Three-dimensional numerical blast damage analysis [Üç-boyutlu sayi{dotless}sal patlatma hasar analizi]

Yilmaz Ö. | Ünlü T.

Conference Object | 2013 | 23rd International Mining Congress and Exhibition of Turkey, IMCET 20131 , pp.61 - 74

In this study, the behaviour of rock mass subjected to blasting load is investigated using three dimensional finite difference numerical modelling. In the analyses, Mohr-Coulomb failure criterion has been used for the characterization of the rock mass strength. Stresses acting on the blasthole boundary have been simulated by an exponential function which reaches its maximum within a short time and then falls to zero value in a considerable period. The strain rate effect on the mechanical properties of rock material has also been taken into account in the analyses. Different explosive and site conditions have been studied to investig . . .ate the blasting damage. Results have shown that proposed equation for the dynamic compressive strength of rock material fits very well to general suggestions. Finally, it has been found that high density explosives are better at rock fragmentation in hard rock condition whereas low density explosives are better in relatively soft rock conditions Daha fazlası Daha az

Comparison of drillability and abrasivity properties of rocks [Kayaçlari{dotless}n delinebilirlik ve aşi{dotless}ndi{dotless}ri{dotless}ci{dotless}li{dotless}k özelliklerinin karşi{dotless}laşti{dotless}ri{dotless}lmasi{dotless}]

Çapik M. | Yilmaz A.O. | Yaşar S. | Yarali O. | Çavuşoglu I.

Conference Object | 2013 | 23rd International Mining Congress and Exhibition of Turkey, IMCET 20131 , pp.659 - 669

Drillability is defined as the penetration rate of a drill bit into the rock. Abrasion is broken off by the tools during the excavation of rocks. Different types of rock formations have different abrasiveness and hardness properties and that is significantly affected excavatability and drillability in the mechanical excavation systems. Because, abrasive rocks and hard rocks lead to an increase of the cost excavation, decrease of the penetration rate and atrophy of the cutter in a short time. This study was carried out in Hopa-Borcka (Artvin) Cankurtaran Highway Tunnel. Rock samples were obtained from Cankurtaran Tunnel at the changi . . .ng rock formations for the laboratory studies. The test samples were prepared at the appropriate size and quantity. Sievers J-miniature drill test (SJ) and the brittleness tests were carried out and for the drilling rate index values were calculated. Cerchar Abrasivity Index (CAI), Norway Abrasion Value (AV) and Bohme abrasion tests were carried out and for abrasiveness of rock properties. Uniaxial compressive strength, point load strength and Brazilian tensile strength tests were determined for the calculations mechanical properties of rock Daha fazlası Daha az

Determination of specific criteria about the ignition point temperatures and liability to spontaneous combustion of Zonguldak-Turkish hardcoal seams [zonguldak - Türkiye taşkömürlerinin tutuşma si{dotless}cakli{dotless}klari{dotless} ile ilgili özgün kriterlerin ve kendiliginden yanmaya yatki{dotless}nli{dotless}klari{dotless}ni{dotless}n belirlenmesi]

Baş F. | Erol D. | Didari V. | Öztürk M. | Salih B.

Conference Object | 2013 | 23rd International Mining Congress and Exhibition of Turkey, IMCET 20132 , pp.1187 - 1198

Most of coal seams are liable to spontaneous combustion in Zonguldak Hard Coal Basin. For more effective measures against fires in the mines, determination of spontaneous combustion characteristics and liability of coal seams to spontaneous combustion is very important. Therefore, ignition temperatures of hard coals have been determined by TGAMS system and crossing point technique together with the related specific criteria. Also characteristics of combustion are calculated from TGDTG thermograms. Also relationship between ignition temperatures and coal constituents are investigated. Tests are carried on the coal samples taken from . . .Kozlu (Çay, Haci{dotless}memiş, Kurul, Sulu), Üzülmez (Kurul, Piriç, Acun, Taban Aci{dotless}li{dotless}k), Amasra (Kali{dotless}n, Taşli{dotless}, Tavan) and Karadon (Sulu, Haci{dotless}memiş) Collieries of Turkish Hardcoal Enterprises Daha fazlası Daha az

The effects of using face bolt at shallow urban tunnels on the tunnel stability: Bornova metro case [Si{dotless}g şehir tünellerinde ayna çivisi kullani{dotless}mi{dotless}ni{dotless}n tünel durayli{dotless}li{dotless}gi{dotless}na etkisi: Bornova metro örnegi]

Küçük K. | Onargan T. | Aksoy C.O. | Geniş M.

Conference Object | 2013 | 23rd International Mining Congress and Exhibition of Turkey, IMCET 20132 , pp.1271 - 1281

Settlements during the driving of the tunnel is an important part of excavated tunneling process until the establishment of support and tunnels pre convergences due to the movement of the face into the tunnel. Therefore possible to reduce the amount of ground face to increase the stability of the tunnel. To this end, the face into the fiber columns, jet grout columns, face bolt, etc., can be performed. In this study, the tunnel excavation stage of permanent support with other support systems studied the effect of the face and applying face bolting case studies were evaluated with the use of the stability of the tunnel. The results c . . .learly demonstrated that the effect of the face bolts in the direction that prevents on the ground settlements Daha fazlası Daha az

Indirect estimation of cohesion in weak rocks [Zayi{dotless}f kayaçlarda kohezyonun dolayli{dotless} olarak tahmini]

Köken E.

Conference Object | 2013 | 23rd International Mining Congress and Exhibition of Turkey, IMCET 20131 , pp.537 - 547

Estimation of the geomechanical properties of weak rocks cannot usually be realized reliably due to the difficulties encountered in obtaining the core samples with proper dimensions and those encountered during the tests (i.e. disorder in the failure surfaces occurred, selection of the confining pressure in triaxial tests and crushing in core samples during the test). This situation is seen in uniaxial compression, triaxial compression and deformability tests in particular. In this study, several rock mechanics tests have been performed on thirteen different rock types (i.e. claystone, siltstone, travertine, sandstone, andesite, con . . .glomerate, tuff etc.) in order to indirect estimate the cohesion of weak rocks (?c<50MPa). In selection of the tests, special attention has been paid to ease of preparation of rock samples and selecting tests that are practically performable (i.e. indirect tensile strength test, P-wave velocity etc.). Besides, simple and multiple regression analysis have been conducted considering the weathering degree of the rocks used. The convenience of developed models has been verified by ?2 suitability test and it has been seen that the models are eligible. It was concluded that the cohesion of weak rocks could be estimated with sufficient reliability by the proposed empirical formulas Daha fazlası Daha az

Modeling of various degasification techniques: A case study from the amasra coal field, Turkey

Keles C. | Ripepi N. | Luxbacher K. | Karmis M. | Baris K. | Gurpinar S.

Conference Object | 2013 | 23rd International Mining Congress and Exhibition of Turkey, IMCET 20133 , pp.1673 - 1684

The Zonguldak hardcoal basin, located on the Western Black Sea coast of Turkey, is the only hard coal basin in the country. The seams in the area are extremely gassy and coal mines have experienced a number of methane outbursts and explosions that have caused loss of life and property. In addition to the safety risk, methane emissions from the existing mines in the basin are a significant source of greenhouse gases (GHG) and their reduction and control is a major environmental concern. Therefore, extraction of methane from the coal seams in the basin can be a solution to both carbon management and safety performance, providing at th . . .e same time a clean energy source for the country. Developing methane recovery technologies, before and/or during the mining cycle, requires sound engineering practices to realize the environmental and safety benefits. The aim of this study, sponsored by the United States Environmental Protection Agency (USEPA), is to investigate various options for the capture of coal mine methane in Zonguldak basin. The Amasra coal field, which is located in the eastern part of the basin, was chosen as the study area since there are mining activities in the region both by public and private sector companies. Hema Enerji A.S, a private company, has been developing a new underground coal mine in the region and the modeled coal seam in this study pertains to one of the panels under development by the company. The coal seam is at -420 m level and its thickness is around 4 m. An advanced general equation-of-state compositional simulator, Computer Modeling Group's GEM, was used to model methane capturing options, including pre-mining and mine level degasification techniques for methane recovery. The results will help to determine the most effective degasification techniques for this particular area Daha fazlası Daha az

Failure modes in shallow tunnels and galleries [Si{dotless}g tünellerde ve galerilerde yenilme türleri]

Sakiz U. | Gerçek H.

Conference Object | 2013 | 23rd International Mining Congress and Exhibition of Turkey, IMCET 20132 , pp.1259 - 1270

The stability of shallow tunnels and galleries is rather specific but an important area of interest in civil and mining engineering. In this study, failure modes occurring in circular tunnels excavated at shallow depths have been investigated. First, the concept of shallow tunnel was emphasized, and the factors that affect the stability of shallow underground openings were summarized. Then, the important failure modes observed in shallow tunnels were mentioned. Finally, in order to determine the failure geometries encountered in shallow tunnels, a series of parametric analyses were carried out by using a computer code that involved . . .two-dimensional finite element stress analysis. In the analyses, the effects of various combinations of in-situ stresses on the stability of a shallow circular tunnel were investigated. Different depths were considered for the tunnel located in a rock mass where the principal in-situ stresses varied with depth. For this purpose, the effects of in-situ stresses on the geometry of the region, occurring around the opening and having failure potential, were examined. An index (i.e., IOZ: index of overstressed zone) was used for comparing the relative sizes of overstressed regions obtained from various cases Daha fazlası Daha az

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