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ABSTRACT: Weathering has several effects on the physical, strength and material behaviour characteristics of rocks. Various researchers have attempted to obtain weathering classifications using qualitative and/or quantitative approaches. In this study, material behaviour under uniaxial loading conditions, mechanical and physical properties are investigated for reliable estimation of weathering degree of granodiorites. For this purpose, representative rock samples with different degrees of weathering from Havran (Balikesir/Turkey) were collected and the necessary investigations and tests were performed. Weathering grades ranging from unweathered (W0) to highly weathered rock (W3) were used for classification purposes. Core samples were tested in the laboratory to determine various physical and mechanical properties for each weathering class. Also, mineralogical properties of granodiorites were investigated and described for each weathering degree. Test results were used for analyzing and constructing prediction models with the aim of indirect determination of the weathering degree of granodiorites. Finally, a monogram was proposed to distinguish different weathering degrees under uniaxial loading conditions for rock engineering purposes. 1 INTRODUCTION Rocks, being conformed to technical specifications, are generally used as aggregates (cement aggregates, ballast aggregates etc.), filling materials (road embankment, joint filling material etc.), cover slab, brick and stone wall joints aimed to decoratively purposes in industry. Thus it is expected to increase production quality with detailed geological and geotechnical studies. A clear understanding of the weathering degree of rocks provides a great convenience in engineering applications. Various researchers have attempted to obtain weathering classifications using qualitative and/or quantitative approaches. Qualitative classification schemes are based on field observations and some simple index properties. Quantitative classification schemes are tightly coupled with mineralogical and physico-mechanical properties, strength and defor-mability characteristics of rocks. The progressive weathering in rocks lowers directly the quality of the rock materials and masses (Noble 1977, Fookes et al. 1988, Oyama et. al 1998, Yohta 1999, Wyllie 1999, Topal 2002, Arikan et. al. 2007, Marques et al. 2010).
Abstract Selection of support system is important for safety concerns and economic aspects. The purpose of this study is to investigate the design of support system specific to an underground mine in Balya, Balikesir, Turkey. The mine has been operated by Eczacibasi Group Esan Company since 2009 for lead and zinc production. Support systems were designed by using rock mass classification systems based on the data regarding underground openings, rock mass and support materials. The suitability of the designs were evaluated by using numerical methods to understand the effect of support materials by considering the difference between total displacement and strength factor both for supported and unsupported conditions. The effect of existing underground openings that are adjacent galleries were also simulated in the numerical models that could not be modelled in rock mass classification systems. The studies were completed a design procedure for a similar underground mines successfully. 1 Introduction Design of support systems is an important part of planning as well as site applications for a sustainable ore production. The studies are mostly carried out by considering in situ stress, stress around the openings, evaluation of rock burst, and squeezing conditions. Rock Mass Rating (RMR) proposed by Bieniawski (1989) and Q-system (Barton et al. 1974) classifications are employed as empirical methods to select support systems for underground openings. The results obtained from these studies can be combined to design underground opening's support system. These empirical methods similar with the analytical solutions mostly ignore the effect of existing underground openings. In order to obtain proper and optimized solutions during support design studies, some other methods such as numerical methods should be applied to understand the effect of other important features around underground openings. Underground mining with its complicated underground structures requires different solutions for support design problems due to its complicated and intricate structural relations based on underground mine production method. A lead and zinc underground mine is selected as a case study area that is operated by Eczacibasi Group Esan Company since 2009. The mine is located in Balya Balikesir, Turkey (Figure 1). A mineral processing plant with a daily capacity of 4,250 ton raw ore material has been also operating as a part of the mine. Production of the underground mine is sternly 4,250 ton per day, and the mine reaches 745 m depth for present. The mine is one of the important underground metalliferous mine in terms of its capacity, depth, and daily production rate in Turkey. Sublevel cut and fill stoping underground mining method has been applied for the production of ore. The ore is produced from sublevel production galleries where levels are constructed in every 15 m height. The open stopes are filled by cemented backfill material for the excavation of adjacent production galleries as well as forming working platforms for upper sublevel. The size of the production galleries are in rectangular shape with 25 m area while the size increases up to 36 m area since the mine goes down deeper. Fibrecrete, rock bolts, and wire mesh are the main support materials and engineering properties of these materials were also determined in order to simulate the suitability of support materials for underground openings.
Abstract Design of the fill or backfill material has been important subject for rock engineers due to the increase volume of underground mining operations as well as the environmental concerns raised from mineral processing plant tailings. Filling operations are useful for underground mining not only for the use of the opening as a tailing deposit but also to protect the mine against subsidence. The filled stopes are also safe working platforms for the production from downwards to upwards. The key issue to decide the applicability of tailings as paste fill material is the strength of the material. Paste fill mainly consists of water, tailing, and cement as binder material. A lead-zinc underground mine located in Balya, Balikesir, Turkey operated by Eczacibasi Esan Group was selected as site for the study. The mine was operated by sublevel stoping underground method, and it is the deepest metalliferous mine in Turkey with its high production rate. The underground openings are currently filled by cemented back fill material which mainly consists of aggregate, cement, and water. The aim of this study is to investigate the usability of process plant tailings as paste fill material. A series of tests were conducted for the different combination of paste material by changing the water and cement ratio as well as the slump. 12 different recipes for 5 different curing time were prepared to obtain the optimum mixture for paste fill that will be applicable for the mine. The results based on particle size distribution and strength properties such as uniaxial compressive strength and modulus of elasticity were used to select the most usable mixture as paste fill material for the underground mine. The use of paste fill will have an important effect on the cost of mining operation as well as environmental benefits.
ABSTRACT Production from Balya Lead-Zinc mine deposit located in the western part of Turkey restarted at 2009 that had been firstly mined by a French company at the end of 19th century. The mine operation method was projected as per underground sublevel stoping. Declined ramp will be used to reach the production face which is connected to the entrance portal with a main gallery. The 2400 m long main gallery as horseshoe-shape with 5 m width and height has 356 m elevation difference between entrance and final points and has been driven in two main formations which are limestone and dacite. Especially the contact zones of these two main formations are formed in a better way for water flow which mostly affects dacite rocks due to its high porosity that causes unstable conditions causing caving. The old abandoned French galleries also causes extra load on the support system while main gallery is intercepting and/or getting closer to them. The aim of this study is to design the support system of the main gallery related with the formation and properties of the rock mass, effect of the abandoned French galleries, and the shape of the underground openings. 1. INTRODUCTION Balya Pb-Zn underground mine located in the city of Balikesir of Turkey has been operated by Eczacibasi Esan Group since 2009. The deposit that was mined since the ancient times was also used as underground mine by a French company at the end of 19th century. The mine has been run by sublevel stoping method. Declined ramp has been used to reach to production face and a main gallery is also used to connect the mine to surface and the ramp. The main gallery will have served for the life of the mine for transportation of ore, waste, and labors, ventilation, and machinery transfers. Any inconvenience of main gallery’s support system will cause interruptions of the mine productions as well as safety problems which could not be acceptable for economical and safety reasons. The main gallery is 2400 m long, 5 m high and 5 wide in horseshoe shape and driven in two main rock formations that are limestone and dacite. Rock mass classifications are considered to perform the support design. Rock quality classification (Q) was selected to design of support for the main gallery . Added to that, rock mass rating (RMR) is also applied for further evaluation of the results as well . The results of rock mass classifications also shall be used to evaluate the possible unsupported span length as well as rock burst tendency of the openings. Geometry of the opening, mechanical and physical properties of intact rock material, properties of discontinuities, and in-situ stresses induced the depth of the opening, are considered in order to design the support system for the gallery . Rock bolts and fibrecrete are used as main structural components to design the overall support system. The rock mass around the opening mainly consists of limestone and dacite formations.