International Journal of Rock Mechanics & Mining Sciences 44 (2007) 468–476 Technical note Correlative study of linear small and full-scale rock cutting tests to select mechanized excavation machines C. Balci à , N. Bilgin Mining Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey Received 3 May 2006; received in revised form 13 July 2006; accepted 2 September 2006 Available online 27 November 2006 Keywords: Full-scale rock cutting; Small-scale rock cutting; Mechanical excavation; Performance prediction; Specific energy; Mechanical properties of rocks 1. Introduction Application of mechanical excavators for rock excava- tion in both civil construction and mining engineering fields has increased significantly in recent years, and small-scale (core cutting) and full-scale laboratory rock cutting tests have emerged as necessities to provide basic data for machine selection, design and performance prediction for a given rock formation [1–5]. The force data obtained from the two tests are used as input for selection and design of an excavator, selection of cutter, definition of optimum cutting geometry and prediction of mechanical excavators’ performance and cost. Prediction of the excavation performance of any mechanical excavator such as roadheaders, continuous miners and shearers for any geological formation is one of the main concerns in determining the economics of a mechanized mining and/or tunneling operation. There are several methods of performance prediction and the best approach may be the use of more than one of these methods. These methods may be generally classified as the full-scale linear cutting test, the small-scale cutting test (core cutting), empirical approach, semi-theoretical ap- proach and field trial of a real machine [6–10]. The full-scale linear cutting test is widely accepted and a precise approach, since a large block of rock in size of (1  1  0.6 m) is cut in the laboratory with an industrial cutter. The cutting force, normal force, sideways force and specific energy values are obtained for different cutter spacings and depths of cutting. Production rate of a mechanical miner is calculated based on the optimum specific energy or using a computer model/simulation requiring forces acting on the cutters. The basic disadvan- tage of the full-scale rock-cutting test is that it requires large blocks of rock samples, which are usually difficult, too expensive, or impossible to obtain. Furthermore, this type of testing equipment is found in only a few research centers in the world [11,12]. Therefore, the core or rectangular block rock sample based cuttability tests are preferred in many cases, even though their predictive abilities are lower than the full-scale rock cutting tests. The small-scale cutting test (core cutting) is discussed in detail by McFeat and Fowell [12–14]. The test results are classified as index values and evaluated according to previously accumulated field performance data. The basic disadvantage of this test is that the predictions using this method are based on an index cutter instead of a real life cutter. In addition, the database is based only on the field performance of light and medium weight Dosco road- headers used in coal mines in England. Specific energy values were correlated, in the past, with rock properties by different researchers [13,14,15–18]. Fowell and McFeat-Smith [12–14] performed experimental studies to correlate specific energy obtained by the small- scale rock cutting tests to some rock properties such as cone indenter index, cementation coefficient, Schmidt hammer rebound value and compressive strength. Balci and Bilgin [15,16] searched relationships between optimum specific energy obtained by the full-scale cutting tests and different rock properties such as compressive strength, tensile strength, static and dynamic elasticity moduli. Copur et al. [17,18] searched for relations between optimum specific energy obtained by the full-scale cutting ARTICLE IN PRESS www.elsevier.com/locate/ijrmms 1365-1609/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijrmms.2006.09.001 à Corresponding author. Tel.: +90 212 285 6138; fax: +90 212 285 6131. E-mail address: cemalb@itu.edu.tr (C. Balci).