ABSTRACT Undoubtedly, Roadheaders are one of the most versatile excavation machine types operated in soft and medium strength rock formation's tunneling and mining. An essential aspect of a successful roadheader application is definitely the performance prediction which is basically concerned with machine selection, production rate and also bit consumption. Evolving a new roadheader's performance prediction model in various operational conditions and also different material is the primary intention of this research. Investigation on previous works revealed that three main features have great influences on the bit wear of a roadheader. Brittleness which can be utilized as a cuttability factor in mechanical excavation perspective is actually one of some parameters which is absolutely in relation with breakage properties. In addition to the rock brittleness, rock quality designation (RQD) and instantaneous cutting rate are employed as input parameters for the prediction of pick (bit) consumption rate (PCR). For the purpose of this paper, using previously published field datasets, a new prediction model using the application of artificial neural networks as an artificial intelligence technique is developed, trained and tested to estimate PCR based on data of brittleness, RQD and instantaneous cutter rate. Results demonstrated that PCR is highly correlated to the input parameters, and the ANN model could produce acceptable predictions. INTRODUCTION In recent years, mining business has been under the influences of global trends, environmental limitations, and variant market requirements to be more and more productive and profitable. Utilizing mechanical miners like roadheaders, continuous miners, impact hammers and tunnel boring machines for ore extraction and excavation of development drivages, increases profitability. The mentioned miners result in continuous operations and consequently, the mechanization of mines with mechanical miners is presumed to make mining projects more productive, more competitive, and less costly. As a result, ordinary drill and blast technique could be avoided. Roadheaders which are applicable in tunnelling, mine development, and mine production of rock types of soft to medium strength, are very adaptable excavation facilities. The efficiency of roadheader application is rudimentary related to machine selection, production rate and bit consumption (Ebrahimabadi et al., 2011).

Abstract The paper introduces design principles of ground support. The topics include underground loading conditions, the natural pressure arch in the rock mass, design methodologies, determination of the factor of safety and compatibility between support elements. A natural pressure arch is formed in the rock mass in a certain distance behind the tunnel wall. The methodology of ground support in an underground opening is dependent on the size of the failure zone and the boundary depth of the natural pressure arch. In the case of a small failure zone, rockbolts should be long enough to reach the natural pressure arch. In the case of a vast failure zone, an artificial pressure arch could be established in the failure zone with tightly spaced rockbolts and the artificial pressure arch is stabilised with long cables anchored on the natural pressure arch and/or by external support elements like shotcrete liners, girdles, steel arches and shotcrete arches. In addition to the factor of safety, the maximum allowable displacement in the tunnel and the ultimate displacement capacity of support elements should be also taken into account in the design. Finally, the support elements in a ground support system should be compatible in terms of displacement and energy absorption. 1. Introduction Ground support design is associated with the rock mass quality, the in situ stresses and the size and geometry of the underground opening. Knowledge of the in situ loading condition is crucial for the design of ground support. The methodology and design principles of a ground support program are determined by the potential failure mode and failure extent of the rock mass as well as the engineering requirements to the maximum allowable displacement. In this paper, some key parameters for ground support design are presented which include the natural pressure arch, the artificial pressure arch established in the failure zone, support layers, the factor of safety, and the compatibility between support elements.

ABSTRACT Mining and chemical industries have investigated Thin Spray-on Liners (TSLs) intensively in the past. Mining suppliers, contractors and universities have been promoting a concept, or better, a vision of so called ‘Thin Support Liners’ (TSLs). It is a wish of the industry that sprayed concrete and mesh could be replaced by these thin liners. All TSLs are meant to be applied in 3–10 mm layers and consist of a certain polymer content. EFNARC (Experts for Specialized Construction and Concrete Systems is an European federation which unites national associations and companies involved in concrete repair, flooring, sprayed concrete and the protection and repair of tunnel and mining constructions) changed the meaning of the abbreviation "TSL" to "Thin Spray-on Liner" in 2008. This definition change included a clear reduction to the expectations regarding TSLs. Even though TSLs give a certain amount of surface support, they act more as sealant. Today the usage is mainly accepted in coal mines in certain countries, even though some applications in kimberlite or shaft sinking have shown success. Now Normet is introducing a new product called TamCrete SSL a ‘Structural Support Liner’ to the tunneling and mining industry. This new product is introduced as a spray applied, rapid curing, non-toxic resin based support liner for mining environments. The paper will cover the basics of TamCrete SSL including key mechanical figures and application methods. The paper will also show field test which indicate its waterproofing characteristics. These tests were first carried out as a part of master's thesis and based on these tests the waterproofing characteristics of a cured product seem to be good. INTRODUCTION For decades the underground construction industry has used shotcrete for rock support in tunnels. However, shotcrete takes time to cure which slows down the excavation process. In addition shotcrete forms cracks during curing and water might funnel into the tunnel through these cracks. Now Normet Oy has brought a new kind of Thin Sprayed Liner on the market. This material is called TamCrete SSL (Structural Support liner).

ABSTRACT The ability to use cutting edge tools, such as numerical modelling, to predict seismically active volumes is a clear goal of today's geomechanical engineers. A knowledge of problem volumes in advance of drifting and production would lead to a safer working environment, where risk mitigating design can be implemented. While specific successful cases exist, a standard approach for numerical stress analysis of seismicity is not currently available in the literature. This paper presents the use of numerical modelling to analyse seismically active volumes of Luossavaara- Kiirunavaara AB's (LKAB) Kiirunavaara Mine, a 4.5 km long, iron orebody extracted using sublevel caving. Crack initiation and slip along pre-existing discontinuities were evaluated using Itasca's FLAC3D software and compared to mine seismicity. Results were used to evaluate expected changes in seismically active volumes with planned production. Hanging-wall seismicity was correlated with the location of plastic failure in the models, as well as differential stress near the production front. Less clear relationships existed between footwall seismicity and model results, however, many orientations of discontinues have the possibility to slip, and therefore may contribute to seismicity. Patterns in orientations of discontinuities that can slip were consistent in the footwall drifts relative to the active production level, regardless of the depth of production evaluated. In general, the models did not indicate any expected changes in seismically active volumes with planned production. 1. INTRODUCTION It is undisputable that an understanding of the phenomena of seismicity in rock masses will improve mine safety. Although prediction of specific seismic events does not seem achievable (e.g. McKinnon, 2006), identification of areas that have a higher risk of seismic activity seems within reach. Numerical stress analysis models are the leading-edge tools to understand rock mass behaviour, and much effort has been put towards the modelling of seismicity (e.g. Diederichs, 2000; Andrieux et al. , 2008; Beck et al. , 2009; Sjöberg et al. , 2011; Ghazvinian et al. , 2014). However, to date, a standardised and accepted strategy to numerically model seismicity that successfully reproduces this behaviour for all cases does not exist.

ABSTRACT There are two missions for rock mechanics to accomplish in mining engineering: to destroy rock efficiently; to make rock structures safe. If these two missions are completed and mining operations are well managed, best mining results should be achieved. To accomplish the two missions, rock mechanics faces following challenges: how to make drilling, crushing and grinding more efficiently, in particular for grinding whose energy efficiency is less than 1%; how to make full use of explosive energy and destroy rock effectively; how to manage, reduce and finally predict seismic events and rock bursts; how to develop various mining methods; how to reduce borehole damage in deep mines or in the mines with high in-situ stresses; how to increase ore recovery and decrease dilution; how to improve mining safety; how to make rock support designs more scientifically. All these challenges will be analyzed in this paper. In addition, some topics such as rock mass classification, environment protection and the effects of loading rates, temperatures, and cyclic loading on mining engineering will be discussed. INTRODUCTION With an increasing population over the world, the demand on various raw materials has been increased for many years. According to OECD (2015), the amount of materials extracted worldwide doubled since 1980, reaching close to 72 Gt in 2010, and is projected to reach 100 Gt by 2030. On the other hand, a huge amount of raw materials has been lost during mining operation. Taking two common minerals, iron and gold, as examples, the production of iron ore and that of gold (final product in mines) were 3378 Mt and 3020 t in the year 2014 (Brown et al, 2016), respectively. Assuming that the average ore loss in mining is 10%, and the annual production for these materials is kept constant, the annual iron loss and gold loss in the world will be 375 Mt and 336 t, respectively. Obviously, mining industry has to reduce such a huge amount of ore loss in mining production. In addition, the industry needs to improve mining safety, reduce mining cost and decrease the damage to the environment. In order to realize these, rock mechanics plays an utmost important role.