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1

Assessment of sinkhole hazard in the post-mining area using the ERT method and numerical modeling

Ścigała Roman, Szafulera Katarzyna, Jendryś Marek

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2023

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nr 75 (147)

20--34

EN

The loss of stability of shallow voids existing in the rock mass often results in the formation of sinkholes on the surface. This has a significant impact on the threat to public safety. Therefore, it is crucial to recognize the presence of such voids, especially in old post-mining areas, where shallow extraction was previously conducted, and there is a lack of mapping documentation indicating the location of underground workings. This paper presents an example illustrating a proposed procedure for recognizing shallow voids, which consists of two research works: geophysical research combined with numerical analyzes used as a kind of forward modeling. This combination increases the possibility of accurately locating potential sinkhole occurrences. The first part of this article provides selected literature information on the occurrence of sinkhole hazards. The second part presents the results of subsurface layer investigations of the rock mass conducted using electrical resistivity tomography (ERT). The third part focuses on assessing the threat of sinkhole formation by using forward numerical modeling performed with the FLAC 3D software to confirm the subsurface structures identified through the ERT method. The results of the analyzes conducted with both methods are then discussed in terms of their suitability for assessing the associated risk. The research conducted within the framework of this study confirms the effectiveness of the ERT method combined with numerical modeling for evaluating the state of the rock mass. This method can be considered a valuable tool for supporting decision-making in identifying post-mining areas that are particularly at risk of sinkhole formation.

2

Substantiation of a reasonable number of forklifts for a warehouse complex with frontal racks in an anylogic environment

Zhanbirov Galymzhan, Litvin Vadim, Taran Igor, Izteleuova Maral, Aliakbarkyzy Dana

Transport Problems

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2023

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T. 18, z. 2

147--160

EN

This paper is devoted to the study of the impact of volumetric planning solutions and the main production and technological parameters of a modern warehouse on the effectiveness of its functioning. The object of analysis is a class A warehouse complex located in Almaty. Simulation modeling was utilized to find and substantiate management decisions. The software product AnyLogic was used as the environment for the simulation. This paper develops a generalized algorithm for creating simulation models of warehouse complexes and a simulation model consisting of 114 blocks. The model is presented in the form of a black box, which made it possible to identify and establish correlations and relations between the input and output parameters of the warehouse, as well as its resources. A simulation experiment was conducted consisting of 63 model calculations. Variation parameters were the number of loading and unloading docks, as well as the number of forklifts in the storage area. As a result of the simulation, four options for the operation of the warehouse were established to ensure the unloading and loading of the required number of cars during the day. The optimal variant of the functioning of the warehouse complex was chosen on the basis of the proposed comprehensive criterion.

3

Analiza numeryczna wpływu przyjętych założeń projektowych w zakresie parametrów działania nagrzewnic elektrycznych na warunki panujące w hali produkcyjnej

Babul Konrad, Babul Krystiana

Instal

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2023

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nr 12

37--44

PL

Numeryczne symulacje przepływu, odwzorowujące modelowo rzeczywiste warunki pracy instalacji obiektów w dużej skali przemysłowej, umożliwiają jeszcze na etapie fazy projektowania na wykonanie analizy ryzyka i przeprowadzenie wielowariantowej parametrycznej optymalizacji ekonomiczno-technologicznej, celem dokonania wyboru najkorzystniejszego wariantu inwestycyjnego. W artykule przedstawiono przygotowany projekt koncepcyjny instalacji HVAC dla hali produkcyjnej o powierzchni 25 m x 10 m. W oparciu o przyjęte założenia projektowe wykonany został model 3D hali wraz z rozmieszczeniem przewodów nawiewno-wywiewnych oraz nagrzewnic elektrycznych, których praca miała zapewnić odpowiedni komfort cieplny w pomieszczeniu. Aby sprawdzić wpływ zmiany mocy cieplnej nagrzewnic elektrycznych na kształtowanie profilu prędkości i temperatury w hali produkcyjnej, stworzony został model matematyczny i model numeryczny CFD. Uzyskane rezultaty umożliwiły wyznaczenie pełnego rozkładu temperatur i prędkości w strefie przebywania ludzi, a przyjęta metodyka badawcza pozwoliła na przeprowadzenie analizy wpływu pracy nagrzewnic elektrycznych na warunki panujące w hali produkcyjnej.

EN

Fluid flow numerical simulations, which allow to modeling the real operating conditions of large-scale industrial installations, make possible to conduct risk analysis and multi-variant parametrical economic and technological optimization, to select the most favorable variant for investment at the design stage. The article presents the prepared conceptual design of the HVAC installation for a production hall with an area of 25 m x 10 m. Based on the set design assumptions, a 3D model of the hall was created along with the arrangement of supply and exhaust ducts and fan heaters, whose operation should ensure proper thermal comfort in the indoors. Mathematical model and numerical CFD model were created to verify the influence of power of fan heaters on the velocity and temperature contours in the production hall. The obtained results made it possible to determine temperature and velocity profiles in the people’s zone, and the adopted research methodology allowed to analyze the impact of the operation of fan heaters on the conditions in the production hall.

4

Influence of the disturbance created in the measuring channel on the readings of the hot-wire anemometric sensor

Nitkiewicz Szymon, Al-Jumaily Ahmed

Diagnostyka

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2023

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Vol. 24, No. 3

art. no. 2023315

EN

The research presents issues related to fluid mechanics, thermodynamics, and statistics. In the first sections, the authors review methods and parameters of fluid measurements. The work mainly emphasizes measurements concerning the parameters of air flows during human breathing. In the following section, the test bench for the analysis is described, and the methodology of data acquisition is described. Finally, the authors present a numerical model of the measurement channel and its calculations compared to measurements from an actual test stand. The data acquirement was performed with LabVIEW, modeling with COMSOL Multiphysics®, and calculations with MATLAB software.

5

On the merits of modified sublevel caving mining method – a case study

Adams Kenneth K., Chen Tuo, Sainoki Atsushi, Mitri Hani S.

Archives of Mining Sciences

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2023

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Vol. 68, no. 4

543--569

EN

Sublevel caving (SLC) mining method has several features that make it one of the preferred methods for ore extraction due to its high productivity and early access to ore recovery. However, there are some major challenges associated with the SLC method such as ground surface subsidence, high unplanned ore dilution, and the potential for air blast. To remedy these shortcomings, a recent approach has been to modify the SLC method by introducing rockfill into the void atop the production zone to provide continued support for the host rock and prevent it from caving. This paper discusses in detail the merits of the Modified SLC or MSLC. In comparison with other long-hole stoping methods that are predominantly practiced in metal mines, the MSLC method boasts several advantages. Early production achieved from the topmost level helps reduce the payback period. Productivity is enhanced due to multilevel mining without the use of sill pillars. The cost of backfilling is significantly reduced as there is no need for the construction of costly backfill plants. Continuous stoping is achieved without delays as mining and backfilling take place concurrently from separate mining horizons. A significant reduction in underground development costs is achieved as fewer slot raises and crosscuts are required for stope preparation. These merits of the Modified SLC method in steeply dipping orebodies are discussed by way of reference to real-life mine case studies. Dilution issues are addressed, and the benefits of top-down mining are explained. Typical mine design, ventilation, materials handling, and mining schedules are presented. Geomechanics issues associated with different in-situ stress environments are discussed and illustrated with simplified mine-wide 3D numerical modeling study.

6

Landslide triggered by small excavation – numerical simulations

Grodecki Michał

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

293--301

EN

The main objective of this work is to present the results of numerical simulations of the landslide triggered by small excavation. In south-eastern Poland in 2019, during excavation for a gas pipeline (relatively small – maximal depth 2.7 m), a landslide was observed. Length of the landslide was about 80 m, width about 50 m, maximal depth 6.5 m. Excavation was partially buried. Observed cracks of the terrain surface were wide, up to 0.8 m. Stability of the landslide was analyzed using the proportional reduction of the soil strength parameters (c-fi reduction) algorithm with the use of ZSoil.PC Finite Element Method (FEM) system. Stability analysis of the slope before and after excavation was performed, together with analysis of the tendency of the landslide to propagate upwards. The obtained stability loss modes were compared with the results of the field observations and a good correlation was noticed. Hypothesis that a landslide was triggered by small excavation was proved (although reasonable margin of safety was obtained for state before excavation, stability factor SF = 1.60). Use of residual soil strength parameters (instead of peak ones) and activation of cut-off (no tension) condition are advised. Presented methodology is open and can be used in engineering practice.

PL

Artykuł przedstawia wyniki symulacji numerycznych osuwiska wywołanego przez mały wykop. W południowo-wschodniej Polsce w 2019 r. w czasie wykopów związanych z wykonywaniem gazociągu (niewielkich, o maksymalnej głębokości 2.7 m) doszło do powstania osuwiska. Długość osuwiska wynosiła około 80 m, szerokość około 50 m, maksymalna głębokość 6.5 m. Wykop został częściowo zasypany przez osuwający się grunt. Zaobserwowano szerokie pęknięcia powierzchni terenu, o szerokości do 80 cm. Stateczność osuwiska analizowano z wykorzystaniem metody proporcjonalnej redukcji parametrów wytrzymałościowych gruntu (c-φ redukcji). Obliczenia wykonano za pomocą systemu Metody Elementów Skończonych (MES) ZSoil.PC. Analizowano stateczność zbocza przed i po wykonaniu wykopu oraz tendencję osuwiska do dalszej propagacji w górę stoku. Uzyskane mechanizmy utraty stateczności porównano z wynikami obserwacji terenowych i stwierdzono dobrą zgodność. Hipoteza, że osuwisko zostało spowodowane przez mały wykop została potwierdzona (mimo że w stanie przed wykonaniem wykopu zbocze posiadało wysoki współczynnik stateczności wynoszący 1.60). Zaleca się wykorzystywanie w obliczeniach stateczności rezydualnych wartości parametrów wytrzymałościowych gruntu oraz wykorzystanie warunku cut-off (oznaczającego brak wytrzymałości gruntu na rozciąganie). Prezentowana metodologia może być wykorzystana w praktyce inżynierskiej.

7

Performance of the polyurea‑coated steel tank under air blast load: a numerical study

Kiran K. K., Ahmad Shamsad, Al-Osta Mohammed A., Bahraq Ashraf A.

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e8, 2023

EN

Steel tanks are used in industries for several purposes, such as the storage of chemicals, water, oil, petroleum products, etc. These steel tanks are frequently exposed to internal explosions due to flammable vapor clouds and external explosives. Generally, two types of blast loads are identified, including surface blast load and air blast load. The air blast load is classified into cylindrical and spherical charges. This study attempted the air blast load mitigation of steel tanks using polyurea coating. A numerical model was developed to evaluate the response of the steel tank under air blast load in terms of internal energy, kinetic energy, strain energy, von-Mises stress, normalized base shear, and side overpressure response. In this regard, two different thicknesses (3.5 and 4.0 mm) of the polyurea coating were used. The model was successfully validated utilizing the previous experimental data. The numerical results indicated that the blast mitigation of steel tanks was effectively enhanced by applying the polyurea coating. In addition, the blast resistance increased with the increase in the thickness of the coating, where a reduction of 70% and 72% in displacements under different air blast loads were observed at the polyurea layer's thicknesses of 3.5 and 4.0 mm, respectively.

8

A description of the sources of magnetic field using edge values of the current vector potential

Wojciechowski R. M., Jędryczka C.

Archives of Electrical Engineering

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2018

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Vol. 67, nr 1

17--26

EN

The paper discusses the method of a description of the magnetic field sources in systems with the stranded windings. The sources are determined on the basis of an obtained distribution of edge values of the current vector potential T0. The formulas describing the magnetic field sources in the finite element (FE) space for the formulations using the scalar potential F and the vector potential A have been given. The approach for determining the T0 distribution in the stranded windings of simple and complex geometries has been proposed.

9

Numerical modeling of textile inspired three-dimensional woven timber structures

Duszyk Iwona, Sitek Marta

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2014

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No. 88

61--64

EN

Numerical modeling of textile inspired three-dimensional woven timber structures. The paper presents the numerical analysis of textile inspired three-dimensional woven timber structures. The numerical model built in ABAQUS 6.11 software simulated the possible behaviour of the structures under loading.