Melih Iphar

В статье представлены результаты экспериментального исследования взрывного разрушения бетонных цилиндрических образцов с трубчатыми направляющими вставками. Изготовлено 27 образцов диаметром 76 мм и высотой 152 мм из бетона. В центральной части каждого образца пробурено отверстие диаметром 16 мм глубиной 120 мм. Испытаны три серии образцов: без вставок, с полутрубчатыми вставками и с перфорированными вставками. Вставки изготавливались из ПВХ, жести и тонкого пластика, имели наружный диаметр 14 мм и высоту 120 мм. Для создания напряженного состояния часть образцов обжималась металлическими хомутами по всей длине. Установлено, что образцы без трубчатых вставок разрушаются хаотично на 3–5 фрагментов, тогда как образцы с трубчатыми вставками распадаются на 2–3 части, причем трещина преимущественно ориентируется вдоль щели или перфорации. Отмечена перспективность применения полутрубчатых и перфорированных трубчатых вставок для управления трещинообразованием при взрывном разрушени Мақалада бағыттаушы түтікшелі кірістірулері бар бетон цилиндрлік үлгілердің жарылыстық бұзылуын эксперименталды зерттеу нәтижелері келтірілген. Бетоннан жасалған диаметрі 76 мм, биіктігі 152 мм болатын 27 үлгі дайындалды. Әрбір үлгінің орталық бөлігінде диаметрі 16 мм, тереңдігі 120 мм ұнғыма бұрғыланды. Үш серия сыналды: кірістірмесіз, жартылай түтікшелі кірістірмелермен және перфорацияланған түтікшелі кірістірмелермен. Кірістірмелер сыртқы диаметрі 14 мм, биіктігі 120 мм болатын ПВХ, қаңылтыр және жұқа пластиктен жасалды. Кернеулі күй жасау үшін үлгілердің бір бөлігі бүкіл ұзындығы бойынша металл қысқыштармен қысылды. Түтікшелі кірістірмесіз үлгілер 3–5 фрагментке ретсіз бөлінетіні, ал түтікшелі кірістірмелері бар үлгілер 2–3 бөлікке ыдырайтыны және жарықшақ саңылау немесе перфорация бойымен бағытталатыны анықталды. Жартылай түтікшелі кірістірмелер және перфорацияланған түтікшелі кірістірмелер жарылыс кезінде жарықшақ түзілуін басқарудағы маңызы атап өтілді The article presents the results of an experimental study on the explosive failure of concrete cylindrical specimens with tubular guiding elements. Twentyseven specimens with a diameter of 76 mm and a height of 152 mm were made of concrete. A hole of 16 mm in diameter and 120 mm in depth was drilled in the central part of each specimen. Three series of specimens were tested: without inserts, with half‑tubular inserts, and with perforated tubular inserts. The inserts were made of PVC, tinplate, and thin plastic; they had an outer diameter of 14 mm and a height of 120 mm. To create an stress state, some specimens were clamped along their entire length with metal clamps. It was found that specimens without inserts disintegrated randomly into 3–5 fragments, while specimens with tubular inserts broke into 2–3 fragments, with the crack propagating predominantly along the slit or perforation. The use of half‑tubular and perforated inserts is promising for controlling crack formation during explosive failure

Deciding on equipment from a set of feasible alternatives for excavation purpose in open pit mines is a critical task for the engineers and contractors since it considerably affects the project costs and productivity. Alternatives of rock excavation equipment, which are deemed suitable for the diggability of rock units in open pits, can have many technical specifications or factors that should be considered simultaneously. It can be successfully selected in a scientific way by employing multi-criteria decision making methods by means of taking the advantage of engineering knowledge, intuition and past experiences. In this study, we select the most convenient hydraulic excavator for a magnesite mine by fuzzy multi criteria decision making methods: fuzzy TOPSIS and fuzzy VIKOR. The fuzzy approach allows the experienced engineers to compare the multiple criteria (technical factors) and the possible alternatives of rock excavation machines by simply using linguistic expressions in their natural language.

The decision matrix method is preferred as a measure of risk evaluation considering the risk value obtained by two risk factors such as the likelihood and severity of a hazard. However, it has some deficiencies since a crisp risk score is assigned for likelihood and severity. In this article, a fuzzy logic-based safety evaluation method to enhance the risk assessment process is introduced to overcome the uncertainties encountered in the classical decision matrix risk assessment method. The proposed method is a more realistic evaluation of the risks which may be available in mechanized coal mines in Turkey. In this way, risky situations and operations in mechanized underground coal mines have been determined by expert knowledge and engineering judgement in linguistic forms. Thus, such an evaluation will be a valuable guide for coal mines in which fully mechanized coal production is expected in the near future.

A mobile application has been developed for selecting the most convenient underground mining method for a mine by employing well-known multi-criteria decision-making methods such as TOPSIS, VIKOR, ELECTRE, FMADM and PROMETHEE. The developed mobile application can carry out the selection process by prioritising valid alternative set of underground mining methods for taking into account some decision factors which are not considered in the conventional underground mining method selection approaches. In this way, the engineers are able to use this application for the selection of underground mining method on their mobile devices in anywhere.

Conventional geostatistical prediction methods can be used to carry out resource classification in ore beds and for reliability measurements. A field investigation based on lignite thickness data was conducted for resource classification in Eskisehir-Mihaliccik-Koyunagili coal basin. Moreover, a fuzzy logic-based resource classification method has been recently proposed to eliminate the uncertainties encountered in the conduct of conventional resource classification procedure. Fuzzy logic-based classification provides gradual transitions between two adjacent resource classes. In addition, the proposed method can classify each block by assigning a membership degree for handling decision-making problems encountered in conventional resource classification methods.

The rocks can be loosened either by drilling-blasting or direct excavation using powerful machines in opencast mining operations. The economics of rock excavation is considered for each method to be applied. If blasting operation is not preferred and also the geological structures and rock mass properties in site are convenient (favourable ground conditions) for ripping or direct excavation method by mining machines, the next step is to determine which machine or excavator should be selected for the excavation purposes. Many researchers have proposed several diggability or excavatability assessment methods for deciding on excavator type to be used in the field. Most of these systems are generally based on assigning a rating for the parameters having importance in rock excavation process. However, the sharp transitions between the two adjacent classes for a given parameter can lead to some uncertainties. In this paper, it has been proposed that varying rating should be assigned for a given parameter called as "continuous rating" instead of giving constant rating for a given class.