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Загальна кількість знайдених документів : 8 Представлено документи з 1 до 8 |
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| 1. | 
Fredj M. Influence of the failure surface choice on the safety factor value during slope stability studies [Електронний ресурс] / M. Fredj, A. Hafsaoui, Y. Khadri, R. Boukarm // Науковий вісник Національного гірничого університету. - 2018. - № 3. - С. 30–35. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2018_3_6 Purpose. The aim of our work is to study the influence of the failure surface choice on the factor of safety for open-pit Phosphate mine case. Methodology. To estimate the influence of failure surface, our study is focalized on the case of the real slope with complex geometry (Kef-Essnoun Mine), where an important sliding has happened. Firstly, the safety factor (FS) was calculated with Limit Equilibrium Method (LEM) and three non-circular potential surfaces were chosen. Secondly, calculation of the safety factor was performed through the Finite Difference Method (FDM). Finally, the different values of FS obtained for the failure surfaces were compared in order to find the closest approach to what happened in our study case. Findings. The FDM is a useful tool for verification of LEM design due to precise calculation of the safety factor and a unique failure surface. Originality. The originality of this work is to use two different approaches, LEM and numerical method (FDM), for analysing the slope stability design and the accuracy of this method in mining engineering field. Practical value. This study illustrates that the results obtained by LEM in the cases (2) and (3) (FS - 0,920 the minimum value) of failure surface are almost identical to those obtained using the FDM (FS - 0,87), which reflects the reality of our case of study. On the other hand, in the case (1) LEM gives a contradictory result regarding that by FDM (FS - 4,345), the sliding does not happen (total stability). The close agreement between the two analysis methods indicates that the FDM can be used as a practical and meaningful verification of conventional LEM of complex slopes. | ||
| 2. |
Saadoun A. Numerical modeling of slope stability in Chouf Amar limestone quarry (M’sila, Algeria) [Електронний ресурс] / A. Saadoun, A. Hafsaoui, Y. Khadri, M. Fredj // Науковий вісник Національного гірничого університету. - 2018. - № 5. - С. 24-29. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2018_5_5 Purpose. The aim of this paper is numerical modeling of the slope stability of limestone quarry in dry and wet cases. Methodology. The study of slope stability was performed by the limit equilibrium method (LEM) through the SLIDE software, and numerical methods through PLAXIS and FLAC. Findings. In this study, the presence of water in the marl layer has a heavy influence on the safety factor (SF), which allows for instability of the slope. Originality. The originality of this work is based on two different approaches to determine the safety factor in the dry and wet cases through three methods, the limit equilibrium, finite element and finite difference methods (FEM, FDM). Practical value. This study has shown that numerical modeling of the slope stability using three methods, LEM, FDM and FEM can be expected to produce similar results. The different methods indicate that the finite difference method in our case is the most efficient and can be used as a practical check for the other methods. | ||
| 3. |
Nakache R. Stability analysis of the pillars of the underground mine Chaabet El-Hamra, Algeria by analytical and numerical methods [Електронний ресурс] / R. Nakache, M. L. Boukelloul, A. Bouhedja, M. Fredj // Науковий вісник Національного гірничого університету. - 2019. - № 2. - С. 21-27. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2019_2_5 Purpose. Analysis of the current and proposed room and pillar exploitation technique of the Zinc mine (Chaabet El-Hamra) by two different approaches, the tributary area (TAM) for analytical method and numerical method (Finite Element Method FEM) through PLAXIS 3D software. Methodology. In this work, the stability analysis of the room-and-pillar of the Chaabet El-Hamra mine was performed. Firstly, the safety factor for both conditions was calculated by TAM: 1) the current operation using 8,0 m wide rooms with 4,0 x 4,0 m pillar sections; 2) the proposed technique using 9,0 m wide rooms with 3,0 x 3,0 m pillar sections. Secondly, the numerical method was used to analyze pillar stability and total displacement of the proposed technique through the PLAXIS 3D software. Findings. Using more than one method in underground mining for analysis of the existing or proposed technique is the best solutions for achieving reliable results. Originality. The originality of this work is to use two different methods - TAM and numerical method (FEM) - for analyzing the rooms-and-pillars stability design at a mine and proving the accuracy of this method in mining engineering field Practical value. The results of the chamber and pillar stability analysis indicate a safety factor of 1,38 for the proposed technique. In addition, the maximum displacements are 0,259 mm. Thus, the proposed operating technique of the layer will not cause stability problems. The production ratios show that the extraction rate of the current technique is 89 % and for the proposed technique it is 93,75 %, so these results show that the proposed technique is advantageous and more practical. The stability studies confirm the fact that geotechnical research with computer applications (numerical methods) in underground mining can make a significant contribution to developing safer and more economical stopping methods with greater health responsibilities, security and environment. | ||
| 4. |
Boukarm R. Geotechnical risk assessment of rock slope stability using non-linear strength criterion [Електронний ресурс] / R. Boukarm, A. Houam, M. Fredj, R. Boucif // Науковий вісник Національного гірничого університету. - 2019. - № 4. - С. 48-54. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2019_4_10 Purpose. To assess the geotechnical risk of rock slope stability by empirical, numerical and Limit Equilibrium methods with the generalized Hoek - Brown criterion as a strength failure criterion to encompass all structural and geomechanical parameters influencing the stability of the open slope. Methodology. The study conducted risk assessment in three steps: risk identification, risk analysis, and risk evaluation. First, site observation and movement monitoring confirmed the real existence of instability risk. Then, from the in situ and laboratory investigations, an empirical classification called Slope Mass Rating, SMR and a geotechnical model were obtained. Finally, a quantification of this risk was evaluated using the limit equilibrium method and the finite difference method while considering the nonlinear criterion of Hoek - Brown as a criterion of failure. Findings. The non-linear generalized Hoek - Brown criterion can be used with some reliability in these stability studies since it takes into account the conditions of the discontinuities and the rate of fracturing within the rock mass. Originality. The method for geotechnical risk management was used based on the application of different approaches to quantify the geotechnical risk induced by the exploitation of this open pit. To attain the objective, the following techniques were involved: rock mass classification, geological strength index, limit equilibrium analysis. The philosophy of the research implies combining geometrical, structural and mechanical parameters to assess the rock slope stability. Practical value. This work has allowed us to conclude that SMR classification can be used as a prior check taking into account the structural and geometric context of the rock mass (orientation and integrity damage conditions, fracturing rates). The values of the safety factors of the extended Janbu's method and that of Morgenstern & Price are quite close to the method of finite differences (use of shear strength reduction technique). | ||
| 5. |
Fredj M. Back-analysis study on slope instability in an open pit mine (Algeria) [Електронний ресурс] / M. Fredj, A. Hafsaoui, H. Riheb, R. Boukarm, A. Saadoun // Науковий вісник Національного гірничого університету. - 2020. - № 2. - С. 24-29. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2020_2_6 Purpose. To analyze the sliding from the geotechnical point of view and to identify the plausible causes that influence it. Methodology. To analyze the sliding from the geotechnical point of view and to identify the plausible causes that influence it, our study follows the following chronological order. Firstly, a feedback reconstructs the slip from the geotechnical point of view; a back-analysis is required to confirm the surface failure. Next, a check will be made of the surface failure through the finite difference method and using the shear strength reduction by finite difference method (SSR-FD). A parametric study on the influence of the geometric parameters is performed to see the influence of the latter on the stability. The plausible cause that has directly influenced this sliding is shown. Findings. This paper considers the application of three methods: limit equilibrium method (LEM), finite element method (FEM) and finite difference method (FDM) to perform back analysis and find out the layer of slope failure in an open pit mine. Originality. Three different approaches LEM, FEM and FDM were used to perform the back-analysis the rock mass properties and to investigate the slope failure mechanism and the accuracy of this method in mining engineering field. Practical value. This study has illustrated that non-compliance with the art, open pit mining standards and early planning of the mining method can most often lead to critical situations and catastrophic results. The back analysis of the slip site allowed us to reconstruct the break already observed and to draw maximum lessons on the mode, location and mechanical parameters that triggered this break. | ||
| 6. |
Boustila A. Maximum surface settlement induced by shallow tunneling in layered ground [Електронний ресурс] / A. Boustila, A. Hafsaoui, M. Fredj, S. Yahyaoui // Науковий вісник Національного гірничого університету. - 2020. - № 5. - С. 55-60. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2020_5_10 Purpose. To improve the prediction of maximum surface settlement induced by tunneling in multi-layered soils. At the design stage, geotechnical experts tend to use simplified formulas for evaluating the ground response. Methodology. To examine the accuracy of empirical equations in predicting maximum surface displacement, two widely adopted formulas are considered for the current study: "Volume Loss" and "Farmer and Attewell". Moreover, because both equations are "inflection ratio" dependants, all existing expressions of the inflection parameter are taken in consideration. Finally, the obtained results are compared with field measurements, and the best pair of the expressions ("MSS" and "inflection ratio") is chosen. Findings. Prediction of the maximum surface settlement due to shallow tunneling in soft grounds is a valuable indicator in ensuring safe operations, particularly in urban areas. The current paper clarifies the advantage of the VL method over Farmer and Attewell fo all scenarios (variable overburden); high values of the VL improve the predictions significantly when it is combined with Dindarloo formulation of inflection ratio. Originality. The originality of this work is the examination of the most adopted empirical methods and all inflection point formulas, t estimate the maximum surface settlement induced by the construction of "Algiers Subway System" tunnel project; also, the paper demonstrated the weakness of some mostly used approaches through practical measurements. Practical value. Because of the lack of data in geotechnical engineering, this paper is a rich resource for tunneling projects in future because it covers over sixty measurement transverse profiles, and suggests numerical values for better assessment. | ||
| 7. |
Fellouh N. Assessment of geotechnical properties of Draa El Mizane highway tunnel (Algeria) [Електронний ресурс] / N. Fellouh, M. Boukellouh, A. Aissi, M. Fredj // Науковий вісник Національного гірничого університету. - 2020. - № 6. - С. 55-60. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2020_6_10 Purpose. To show the results of geotechnical studies and design the support system chosen in complex geological conditions especially in fault zones. The Draa El Mizane highway tunnel was a research site. Methodology. The determination of geotechnical properties by different classification systems for the quality of the rock mass such as the Q index, Rock Mass Rating RMR and the Geological Resistance Index GSI. In addition, the choice of the support system is validated by numerical modeling via the 2D Phase 2 program. Findings. The geotechnical measures developed through extensometer monitoring show a major compatibility between the geotechnical design and the digital simulation, which validates the reliability of the selected support system. Originality. A type of support chosen during construction is established, which corresponds to local specific conditions in order to eliminate instabilities. Practical value. The values obtained by numerical modeling can give us a final decision for the support system chosen: values in terms of deformations - in order of 1,5 cm at the top, 7,5 and 13,5 cm for the left and right wings respectively, 9,0 and 18 cm in the lower half left and right, 22,5 cm for the base of the tunnel. Furthermore, the results obtained by the measurements of instrumentation in the dimensioning of the support type are well illustrated through the measurements by an extensometer, which are very compatible with the results of numerical modeling. | ||
| 8. |
Boudiaf M. Assessment of potential dangers of installations at Rhourde Nouss station within the framework of The Law 45/DG (Ouargla, Algeria) [Електронний ресурс] / M. Boudiaf, R. Chaib, M. Fredj // Науковий вісник Національного гірничого університету. - 2021. - № 2. - С. 145-150. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2021_2_23 Purpose. According to the SONATRACH group s requirements, a hazard study should be carried out conforming to Law 45/DG in order to manage risk situations better and to ensure maximum operational safety. Methodology. The work presents modeling of accident scenarios through the ALOHA software. The identification and characterization of potential hazards of the facilities are carried out by the XRISK software while using the preliminary risk analysis method (PRA) and the bow tie method (in a horizontal plane). Finding. An assessment of the socio-economic impact in the event of an accident in the hydrocarbon industry is given as well as recommendations to avoid unforeseen consequences. Originality. For the first time at SONATRACH, the LOPA software has been used to model accident scenarios in the hydrocarbon industry. The latter refers to high-risk industries where every activity, whether industrial or commercial, is subject to incidents or serious situations that could seriously disrupt the operation of the organization, or even damage or destroy it. Practical value. Sensitive elements have been identified, which respectively include the station staff, the DSP agents on duty (digital signal processing), the subcontractors, i.e. a permanent population of 30 people on average. The occurrence of the potential major accidents identified in the risk analysis would cause the gas compression to stop at Rhourde Nouss station. Thus, there is a pressure drop at the level of the gas pipelines, which reduces the gas flow significantly, while its extent and duration will depend on the restarting of the station. Furthermore, the effects of damage to the equipment concerned could result in a significant cost for their replacement within a reasonable time. | ||
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