Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
A Look At The Effect Of Scale On The Shear Evaluation Of Rock Joints
Pasamehmetoglu, A.G. (Mining Engineering Department, Middle East Technical University) | Ozgenoglu, A. (Mining Engineering Department, Middle East Technical University) | Bolukbasi, N. (Mining Engineering Department, Middle East Technical University) | Karpuz, C. (Mining Engineering Department, Middle East Technical University) | Bilgin, A. (Mining Engineering Department, Middle East Technical University) | Can, C. (Mining Engineering Department, Middle East Technical University)
SYNOPSIS: The potential influence of joint test-size on measurements if shear strength has often been pointed out and recent experimental studies have shown that there are significant scale effects on both the shear strength and deformation characteristics, especially in the case of rough, undulating joint types. In this paper, in-situ shear tests, conducted at Sir Dam Site, K. Maraş, Turkey, together with small scale shear tests on cores recovered from the same location are explained. Three large-scale and several small scale shear tests are carried out. Blocks 70x70x35 em are cut in quartite which is traversed by inclined bedding planes containing filling material. For small-scale tests a portable shear box is employed. The results of both types of test are analysed and the conclusions drawn are given. RESUME: On a souvent releve l' influence possible du facteur "echelle" dans les essais de resistance au cisaillement, et des etudes recentes montrent son effet important, dans de tels essais, sur la determination des caracteristiques de resistance au cisaillement ainsi que sur celles de la deformation, surtout dans le cas des joints rugueux et accidentes. Cette communication examine les resultats d'essais de cisaillement effectues au chantier du barrage Sir K. Maraş, en Turquie, ainsi que d'essais à petite echelle effectues sur des carottes preleves au même site. Trois essais à grande echelle et plusieurs essais à petite echelle ont ete realises. Des blocs de 70x70x35 cm ont ete decoupes dans du quartzite traverse par des plans de stratification inclines contenant du materiau de remplissage. Pour les essais à petite echelle on a utilise une boîte à essais de cisaillement portative. On donne les resultats obtenus pour les deux types d'essai ainsi que les conclusions qu'on en tire. ZUSAMMENFASSUNG: Die potenziellen Einfluesse des Klufttest-Formats an den Scherfestigkeitsmessungen sind oft hervorgehoben worden, und experimentelle Untersuchungen haben kuerzlich gezeigt, daß es besonders im Falle der rauhen und unebenen Kluftarten bedeutende Maßstabeinfluesse an der Scherfestigkeit und dem Deformationsverhalten gibt. In der vorliegenden Arbeit werden die am Sir Staudamm bei K. Maraş (Tuerkei) durchgefuehrten Versuche, sowie die unter Verwendung von kleinen Maßstaben an den an gleicher Stelle entnommenen Kernen durchgefuehrten Scherungstests dargestellt. Insgesamt sind drei großmaßstabliche und mehrere kleinformatige Scherversuche durchgefuehrt worden. Blöcke von 70x70x35 em wurden aus Quarzit herausgeschnitten, der von geneigten und Fuellungsmaterial enthaltenden Schichtungsebenen durchsetzt war. Bei den kleinformatigen Versuchen sind tragbare Scherapparate verwendet worden. Die Resultate der beiden Versuchstypen wurden analysiert, und die daraus abgeleiteten Schlußfolgerungen sind beigefuegt. INTRODUCTION The behaviour of rock masses is generally controlled by discontinuities in the rock mass. Determination of the shear properties of the discontinuities relevant to stability analysis may vary from a large scale test to small scale laboratory direct shear test. Small scale samples usually represent only a fraction of the natural joint exposures and tests on these samples sometimes yield unrepresentative data. But they are cheap and easy to carry out.; when it is compared to insitu tests. So, as - Wareham and Sherwood (1974) pointed out, the choice of an appropriate joint test-size is generally based on both economic-and technical considerations. The existing data in the literature from small and large scale tests are extremely limited and often inconclusive. Londe (1972) compared the results of small scale laboratory tests with large scale field tests and reported a good agreement between the residual friction angles found by both methods. Pratt, et. ale (1974) carried out a series of field and laboratory tests on a range of joint sizes in a weathered quartz diorite and showed that the peak shear strength of natural joints decreased by 40% as the sample areas increased from 142 to 5130 cm. Bandis, et. al (1981) performed tests on different sized and types joint surface replicas obtained by using moulding technique and gave detailed experimental evidence to the positive scale effect as Pratt, et. al (1974). Scale effects are more pronounced in the case of rough, undulating joint types, whereas they are virtually absent for planar joints. Bandis, et. al (1981) also stated that-negative scale effect met in the literature is due to dissimilar roughness on the small and large scale joints. On the other hand, in the case of filled joints, as Bandis, et. al (1981) pointed out no scale effect is to be expected in the cases with a thickness of filling larger than the roughness amplitude. In this work, shear characteristics of planar to slightly undulated bedding planes with filling material of 0–30 mm thickness are examined with large and small scale tests. TEST SITE AND TESTING PROCEDURE This study has been carried out as a part of the geotechnical investigations at Sir dam site of the hydroelectric power plant of Berke project, in K.Maraş, Turkey. Sir dam site, on Ceyhan river, at 32 km. southwest of K.Maraş is located on regularly dipping hard and fractured metaquartzite.
- Geology > Geological Subdiscipline > Geomechanics (0.51)
- Geology > Mineral > Silicate (0.35)
- Energy > Oil & Gas > Upstream (0.80)
- Energy > Power Industry (0.54)
An Investigation Into The Rock Mechanics Aspects Of Sublevel Open Stope Mining
Pasamehmetoglu, A.G. (Mining Engineering Department, Middle East Technical University) | Irfan, T.Y. (Mining Engineering Department, Middle East Technical University) | Bolukbasi, N. (Mining Engineering Department, Middle East Technical University) | Bilgin, A. (Mining Engineering Department, Middle East Technical University) | Ozgenoglu, A. (Mining Engineering Department, Middle East Technical University) | Karpuz, C. (Mining Engineering Department, Middle East Technical University)
SYNOPSIS: Rock mechanics investigations are carried out to evaluate the sublevel open stope mining method used at the tungsten mine in Bursa (Turkey) with respect to the stability of stopes, rib pillars and its various galleries. Although the orebody is massive in nature, it shows various rock mass strength characteristics. Major geological patterns and their strength characteristics are extensively studied together with the physical and mechanical properties of the ore-bearing rock (scarn) and the wall rocks. Using different rock mass classification systems, a careful evaluation of rock mass is established. Back analyses are carried out. The stability of stopes and pillars is studied. Design procedures and measures to be taken are suggested. RESUME: Des recherches en mecaniqe de roches ont ete faites pour evaluer la methode d'exploitation par chambres à sous etage employee a la mine de Wolfram à Bursa-Uluda, du point de vue de la stabilite des chantiers de travail, des piliers et des galeries. Bienque la formation soit massive, elle montre des resistances mecaniques differentes. Ses principaux aspects geologiques ainsi que ses resistances caracteristiques ont ete largement etudiees. De même les proprietes physiques et mecaniques de la roche contenant le minerai (skarn) et les roches formant le toit et le mur ont ete bien etudiees. En utilisant de differents systèmes de classification des roches massives, une evaluation soigneuse des roches a ete etablie. Une analyse ulterieure a ete effectuee. Des procedes pour la realisation du projet et les precautions à prendre ont ete suggeres. ZUSAMMENFASSUNG: Felsmechanische Untersuchungen werden durchgefuehrt, um den im Wolfram-Bergbau in Bursa (Tuerkei) angewandten Abbau mit Teilsohlenstrecken hinsichtlich der Stabilitat der Kammern, des Langfrontabbaupfeilers und der diversen Strecken auszuwerten. Obwohl das Erz in der Natur als massiver Körper auf tritt, zeigt das Gebirge verschiedene Festigkeitseigenschaften. Die geologischen Hauptformen und ihre Festigkeitseigenheiten sowie die physikalischen und mechanischen Eigenschaften des erzfuehrenden Gesteins (skarn) und des Nebengesteins wurden ausfuehrlich untersucht. Eine sorgfaltige Auswertung des Gebirges unter Verwendung verschiedener Gebirgsklassifizierungssysteme wurde unternommen und Rueckanalysen wurden durchgefuehrt. Die Stabilitat von Kammern und Pfeilern wurde untersucht. Entwurfsprozeduren und Sicherheitsmaßnahmen werden vorgeschlagen. 1. INTRODUCTION Uludağ tungsten deposits in Bursa, Turkey are located over 2100 meters near the peak of Uludağ Mountain and have been exploited by open pit and underground mining. Primary underground production comes from sublevel open stopes of full orebody height, which will subsequently be filled to aid pillar recovery (Fig.l). At present production from three primary sublevel open stopes is completed and at the fourth one it-is near to completion. The stopes and pillars between them are 15 meters in width. The height and length of the stopes are approximately 30 meters and 100 meters respectively. The first part of continuing rock mechanics research initiated at this mine concerns with the re-evaluation of the sublevel open stope mining method with respect to stability of stopes, rib pillars and its various galleries and drifts. Here, outcome of first part of this extensive rock mechanics investigations will be presented. 2. GEOLOGY OF TUNGSTEN DEPOSITS 2.1 Geological setting Uludağ tungsten mine is geologically situated in the scarn rocks between marbles of Paleozoic-aged Metamorphic Series and the younger granodioritic batholith. The Metamorphic Series which include amphibolites, gneisses and marbles at the base with mica-schists, phyllites and semi-marbles,at the top, and the overlying Permian-Carboniferous, limestones and clastic rocks,have been folded into a gigantic anticline during the Alpine orogeny accompanied by the intrusion of a batholith (Ketin 1947, P1nar-Lahn 1954, Ronner 1954, Kaaden 1958, Öztunall 1967). Continued tectonism and vertical uplift has subjected the Uludağ massif to intense weathering and erosion in Neogene and Recent times resulting in the exposure of granodiorite, marble and ore-bearing scarn in the vicinity of the summit region (Inan 1979). Tunsten bearing minerals are mainly found in scarn which is formed from marbles by the contact metamorphism of granodioritc intrusion. Two types of scarn have been recognized (Inan 1979):Endoscarn is formed as a thin band within the magmatic mass of the contact zone and represents metasomatically altered granodiorite ("granitic scarn'). Exoscarn is formed within the marbles by contact metamorphism process and is generally dark green or reddish brown (garnet rich) in color with clinopyroxene, garnet, quartz, epidote and calcite as the main constituents. It also contains scheelite, wolframite, chlorite, tremolite, pyrite, chalcopyrite, fluorite, sphalerite, magnetite, hematite, molibdenite and bismuthite (Kaaden 1954). Marbles are white, coarsely crystalline, jointed tand contain relict bedding structures. These rocks are poor in ore and tungsten-bearing scheelite mineral is only present in thin vein formations. Granodiorite is a grey, medium-grained biotite-rich rock with plagioclase (40–45%), al- kali feldspar (1315%), quartz, biotite and muscovite as the main constituents. 2.2 Scarn formation and mineralization Uludağ scarn belt is formed by the intrusion of granodioritic batholith into Palaeozoic metamorphic rocks and subsequent contact metamorphic of the marbles under the control of regional structural elements.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.68)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.54)
- (3 more...)