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1

Embankments Stability of an Opencast Mine with the Proposal of a New Mining Method For its Reopening (Kef Essennoun, Algeria)

Mezam M. C., Bachar Assed M. A., Ould Hamou M., Narsis Souad, Benselhoub Aissa

Inżynieria Mineralna

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2023

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no. 2, vol. 1

367--375

EN

The main purpose of our study is to treat the stability problem of the phosphate Kef Essennoun quarry in the mining field of Jebel Onk located in the Northeastern part of Algeria. To achieve these objectives, we started by monitoring the unstable area, using two monitoring systems: control stations and inclinometer. We then carried out a digital assessment of the Northwestern edge stability of the quarry, under the current operating conditions of exploitation. After that, we proposed a new operating plan for the reopening of the depot under the required security conditions. At the end, we carried out an assessment of the edge stability, as the work to reopen and develop the Kef Essennoun quarry progressed. The results show that, under the current operating conditions of exploitation, the Northwestern edge of the Kef Essennoun quarry is unstable (FS<1). The backfilling of the pilot pit of the mine, lead to the assurance of the mine walls stability, by increasing the values of safety factors with a rate of more than 30%. The backfilling of the pilot pit of the mine and the resumption of top-down mining exploitation will ensure the stability of the quarry during and after the operating exploitation mining. The study of the stability of the embankments bleachers, the edges of the quarries and the facings of the slag heaps during the open pit mining of useful ores deposits is an essential step that must be done gradually according to the development of mining works to guarantee the safety of personnel, materials, reserves and the environment.

PL

Głównym celem naszych badań jest rozwiązanie problemu stateczności kamieniołomu fosforytów Kef Essennoun w obszarze górniczym Jebel Onk zlokalizowanym w północno-wschodniej części Algierii. Aby osiągnąć te cele, rozpoczęliśmy od monitorowania niestabilnego obszaru przy użyciu dwóch systemów monitorowania: stacji kontrolnych i inklinometru. Następnie przeprowadziliśmy cyfrową ocenę stabilności północno-zachodniej krawędzi kamieniołomu w obecnych warunkach eksploatacji. Następnie zaproponowaliśmy nowy plan operacyjny dla ponownego otwarcia zajezdni w wymaganych warunkach bezpieczeństwa. Na koniec przeprowadziliśmy ocenę stabilności krawędzi w miarę postępu prac nad ponownym otwarciem i zagospodarowaniem kamieniołomu Kef Essennoun. Wyniki pokazują, że w obecnych warunkach eksploatacji północno-zachodnia krawędź kamieniołomu Kef Essennoun jest niestabilna (FS<1). Zasypanie wyrobiska pilotażowego kopalni doprowadziło do zapewnienia stabilności ścian kopalni poprzez zwiększenie wartości współczynników bezpieczeństwa o ponad 30%. Zasypanie wyrobiska pilotażowego kopalni i wznowienie odgórnej eksploatacji górniczej zapewni stateczność kamieniołomu w trakcie i po zakończeniu eksploatacji górniczej. Badanie stateczności obwałowań, krawędzi kamieniołomów i okładzin hałd żużla podczas odkrywkowej eksploatacji złóż rud użytecznych jest niezbędnym krokiem, który należy wykonywać stopniowo, zgodnie z rozwojem prac górniczych, aby zagwarantować bezpieczeństwo personelu, materiałów, zasobów i środowiska.

2

Control of Dump Stability Loading Rock on its Edge

Adamchuk Andrii, Shustov Oleksandr

Inżynieria Mineralna

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2023

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no. 1

91--96

EN

The question of the overburden rock dump formation during the development of iron ore deposits of Ukraine was considered. An analysis of the technology of forming a high single-tier dump in an abandoned deep pit was carried out. Two technology options are considered: loading rock on the slope of high single-tier dump and on its edge. The influence of the dependence of the loading rock on the edge of high single-tier dump on its stability of a has been established. The nature of the change in the width of the possible landslide prism, the safe distance of the dragline location has been established. The prospects for the formation of a high single-tier dump in the regime of controlled deformations are substantiated. For high single-tier dump the ordinary method of slices was justified and used to calculate the safety factor. Recommendations on the use of draglines available in Ukraine for forming the high single-tier dumps of overburden rock have been issued.

PL

W artykule rozważono kwestię powstawania nadkładu skalnego podczas eksploatacji złóż rudy żelaza na Ukrainie. Przeprowadzono analizę technologii formowania zwałowiska wysokiego jednopoziomowego w nieczynnym wykopie głębokim. Rozważane są dwa warianty technologiczne: załadunek skały na zboczu wysokiego zwałowiska jednopoziomowego oraz na jego krawędzi. Określono wpływ zależności skały obciążającej od krawędzi zwałowiska wysokiego jednopoziomowego na jego stateczność. Ustalono charakter zmiany szerokości ewentualnego graniastosłupa osuwiskowego oraz bezpieczną odległość położenia liny zgarniającej. Możliwości powstania wysokiego zwałowiska jednopoziomowego w reżimie kontrolowanych deformacji są uzasadnione. Dla wysokiego zrzutu jednopoziomowego zasadna była zwykła metoda przekrojów, wykorzystana do obliczenia współczynnika bezpieczeństwa. Wydano zalecenia dotyczące wykorzystania dostępnych na Ukrainie koparek do formowania wysokich jednopoziomowych zwałów nadkładu.

3

An early warning method for a slope based on the increment ratio of anchor cable internal force

Feng Jincai, Chen Jiaxin, Li Jian, Zhang Yu, Guo Jianhua, Qiu Hongyong

Archives of Civil Engineering

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2023

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Vol. 69, nr 1

553--569

EN

Prestressed anchor cables are active reinforcement to improve slope stability. However, the anchoring is not a permanent guarantee of stability, and the slope retains a potential risk of instability. From the perspective of the internal force of anchor cables, a new early warning method for the safety of the slope is provided, and a slope analysis model is established. With the increase in the strength reduction factor, the internal force increment curves of anchor cables under different prestresses are obtained. The point corresponding to strength reduction factors λ1 and λ2 represents a warning point. Key conclusions are drawn as follows: (1) The internal force of an anchor cable can be used to judge the stability of the slope strengthened by a prestressed anchor cable. (2) A warning index based on the internal force increment ratio of anchor cables is established. (3) The internal force increment ratio of anchor cables eliminates the influence of the initial prestress and is convenient for engineering applications.

4

Slope stability analysis under rainfall infiltration condition using the minimum potential energy method

Fang Weihua, You Rongqiang, Hou Hui, Sun Jiaping, Yu Tiantang

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e117, 2023

EN

Rainfall infiltration is a key factor to induce landslides, and it is important to study the rule of rainfall infiltration on slopes for the prediction and prevention of landslides. This paper combines the minimum potential energy method with the existing analytical solution of seepage field, and proposes a new method for unsaturated soil slopes under rainfall conditions. Specifically, the total potential energy function of the unsaturated soil slope is established by considering the real-time changes in system potential energy caused by rainfall infiltration. Additionally, the effects of rainfall infiltration on the shear strength of the soil, the self-weight of sliding mass and the seepage force are considered. The ratio of the slip resistance moment to the sliding moment is defined as the safety factor (SF) of the slope. The real-time evaluation of the stability of unsaturated soil slopes is realized during rainfall. The research results show that the results obtained by the proposed method are closer to the reference solutions. Meanwhile, the rules of rainfall intensity as well as slope angle on slope stability are conducted. Finally, the relationship between the sliding depth of failure surface and rainfall is also studied.

5

Kondycja dachu katowickiego Spodka w świetle aktualnych pomiarów sił w dźwigarach linowo-prętowych

Szydłowski Rafał, Łabuzek Barbara

Przegląd Budowlany

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2022

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R. 93, nr 5-6

88--92

PL

W pracy krótko opisano historię oraz układ konstrukcyjny Hali Widowiskowo-Sportowej Spodek w Katowicach. Nieco więcej uwagi poświęcono konstrukcji dachu oraz technologii jego realizacji. Przedstawiono w szczegółach budowę dachowego dźwigara linowo-prętowego, system naciągu i kontroli sił w linach nośnych. W pracy przedstawiono wyniki pomiarów kontrolnych sił w siedmiu ze 120 dźwigarów dachowych prowadzone od 1971 roku obejmujące również wyniki najnowszych badań przeprowadzonych w 2021 roku. Na podstawie prezentowanych wyników omówiono historię zmiany sił w dźwigarach od oddania obiektu do użytkowania do chwili obecnej oraz poziom bezpieczeństwa konstrukcji dachu w obecnym stanie.

EN

The paper briefly describes the history and construction of the Sports and Entertainment Hall Spodek in Katowice. A little more attention was paid to the roof structure and the technology of its implementation. The structure of the roof rope-rod girder as well as the tensioning and force control system in the lifting tendons are presented in detail. The paper presents the results of control measurements of forces in seven out of 120 roof girders carried out since 1971, including the results of the latest research carried out in 2021. On the basis of the presented results, the history of changes in the forces in the girders from the commissioning of the facility to the present day and the safety level of the roof structure were discussed.

6

Investigating the causes of stope instability at Golden Valley Mine

Sabao Ashley Ruvimbo, Munemo Prosper, Kolapo Peter

Journal of Sustainable Mining

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2022

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Vol. 21, iss. 2

128--140

EN

The study is based on mining operations that are concentrated in a ground exposed to flooding with varying stope dimensions. Stope stability was assessed in the four stopes, which resembled the mine’s different ground conditions using the stability graph complemented by the equivalent linear over break slough (ELOS) stability approach. The stability graph showed that the stopes in rock masses exposed to flooding fell in the potentially unstable and caving zones whereas the ones that were not affected by flooding fell in the stable zones. The ELOS approach showed that mining the previously flooded rock masses resulted in high over-breaks in the stopes despite them having smaller hydraulic radii. Therefore, it was deduced that although stope extension plays a part in the over-breaks experienced in different stopes, it is not the main cause of the overall stope instability. The results confirm the supposition that over-break is largely controlled by pore pressure than it is by blast induced stresses. Continuous implementation of the old support systems was no longer compatible with the state of the ground conditions. Hence, the mine should implement 6 × 8 m pillars, which have an acceptable factor of safety against failure.

7

Landslide stability analysis with the use of the design of experiments method – case study of souk ahras, Algeria

Charef Nouar, Mezhoudi Issam, Boumezbeur Abderrahmane, Harrat Nabil

Geomatics, Landmanagement and Landscape

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2022

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no. 4

137--150

EN

In the northeast of Algeria, Souk Ahras area is known for the severity and spread of landslides, especially in Mechroha and Zaarouria municipalities. Stability analysis of landslides in these areas depends on the calculations of safety factor according to several parameters (physical, mechanical, geological…). The aim of this study is to investigate the parameters affecting the safety factor using the design of experiments (DOE) method, central composite design (CCD) and response surfaces methodology (RSM). These methods use parameter modeling and optimization to discuss a solution of landslide hazard by developing models of safety factor (Fs) considered as response. The other parameters adopted as input independent factors are geotechnical physical and mechanical parameters such as: the dry and wet unit weight (γd, γh), the water content (w), the plasticity and liquidity limits and the plasticity index (WL, WP, IP), the percentage of fine elements Ff (%) < 0.08 mm), the cohesion C and the internal friction angle (Phi). Obtained results show high correlations with a regression coefficient R2 of 0.88 and 0.93 in the two cases study and the predicted factor of safety model fit best to those obtained in the analytical and numerical modeling procedure. The final model is applicable to give reliable results on the safety factor of landslides.

8

Consideration of the safety of bungee jumping in relation to mechanical properties of the installation based on a jump accident in Gdynia

Tomaszewska Agnieszka, Kłosowski Paweł

Engineering Transactions

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2022

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Vol. 70, iss. 4

407--424

EN

This paper considers a bungee jumping accident that took place in July 2019 in Gdynia, Poland. The authors conducted an investigation to determine the cause of the bungee rope failure. It was based on mechanical tests concerning the strength of the rope as well as the calculation of the force induced in the rope during the jump. Based on the theoretical and experimental results, the rope safety factor was estimated. It appeared to be three-fold lower than it is recommended in Polish regulations concerning ropes dedicated to lifting people for industrial and public purposes. However, no law regulations strictly concerning bungee installation makes it easy for accidents to occur.

9

Reliability-Based Assessment of Galloping Instability of Thin-Walled Steel Beams

Nguyen Huu Anh Tuan

Civil and Environmental Engineering Reports

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2022

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Vol. 32, no. 2

23--35

EN

Galloping instability relating to cross-wind vibrations can be found in flexible and lightly damped structures. In the present paper, the reliability of a thin-walled steel beam in maintaining its galloping stability was examined using a probabilistic approach. The analysis considered random variation in the cross-sectional geometrical properties of the beam, the material elastic modulus, the structural damping and the wind speed. A large number of Monte Carlo simulations were performed with normal and Gumbel distributions applied to the random variables to determine the probability distribution function of the safety margin. The limit state is considered violated when the wind speed exceeds the onset wind velocity of galloping, resulting in the aerodynamic damping being greater than the structural damping. It was shown by a conventional codified safety factor method that the beam was robust enough for galloping stability. By contrast, the probability-based assessment revealed that the beam failed to achieve the target reliability index in case the coefficient of variation of wind speed was greater than 5%. The analysis results suggested that the code-satisfied slenderness of the beam should be reduced by a factor of 1.5-1.7 under the action of wind speed with a coefficient of variation in the range 30-40%.

10

The influence of material characteristics on dam stability under rapid drawdown conditions

Utepov Yelbek, Lechowicz Zbigniew, Zhussupbekov Askar, Skutnik Zdzisław, Aldungarova Aliya, Mkilima Timoth

Archives of Civil Engineering

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2022

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Vol. 68, nr 1

539--553

EN

A fast reduction of a reservoir level may result in instability of an earth dam caused by the high pore water pressures that remain relatively high in the embankment. Moreover, the dissipation of the accumulated pore water pressures is highly dependent on the permeability of the materials used for the embankment and the storage characteristics of the reservoir. Therefore, in the design of embankment dams, the stability analysis under rapid drawdown loading conditions is an important design case. In this study, the influence of different permeability rates on dam stability under different cases of rapid drawdown was investigated using the finite element method in SEEP/W and SLOPE/W of the GeoStudio with a case of the Lugoda dam in Ndembera catchment, Tanzania. The modeling process considers the time-dependent hydraulic conditions and the transient flow conditions using different water levels during rapid drawdown for evaluation of the factor of safety. From the 1 m per day drawdown rate; the lowest minimum factor of safety value (0.90) was obtained from the 10-7 m/s material permeability of the upstream zone of the dam. It means that, at a drawdown rate of 1m per day, there is a potential for failure of the embankment if the hydraulic conductivity value will be somewhere below 10-6 m/s.

PL

Szybkie obniżenie poziomu zwierciadła wody w zbiorniku może wywołać utratę stateczność zapory ziemnej wynikająca z dużych wartości ciśnienia wody w porach pozostających w strefie odwodnej zapory. Rozpraszanie się ciśnienia wody w porach w zaporze ziemnej zależy od przepuszczalności materiałów użytych w nasypie oraz właściwości retencyjnych zbiornika. W projektowaniu zapór nasypowych analiza stateczności podczas szybkiego opróźniania zbiornika jest ważnym przypadkiem obliczeniowym. W niniejszym artykule przeanalizowano wpływ przepuszczalności materiałów na stateczność zapory przy różnych prędkościach szybkiego opróżniania zbiornika z wykorzystaniem metody elementów skończonych przy pomocy programów SEEP/W i SLOPE/W oprogramowania GeoStudio na przykładzie zapory Lugoda w Ndemberze zlewni w Tanzanii. W procesie modelowania uwzględniono warunki hydrauliczne zależne od czasu oraz przejściowe warunki przepływu przy różnych poziomach wody podczas szybkiego opróżniania zbiornika przy ocenie współczynnika stateczności. Przy szybkim opróźnianiu zbiornika wynoszacym 1 m na dobę zaobserwowano, że najmniejsza wartość współczynnika stateczności (0,90) uzyskano przy wartości przewodności hydraulicznej wynoszacej 10-7 m/s. Oznacza to, że przy prędkości obniżania poziomu wody w zbiorniku o 1 m na dobę, istnieje możliwość utraty stateczności nasypu, jeśli wartość przewodności hydraulicznej będzie mniejsza niż 10-6 m/s.

11

Optimization of heavy haul railway tunnel lining based on ultimate bearing capacity

Han Wei, Xiao Taoli, Shi Duanwen, Wang Yupeng

Archives of Civil Engineering

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2022

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Vol. 68, nr 4

493--511

EN

The optimization process of design parameters for composite lining of heavy haul railway tunnel is a key problem to be solved in tunnel engineering design. In order to put forward a better design scheme of composite lining for heavy haul railway tunnel, combined with field measurement and numerical simulation, the optimal working condition design is carried out by changing the thickness of shotcrete layer, the type of grid steel frame and the thickness of secondary lining. The influence of the above design parameters on the stress state of the composite lining is analyzed to obtain the optimal design parameters. Finally, the safety performance of the optimized lining is evaluated by the ultimate bearing capacity curve of the secondary lining section. The research shows that: 1) The optimal design parameters of the composite lining of the tunnel are the thickness of the shotcrete layer of 25 cm, the type of the grid steel frame of H180, the thickness of the secondary lining arch waist and the side wall of 40 cm and 35 cm respectively; 2) Different from the single-track heavy haul railway tunnel, the displacement value of the vault settlement of the double-track heavy haul railway tunnel is significantly greater than that of the inner convergence. Increasing the thickness of the shotcrete layer and changing the type of the grid steel frame have better effects on reducing the vault settlement, and have little effect on the inner convergence.

12

Stress-weighted spatial averaging of random fields in geotechnical risk assessment

Brząkała Włodzimierz

Studia Geotechnica et Mechanica

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2021

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Vol. 43, nr 4

465--478

EN

Effects of spatial fluctuations of soil parameters are considered in a new context – considering variability of soil parameters in conjunction with non-uniform stress fields, which can locally amplify (or suppress) subsoil inhomogeneities. In this way, several design situations for the Coulomb frictional material with random tan(φ(x)) reveal a reduction of variance, which is less significant than for the standard volume averaging. When looking for an 'effective' random variable [tan(φ)]a – that is, a random variable, which is equivalent to the random field tan(φ(x)) – the Vanmarcke averaging by simple volume integrals is insufficient; it systematically overestimates effects of variance reduction, thus causing potentially unsafe situations. The new proposed approach is coherent, formally defined and more realistic.

13

Analiza stateczności zapory ziemnej zbiornika Dzierżno Duże w warunkach filtracji nieustalonej

Sternik Krzysztof, Wolfram Eliza

Inżynieria i Budownictwo

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2021

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R. 77, nr 9-10

456--460

PL

Przeprowadzono analizę stateczności korpusu i podłoża zapory ziemnej. Wyznaczono wartości współczynnika stateczności w przypadku trzech wariantów zapory: bez przegrody przeciwfiltracyjnej, z przegrodą umiejscowioną w stopie skarpy odwodnej oraz z przegrodą w koronie zapory przy dwóch różnych poziomach piętrzenia zbiornika. Porównano wyniki obliczeń metodą elementów skończonych z wynikami uzyskanymi metodami równowagi granicznej.

EN

Stability analysis of the embankment dam and its substrate. Determination of the factor of safety for three embankment dam configurations: without an impervious barrier and with a barrier located at the upstream slope and in the crest of the dam. Two different flood surcharges taken into account. Comparison of calculation results by finite element method with results obtained by limit equilibrium methods.

14

Czy empiryczna metoda wymiarowania może zapewnić wzrost niezawodności i żywotności łańcuchów górniczych?

Philipp Günther, Kandzia Richard

Przegląd Górniczy

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2020

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T. 76, nr 6

25--34

PL

Wymiarowanie łańcuchów dla przenośników zgrzebłowych stosowanych w wyrobiskach ścianowych bazuje na założeniu uruchomiania zablokowanego przenośnika przy pełnym wykorzystaniu momentu maksymalnego zastosowanych silników. Autorzy analizują obraną metodykę, postulując przyjęcie korekt, których celem jest zwiększenie niezawodności i żywotności łańcuchów górniczych.

EN

The dimensional design of chains intended for armoured coal-face conveyors has traditionally been based on the imagined operating scenario of starting-up a stalled conveyor using the breakdown torque of the motors. The authors analyse this method and suggest to attain some adjustments in order to increase the operational reliability and the service life of mining chains.

15

Materiałowe współczynniki bezpieczeństwa płyt warstwowych

Konarzewski Andrzej

Izolacje

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2020

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R. 25, nr 11/12

A--49

PL

Materiałowe współczynniki bezpieczeństwa ɣM powinny odzwierciedlać zmienność właściwości mechanicznych płyt warstwowych, na co wskazują wyniki badań typu i zakładowej kontroli produkcji. Współczynniki te są określane na podstawie wyników testów. Początkowo mogą być określane na podstawie danych opartych na wartościach uzyskanych podczas badań typu, ale następnie należy je wyznaczyć na podstawie bieżących wyników zakładowej kontroli produkcji i w razie potrzeby odpowiednio skorygować.

EN

The material safety factors ɣM should reflect the variability of the mechanical properties of sandwich panels, as indicated by the results of type tests and factory production control. This factors are determined on the basis of test results. They may initially be determined on the basis of data based on the values obtained during type testing, but then they should be determined on the basis of the current results of factory production control and corrected if necessary.

16

Stability of anchored retaining walls under seismic loading conditions to obtain minimal anchor lengths using the improved failure model

Benamara Fatima Zohra, Rouaiguia Ammar, Bencheikh Messaouda

Civil and Environmental Engineering Reports

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2020

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Vol. 30, no. 3

214--233

EN

Anchored retaining walls are structures designed to support different loading applied in static and dynamic cases. The purpose of this work is to design and study the stability of an anchored retaining wall loaded with different seismic actions to obtain minimal anchor lengths. Mononobe-Okabe theory has been applied for the evaluation of seismic earth pressures developed behind the anchored wall. Checking the dynamic stability of anchored retaining walls is usually done using the classic Kranz model. To take into consideration the effects of the internal forces developed during failure, we have proposed a new model, based on the Kranz model, which will be used as the Kranz model to find the critical angle failure performed iteratively until the required horizontal anchor length is reached for a minimum safety factor. The results of this study confirm that the effect of the seismic load on the design of an anchored retaining wall, and its stability, has a considerable influence on the estimation of anchor lengths. To validate the modifications made to the new model, a numerical analysis was carried out using the Plaxis 2D software. The interpretation of the obtained results may provide more detailed explanation on the effect of seismic intensities for the design of anchored retaining walls.

17

Mathematical approach for estimating the stability of geotextile-reinforced embankments during an earthquake

Dahoua L., Usychenko O., Savenko V. Y., Hadji R.

Mining Science

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2018

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Vol. 25

207--217

EN

The Bishop’s method gives a safety factor of circular slip surfaces in excellent agreement with those given by the reliable bi-dimensional slices analysis methods such as Spencer, Janbu or Morgenstern and Price methods. However, several significant disturbing factors are not considered by the simplified or rigorous Bishop’s method on which depends a lot of commercial computer programs. This paper discusses a mathematical approach to take into account changeable values of cohesion and friction angle in the Mohr–Coulomb criterion in order to consider the reduction of intrinsic characteristics; adapt a new parameter (Fs) to take into account the behavior under seismic solicitations, introduce a force (r) to take into account the of infiltrated part of water. Finally stabilizing forces generated by the geotextile layers (Geo) are statically engaged in Boshop’s polygon of forces. The result shows that the seismic factor gives the main disturbing force to the slope equilibrium; whereas the geotextile action gives the main stabilizing force. In other words, this modified Bishop’s method is proposed to calculate cases for which the original method could not be used.

18

Application of FKM calculation algorithm for determination of degree of utilization of a milk tank wall

Lejman K., Fedorczuk R.

Agricultural Engineering

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2018

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Vol. 22, No. 4

33--41

EN

The objective of the paper was to determine the level of circumferential stress in a wall of an open milk tank and to assess the tank wall degree of utilization according to the FKM Guideline calculation algorithm - Analytical Strength Assessment of Components, Made of Steel Cast Iron and Aluminium Materials in Mechanical Engineering. (German: FKM - Forschungskuratorium für Maschinenbau). The stress level in the tank wall was determined based on analytical calculations and numerical method using the FEA - Finite Elements Analysis. Numerical calculations were made in FEMAP with NX NASTRAN Solver (NASTRAN - NASA Structure Analysis). Similar stress values were found using two independent calculation methods. The difference between obtained stress values does not exceed 2%. Based on the FKM algorithm, the safety factor jges = 1.4 and static capacity of the tank wall ask= 19.7% were calculated.

PL

Celem pracy było wyznaczenie naprężeń obwodowych występujących w ściance otwartego zbiornika na mleko oraz ocena stopnia wytężenia ścianki w oparciu o algorytm obliczeniowy FKM Guideline - Analytical Strength Assessment of Components, Made of Steel Cast Iron and Aluminium Materials in Mechanical Engineering, którego skrót (FKM) pochodzi od niemieckiej nazwy - Forschungskuratorium für Maschinenbau. Naprężenia wyznaczono w oparciu o obliczenia analityczne oraz obliczenia numeryczne z wykorzystaniem Metody Elementów Skończonych - MES. Obliczenia numeryczne wykonano w programie FEMAP z Solverem NX NASTRAN. Stwierdzono zbliżone wartości naprężeń przy zastosowaniu dwu niezależnych metod obliczeniowych. Różnica uzyskanych wartości naprężeń nie przekracza 2%. W oparciu o algorytm FKM obliczono współczynnik bezpieczeństwa jges =1,4 oraz wyznaczono statyczny stopień wytężenia ścianki zbiornika ask = 19,7%.

19

Studying the effect of a variation in the main parameters on stability of homogeneous earth dams using design experiment

Lakehal R., Djemili L.

Journal of Water and Land Development

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2017

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no. 34

173--179

EN

Deterministic approaches such as the limit equilibrium method (LEM) especially Bishop modified method has been traditionally used to evaluate the stability of embankment dams. However, the uncertainty associated with the material properties necessitates the use of the probabilistic method to account the sensitivity of this uncertainty on the response of the deterministic approaches. In this study, the authors propose the application of design experiment, especially central composite design (CCD) to determine the effects of independent uncertain parameters on the response of stability. A second-order polynomial model with cross terms is used to create an approximating function referred to as response surface for the implicit limit state surface, for which the input data were provided by stability analyses of different heights of homogeneous earth dams (10 m, 20 m, and 30 m) with a depth ratio of DH = 1.5 and a circular slip surface using the Bishop modified limit equilibrium method. The proposed models obtained from this application represent higher prediction accuracy. The study of the effect of geotechnical parameters (material properties of embankment) on safety factor show the importance of individual factors in level of linear effect with a positive effect of cʹ or φʹ and a negative effect of H, γd, γsat and significant influence of two-factors interaction, the effect of cʹ highly dependent on H, β, γd and φʹ. Moreover, the effect of φʹ is dependent on the values of H and β. Lastly, the optimization of safety factor with respect to the range of values of material properties was made, and two failures modes are discussed which are (φʹ, cʹ reduction and γd increase).

PL

Podejście deterministyczne, takie jak metoda granicznej równowagi (LEM), szczególnie w modyfikacji Bishopa, tradycyjnie było stosowane do oceny stabilności zapór. Niepewność związana z właściwościami materiału wymusza jednak użycie metod probabilistycznych, aby ocenić wrażliwość tej niepewności na podejścia deterministyczne. W przedstawionych badaniach autorzy proponują zastosowanie eksperymentu projektowego, w szczególności metody CCD (ang. central composite design), do określenia wpływu niezależnych niepewnych parametrów na stabilność. Zastosowano wielomianowy model drugiego stopnia do utworzenia funkcji aproksymacyjnej, czyli powierzchni odpowiedzi dla zadanej powierzchni stanu, dla której dane wejściowe dostarczyły analizy jednorodnych zapór ziemnych o różnej wysokości (10, 20 i 30 m), stosunku głębokości DH = 1,5 i kolistej powierzchni poślizgu z wykorzystaniem metody granicznej równowagi w modyfikacji Bishopa. Proponowany model otrzymany w wyniku tej aplikacji reprezentuje większą dokładność prognoz. Badania wpływu parametrów geotechnicznych (właściwości materiału, z którego zbudowano wał ziemny) na czynnik bezpieczeństwa wykazały znaczenie poszczególnych czynników w formie zależności liniowych z dodatnim wpływem cʹ lub φʹ, ujemnym wpływem H, γd, γsat i znaczącym wpływem dwuczynnikowej interakcji, w której wpływ cʹ był silnie uzależniony od H, β, γd i φʹ. Ponadto φʹ w dużym stopniu zależał od wartości H i β. Dokonano również optymalizacji czynnika bezpieczeństwa w odniesieniu do szeregu właściwości materiału i przedyskutowano dwie opcje niepowodzeń – zmniejszenie φʹ, cʹ i zwiększenie γd.

20

Zapas buforowy w magazynowaniu paliw płynnych determinowany współczynnikiem bezpieczeństwa. Cz. 2

Milewski R.

Autobusy : technika, eksploatacja, systemy transportowe

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2017

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R. 18, nr 6

1481--1484, CD

PL

W artykule zaprezentowano wpływ współczynnika bezpieczeństwa na poziom utrzymania zapasów gazu płynnego w magazynach podziemnych (kawernowych) zależnego od sposobu przeglądu zapasów.

EN

Storage processes play a key role in business operations. An indispensable factor in their proper operation is proper maintenance of stocks. They are a prerequisite for maintaining flow flexibility, and their size should be adapted to the level of distribution. The purpose of this article is to present the impact of the safety factor on the level of liquid gas stocks in underground storage (cavernous) dependent on the method of inventory review. The paper presents a theoretical basis for the theory of stocktaking and stocktaking and indicates the theoretical possibilities to exploit the importance of a safety factor on inventory levels.