealing with the details, select the convenient orientation to the cardinal points and surroundings to provide long-term stability of this construction.


Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.


1979 ◽  
Vol 42 (04) ◽  
pp. 1135-1140 ◽  
Author(s):  
G I C Ingram

SummaryThe International Reference Preparation of human brain thromboplastin coded 67/40 has been thought to show evidence of instability. The evidence is discussed and is not thought to be strong; but it is suggested that it would be wise to replace 67/40 with a new preparation of human brain, both for this reason and because 67/40 is in a form (like Thrombotest) in which few workers seem to use human brain. A �plain� preparation would be more appropriate; and a freeze-dried sample of BCT is recommended as the successor preparation. The opportunity should be taken also to replace the corresponding ox and rabbit preparations. In the collaborative study which would be required it would then be desirable to test in parallel the three old and the three new preparations. The relative sensitivities of the old preparations could be compared with those found in earlier studies to obtain further evidence on the stability of 67/40; if stability were confirmed, the new preparations should be calibrated against it, but if not, the new human material should receive a calibration constant of 1.0 and the new ox and rabbit materials calibrated against that.The types of evidence available for monitoring the long-term stability of a thromboplastin are discussed.


Author(s):  
Valery А. Gruzdev ◽  
◽  
Georgy V. Mosolov ◽  
Ekaterina A. Sabayda ◽  
◽  
...  

In order to determine the possibility of using the method of mathematical modeling for making long-term forecasts of channel deformations of trunk line underwater crossing (TLUC) through water obstacles, a methodology for performing and analyzing the results of mathematical modeling of channel deformations in the TLUC zone across the Kuban River is considered. Within the framework of the work, the following tasks were solved: 1) the format and composition of the initial data necessary for mathematical modeling were determined; 2) the procedure for assigning the boundaries of the computational domain of the model was considered, the computational domain was broken down into the computational grid, the zoning of the computational domain was performed by the value of the roughness coefficient; 3) the analysis of the results of modeling the water flow was carried out without taking the bottom deformations into account, as well as modeling the bottom deformations, the specifics of the verification and calibration calculations were determined to build a reliable mathematical model; 4) considered the possibility of using the method of mathematical modeling to check the stability of the bottom in the area of TLUC in the presence of man-made dumping or protective structure. It has been established that modeling the flow hydraulics and structure of currents, making short-term forecasts of local high-altitude reshaping of the bottom, determining the tendencies of erosion and accumulation of sediments upstream and downstream of protective structures are applicable for predicting channel deformations in the zone of the TLUC. In all these cases, it is mandatory to have materials from engineering-hydro-meteorological and engineering-geological surveys in an amount sufficient to compile a reliable mathematical model.


2018 ◽  
Vol 35 (4) ◽  
pp. 133-136
Author(s):  
R. N. Ibragimov

The article examines the impact of internal and external risks on the stability of the financial system of the Altai Territory. Classification of internal and external risks of decline, affecting the sustainable development of the financial system, is presented. A risk management strategy is proposed that will allow monitoring of risks, thereby these measures will help reduce the loss of financial stability and ensure the long-term development of the economy of the region.


2018 ◽  
Vol 940 (10) ◽  
pp. 54-64 ◽  
Author(s):  
I.A. Belozertseva ◽  
A.A. Sorokovoj

On the basis of long-term researches of soils in the territory of Russia and Mongolia soil and ecological division into districts of the Baikal region is carried out. At division into districts the whole set of an environment of soil formation was considered. On the map of soil and ecological division into districts 13 mountain, mid-mountain, low-mountain taiga, foothill, hollow-valley, forest-steppe and steppe provinces reflecting surface device originality as the ratio of balance of heat and moisture forming a basis to zoning is shown against the background of difficult orography are allocated. In total 42 districts on lithologic-geomorphological features are allocated. In formation of distinctions of a soil cover of these provinces the leading role is played by bioclimatic factors and inside them the lithologic-geomorphological ones. In the view of structural approach of the district they are considered as territories with a certain natural change of several types of the soil cover structure caused by features of a relief and the parent rock. The map is made in the MapInfo program. It is revealed that on ill-defined width zoning of soils the vertical one which has a greater influence on soils of this region is imposed. Soils of the Baikal region are not similar to the soils located at the same latitude of the flat European territory of Russia. Zone soils of this territory are specific and original.


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