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 m2 area while the size increases up to 36 m2 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.

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