Underground mining method assessment using decision-making techniques in a fuzzy environment: case study, Trepça mine, Kosovo

Purpose. The purpose of this paper is to reevaluate the currently used underground mining method with the intention to verify if cut-and-fill stoping method is appropriate for deep future excavation mining levels > 800 m below the ground surface. Methods. Decision-making methods i.e., Analytical Hierarch Process (AHP) and Fuzzy Multi-Attribute Decision-making Methods (FMADM), and UBC selection tool are implemented. Findings. According to UBC approach six alternatives – Block Caving, Cut-and-Fill Stoping, Sub-level Caving, Sub-level Stoping, Square Set Stoping, and Top Slicing have been considered as technically feasible alternatives. Results shows that cut-and-fill stoping method is the optimal mining method for deep excavation mining levels. Optimal underground mining method for Trepça mine due to the priority of this alternative (0.443) is the highest value compared with the other alternatives. Originality. This study attempts to find most suitable underground mining method among the possible alternatives based on AHP and FMADM techniques. Practical implications. In mine planning and design stage, mining method selection (MMS) for a mineral deposit is one of the most critical and challenging decision that experts have to make mainly based on geological, economical and geotechnical properties of the ore deposit.Мета. Оцінка ефективності сучасних способів підземної розробки та шарова виїмка із закладкою є адекватним способом для глибокої виїмки на глибинах 800 м і більше на основі теорії прийняття рішень. Методика. Були використані наступні способи прийняття рішень: аналітичний ієрархічний процес (АІП), нечіткі багатокритеріальні методи прийняття рішень (НБМПР) і вибір способу розробки методом Університету Британської Колумбії (УБК). При виборі способу розробки методом Університету Британської Колумбії в якості технічно доцільних було виділено 6 можливих варіантів розробки: поверхове обвалення, шарова виїмка із закладкою, підповерхове обвалення, підповерхо-камерна, виїмка із станковим кріпленням і шарове обвалення. Результати. Розроблено моделі прийняття багатокритеріальних рішень, що містять 4 основні критерії та 11 підкритеріїв для 4 альтернатив, що дозволило в порівнянні зі старими методологіями вибору методів видобутку обрати оптимальний метод підземних гірничих робіт науковим чином, зберігши при цьому лояльність і об’єктивність. Виявлено, що шарова виїмка із закладкою є оптимальним способом розробки на глибоких горизонтах. Так, для шахти “Трепча” даний спосіб підземної розробки є оптимальним, оскільки його ефективність за загальною оцінкою альтернативи (0.443) значно вище, ніж при інших способах розробки. Наукова новизна. Для умов шахти “Трепча” виявлено найбільш ефективний спосіб підземної розробки на основі методів прийняття рішень АІП і НБМПР. Практична значимість. При плануванні та проектуванні розробки вибір способу видобутку є найважливішим і часто ризикованим рішенням, яке фахівці повинні прийняти на основі аналізу геологічних, економічних і геотехнічних характеристик рудника.Цель. Оценка эффективности современных способов подземной разработки на глубинах 800 м и более на основе теории принятия решений. Методика. Были использованы следующие способы принятия решений: аналитический иерархический процесс (АИП), нечеткие многокритериальные методы принятия решений (НММПР) и выбор способа разработки методом Университета Британской Колумбии (УБК). При выборе способа разработки методом Университета Британской Колумбии в качестве технически целесообразных было выделено 6 возможных вариантов разработки: этажное обрушение, слоевая выемка с закладкой, подэтажное обрушение, подэтажно-камерная, выемка с креплением станковой крепью и слоевое обрушение. Результаты. Разработаны модели принятия многокритериальных решений, содержащие 4 основных критерия и 11 подкритериев для 4 альтернатив, что позволило по сравнению со старыми методологиями выбора методов добычи выбрать оптимальный метод подземных горных работ научным образом, сохранив при этом лояльность и объективность. Выявлено, что слоевая выемка с закладкой является оптимальным способом разработки на глубоких горизонтах. Так, для шахты “Трепча” данный способ подземной разработки является оптимальным, так как его эффективность по общей оценки альтернативы (0.443) значительно выше, чем при других способах разработки. Научная новизна. Для условий шахты “Трепча” выявлен наиболее эффективный способ подземной разработки на основе методов принятия решений АИП и НММПР. Практическая значимость. При планировании и проектировании разработки, выбор способа добычи является важнейшим и зачастую рискованным решением, которое специалисты должны принять на основе анализа геологических, экономических и геотехнических характеристик рудника.This study was financially supported by the Scientific Research Project Supporting Commission of Eskişehir Osmangazi University (grant number 201715A238)

A stability assessment of the rockfall problem around the Gokgol Tunnel (Zonguldak, Turkey)

WOS: 000413673700002The stability of rock slopes is an important area of interest in civil and mining engineering. This study investigated rockfall occurring around the Gokgol tunnel along the Zonguldak-Ankara roadway. Extensive field studies, including determination of geological description of the rock mass, scan-line surveys on discontinuities, identification of slope profiles, measurement of actual fallen block dimensions, and sampling procedures, were carried out. The study area and its surroundings are part of a Lower Carboniferous limestone formation. The assessments based on field studies indicated that two joint sets and a bedding plane were the main types of discontinuity. Two slope profiles were then created by considering the most frequently encountered rock fall events. The present study aimed to investigate the rockfall potential in this area by means of numerical analyses. For this purpose, RocFall software based on the lumped-mass method was utilized. Based on these analyses, traffic safety is threatened by potential rockfall. In Case I, a 30 % portion of the falling blocks reached the side of the main road, while about 70 % of them remained on the slope. However, falling blocks reached the end of the road in Case II. The study area requires some protection measures, such as the construction of retaining barriers and steel mesh to hold small size rock blocks. As a result, barrier heights to hold falling blocks were calculated as 0.5 m and 4 m for Case I and Case II, respectively. Barrier heights sufficient to hold falling rocks were determined using numerical analysis. In Case II, from such analyses, the energy required for a protection barrier for 1000 kg was found to be 200 kJ

3D Nonlinear Analysis of Ataturk Clay Core Rockfill Dam Considering Settlement Monitoring

WOS: 000462449600019One of the most important causes of damages in clay core rockfill (CCR) dams is the deterioration of the rockfill material over time and big settlements in the dam body. Therefore, the forecast of the settlements and principal stresses in a CCR dam is extremely important for the safety and future of these important water structures. In this study, changes in the nonlinear behavior of a CCR dam were examined by effects of the various reservoir water heights. Moreover, the geodetic measurements were confirmed with the nonlinear analysis results. Ataturk Dam, which is the largest CCR dam in Turkey, was selected for three-dimensional (3D) nonlinear analyses. First, a 3D finitedifference model of Ataturk Dam was created using the FLAC3D software, which is based on the finite-difference method. A Mohr-Coulomb material model was used for the dam body materials (e.g., clay core, filters, alluvium, rockfill) and foundation for the 3D numerical analyses. Numerical analyses were carried out for five various reservoir water heights: empty reservoir, 50, 100, 153, and 170 m (full reservoir). According to the finite-difference analyses, the effect of various reservoir water heights on the nonlinear behavior of the Ataturk dam was assessed in detail, and how much maximum vertical settlement will occur in the Ataturk Dam body in the future was determined. In addition, principal stresses and horizontal displacements were evaluated for each reservoir condition, and these results were compared with each other. This study demonstrated that as the reservoir water height increased at the upstream side of the dam, the principal stresses and verticalhorizontal deformations occurring in the dam body obviously changed and increased. In the second part of this study, the geodetic vertical settlement results observed by the General Directorate of State Hydraulic Works (DSI) between 1992 and 2013 were presented graphically. These geodetic observation results and numerical analyses were compared in detail, and the geodetic measurement results were confirmed by numerical analysis results. (c) 2019 American Society of Civil Engineers

Numerical modeling for the umbrella arch application at the shaft and tunnel intersection

© ISRM International Symposium on Rock Mechanics, SINOROCK 2009.In order to finish urban shallow tunnels (driven by NATM) projects as scheduled shafts should be sunk at certain intervals to form new excavation faces. Entering the tunnel from nearby shafts in addition to the tunnel axis to create new excavation faces is time consuming and costly. For this reason, to form new excavation faces directly from the shafts sunk in tunnel axis seems more economical. However, the greatest problem in such a study appears to be the stability. The stress accumulations at tunnel-shaft intersection areas contain hazard from the aspect of stability. Although it is not likely to face serious stability problems in strong rocks, this situation is potentially prone to reaching to dangerous levels especially in weak rocks. In this study, the stability at the shafts sunk in the tunnel axis and the intersection points of Goztepe station as part of the 2nd stage of Izmir Metro, was analyzed by numerical modeling. The accuracy of the numerical modeling results was later verified comparing with the results of in-situ surveys and measurements. During the study, shaft-tunnel intersection areas have been consolidated by umbrella arch method. The main reason for this strengthening was the obvious difference in the sizes of the shaft and the tunnel i.e., shaft crossectional area was smaller than that of tunnel. Therefore, stability of tunnel-shaft intersection area was designed accounting that the whole load of the shaft was to be carried by the tunnel support and the ground itself