Risk assessment of blasting operations in open pit mines using FAHP method

Purpose. In the mining blasting operation, fragmentation is the most important output. Fly rock, ground vibration, air blast, and environmental effects are detrimental effects of blasting operations. Identifying and ranking the risk of blasting operations is considered as the most important stage in project management. Methods. In this research, the problem of identifying and ranking the factors constituting the risk in blasting operations is considered with the methodology of the Fuzzy Analytical Hierarchy Process (FAHP). Criteria and sub-criteria have been determined based on historical research studies, field studies, and expert opinions for designing a hierarchical process. Findings. Based on FAHP scores, non-control of the sub-criterion of health and safety (C3), blast operation results (C18) and knowledge, and skill and staffing (C2) with a score of 0.377, 0.334, and 0.294 respectively are the most effective sub-criterion for the creation of blasting operations risk. According to the score, the sub-criterion C18 is the most effective sub-criterion in providing the blasting operations risk. Effects and results of blasting operations (D8), with a score of 0.334 as the most effective criterion, and natural hazards (D10), with a score of 0.015, were the last priorities in the factors causing blasting operations risk. Originality. Regarding the risk rating of blasting operations, the control of the sub-criteria C3, C18, and C2, and the D8 criterion, is of particular importance in reducing the risk of blasting operations and improving project management. Practical implications. The evaluation of human resource performance and increase in the level of knowledge and skills and occupational safety and control of all outputs of blasting operations is necessary. Therefore, selecting the most important project risks and taking actions to remove them is essential for risk management.Мета. Визначення ризиків проведення вибухових робіт та їх оцінка на основі використанням нечіткого методу аналізу ієрархій (НМАІ) для покращення управління якістю проектів. Методика. В рамках даного дослідження, проблеми визначення та оцінки ризиків вибухових робіт розглядалися із застосуванням нечіткого методу аналізу ієрархій. На базі аналізу історичних даних і польового дослідження з урахуванням експертних оцінок були визначені критерії та підкритерії для побудови ієрархій. Результати. За результатами НМАІ, неконтролюючий підкритерій здоров’я та безпеки (С3), підкритерій результатів вибухових робіт (С18), знань, умінь і кадрів (С2) зі значеннями 0.377, 0.334 і 0.294 відповідно найбільш ефективні в появі ризику проведення вибухових робіт. Підкритерій С18 чинить найбільший вплив на ризик проведення вибухових робіт. Критерій результатів і наслідків вибухових робіт (D8) з найефективнішим значенням 0.334 та критерій природних катастроф (D10) зі значенням 0.015 є останніми пріоритетами серед чинників, які визначають ризик проведення вибухових робіт. Наукова новизна. Отримав доповнення та подальший розвиток науково-методичний підхід до визначення ризиків при проведенні вибухових робіт, заснований на їх ранжуванні з використанням системи виявлених критеріїв і підкритеріїв методом НМАІ. Практична значимість. Для успішного керування проектом важливо визначати найсерйозніші ризики проекту й вжити заходів щодо їх усунення. Відносно ранжирування ризиків проведення вибухових робіт управління підкритеріями C3, C18 і C2, а також критерієм D8, особливо важливо для зниження цих ризиків та покращення якості управління проектом.Цель. Определение рисков проведения взрывных работ и их оценка на основе использования нечеткого метода анализа иерархий (НМАИ) для улучшения управления качеством проектов. Методика. В рамках данного исследования, проблемы определения и оценки рисков взрывных работ рассматривались с применением нечеткого метода анализа иерархий. На базе анализа исторических данных и полевого исследования с учетом экспертных оценок были определены, критерии и подкритерии для построения иерархий. Результаты. По результатам НМАИ, неконтролирующий подкритерий здоровья и безопасности (С3), подкритерий результатов взрывных работ (С18), знаний, умений и кадров (С2) со значениями 0.377, 0.334 и 0.294 соответственно наиболее эффективны в появлении риска проведения взрывных работ. Подкритерий С18 оказывает самое большое влияние на риск проведения взрывных работ. Критерий результатов и последствий взрывных работ (D8) с самым эффективным значением 0.334 и критерий природных катастроф (D10) со значением 0.015 являются последними приоритетами среди факторов, которые определяют риск проведения взрывных работ. Научная новизна. Получил дополнение и дальнейшее развитие научно-методический подход к определению рисков при проведении взрывных работ, основанный на их ранжировании с использованием системы выявленных критериев и подкритериев методом НМАИ. Практическая значимость. Для успешного руководства проектом важно определять самые серьезные риски проекта и предпринять действия по их устранению. В отношении ранжирования рисков проведения взрывных работ управление подкритериями C3, C18 и C2, а также критерием D8, особенно важно для снижения этих рисков и улучшения руководства проектом.The authors would like to thank Mining Engineering Department, Islamic Azad University (South Tehran Branch) for supporting this research

Optimization of Chain Pillars Design in Longwall Mining Method

Chain coal pillars are parts of the structure of longwall mining system that play a significant role in the stability of the entries. With mechanization and developments in the various aspects of the method, higher efficiency in optimization of the design of chain coal pillars seems appropriate. In this paper, the three main methods of chain pillar design, namely the empirical, analytical and numerical methods are compared. Real data from the Tabas-Iran coal mines have been used in order to make the comparison process reliable. It is concluded that the most apparent advantage of the empirical method is the reliability of the results whilst the use of numerical methods enjoys the advantage of flexibility. On the other hand, the analytical methods are complex unless simplifying assumptions are made that can substantially decrease the accuracy of result which is thought to be the main advantage of the design method. A new method is therefore introduced here that combines all of the three presently used methods and by doing so, the new method has all the advantages of the three while minimizing complexities and inaccuracies associated with the use of the individual methods

Gold Nanoparticles Supported on Polyacrylamide Containing a Phosphorus Ligand as an Efficient Heterogeneous Catalyst for Three-Component Synthesis of Propargylamines in Water

Gold nanoparticles supported on a polyacrylamide containing a phosphinite ligand have been synthesized and characterized using different techniques such as TEM, SEM, EDX, XPS, and solid UV analyses. The new material was successfully applied as a heterogeneous catalyst for the three-component A3 coupling of amines, aldehydes, and alkynes to give propargylamines. Reactions are performed in neat water at 80 °C with only 0.05 mol% catalyst loading. The heterogeneous catalyst is recyclable during seven consecutive runs with small decrease in activity.The authors are grateful to Institute for Advanced Studies in Basic Sciences (IASBS) Research Council and Iran National Science Foundation (INSF-Grant number of 94010666) for support of this work. C. Nájera is also thankful to The Spanish Ministerio de Economia y Competitividad (MINECO) (projects CTQ2013-43446-P and CTQ2014-51912-REDC), FEDER, the Generalitat Valenciana (PROMETEOII/2014/017), and the University of Alicante for financial support

Seismic analysis of horseshoe tunnels under dynamic loads due to earthquakes

Due to seismic events, such as earthquakes, the elastic waves propagate through a medium. The impact of these waves on underground structures is to provide dynamic forces and moments that may affect the stability of underground structures. The aim of this paper is to analyse the effects of seismic loads on the stability of horseshoe tunnels. As a case study, the stability state of the main access entry to C1 coal seam of Tabas collieries in Iran are analyzed using Phase2 software in static and dynamic states. It is often assumed that the effect of earthquakes on underground structures such as tunnels is negligible but the results of this study show that the stress caused by seismic loads can be harmful to the tunnel stability. It is concluded that the stress and displacement balance of forces around the tunnel are adversely affected and due to redistribution of these forces that create undue concentration in some areas, instability occurs in the tunnel. The paper also concludes that increasing the stiffness of the support system can increase the effect of the seismic loads. The analysis provided in this paper together with the conclusions obtained can serve as useful tools for the tunnel design engineers, especially in areas susceptible to seismic phenomena

Designing a Mobile Application for Tourism in the Architectural Heritage of Tehran

Tehran has many valuable historical buildings as historical and populous capital. However, the increasing growth of the city and the uncontrolled prevalence of construction have endangered the city's architectural heritage in recent years. Introducing people to architecturally valuable buildings, and planning to visit them, reduces the risk of demolition. The purpose of this study is to provide a solution for tourism prosperity in Tehran's architectural heritage. This solution is defined in the form of a smartphone-based application. This study first identifies the needs and necessities of the users and measures the advantages and disadvantages of existing applications. Based on these preliminary studies, a model for designing a tourism application is proposed. Then, based on this model, the mechanism and different parts of the application are defined. The suggested application is an interactive and dynamic app. It is user-friendly and is constantly updated with the help of users. Users always encounter new experiences that other users created. The software user interface encourages the audience to be more active and encourages them to visit the building and protect it

Iron Oxide Nanoparticles Modified with Carbon Quantum Nanodots for the Stabilization of Palladium Nanoparticles: An Efficient Catalyst for the Suzuki Reaction in Aqueous Media under Mild Conditions

Magnetic Fe3O4 nanoparticles (NPs) functionalized with carbon dots (C-dots) that contain carboxylic acid and hydroxyl groups were synthesized successfully and used for the reduction of PdII and the formation of Pd NPs. The new material was characterized by SEM, TEM, energy-dispersive spectroscopy, solid UV spectroscopy, vibrating sample magnetometry, XRD, and X-ray photoelectron spectroscopy and was used as a very efficient catalyst in the Suzuki–Miyaura cross-coupling reaction of aryl bromides and chlorides with arylboronic acids in aqueous media. Design of experiments indicates that the use of 0.22 mol % of Pd, K2CO3 as the base, and aqueous ethanol are the best reaction conditions. The reactions of aryl bromides take place at room temperature, and aryl chlorides react at 80 °C. The easily synthesized and air-stable catalyst Pd@C-dots@Fe3O4 NPs could be separated from the reaction mixture by using an external magnet and reused in eight consecutive runs with no significant loss of catalytic activity.The authors are grateful to the Institute for Advanced Studies in Basic Sciences (IASBS) and the Iran National Science Foundation (INSF-Grant number of 94010666) for support of this work. C.N. is grateful to the Spanish Ministerio de Economia y Competitividad (MINECO) (projects CTQ2013-43446-P and CTQ2014-51912-REDC), FEDER, the Generalitat Valenciana (PROMETEOII/2014/017), and the University of Alicante for financial support

Magnetic nanoparticles supported oxime palladacycle as a highly efficient and separable catalyst for room temperature Suzuki–Miyaura coupling reaction in aqueous media

A novel magnetic nanoparticle-supported oxime palladacycle catalyst was successfully prepared and characterized. The magnetically recoverable catalyst was evaluated in the room temperature Suzuki–Miyaura cross-coupling reaction of aryl iodides and bromides in aqueous media. The catalyst was shown to be highly active under phosphine-free and low Pd loading (0.3 mol%) conditions. The catalyst could be easily separated from the reaction mixture using an external magnet and reused for six consecutive runs without significant loss of activity.The authors are grateful to Institute for Advanced Studies in Basic Sciences (IASBS) Research Council and Iran National Science Foundation (INSF-Grant number of 93020713) for support of this work

3D strain softening modelling of coal pillars in a deep longwall mine

In longwall coal mines, the entries on both sides of the panel play a significant role in production rate and safety of operation. With increasing production amount, the rate of conveying material through such entries increases. Therefore, it is required to design wider entries. Support of these entries, particularly in deep mines is difficult. In this paper, by using FLAC3D program code a deep longwall coal mine is modeled. The coal seam has a strain softening property, and the analysis index of stress and deformation of ribsides and coal pillars at different loading levels are determined. Strain softening parameters is studied separately for each modeled coal pillar, and based on conventional formula the pillar strength are calculated. In a modeled longwall mine, the caving material at goaf zone are fully compact. The results shows that based on Mohr-Coulomb model, the strain softening occurs at maximum cohesion and friction, and at region of decreasing the strength of pillar in stress-strain curve. Because of 3D nature of analyses, the effect of front and side abutment load on stability of pillar are studied simultaneously. Therefore, the results of this study could be suitable criteria for appraisal of pillar design method at deep longwall coal mines

Estimation of Coal Pillar Strength by Finite Difference Model

Longwall mining is now predominately used in coal mines where somewhat difficult conditions exist. As in the case of all other underground mining methods, pillars are integral parts of the mining design. The choice of shape and dimensions of the pillars has significant impact on the recovery and hence on overall productivity of the mine. The process of pillar design in longwall mining entails the selection of a safety factor, which is done by estimating the magnitude of the load applied on the pillar and the load bearing capacity of such pillars. In this paper, finite difference modeling principles have been applied to a typical coal pillar. The pillar strength is then estimated with various width/height ratios. These results have been compared with the results obtained from the conventional methods of pillar design. The effect of roof and floor quality on the strength of the typical pillar has also been evaluated in the same manner. It is concluded that although the finite difference method is not always the perfect method for such estimation, but the results clearly demonstrate that it produces more acceptable design than the conventional method, especially under undesirable conditions regarding the interface between pillars, roof and floor. An additional advantage of such method is shown to be its capability of being applied in situations where complex parameters prevail