Abstract

In this study, the effects of textural properties of grains such as aspect ratio, roundness, and diameter on the LCPC abrasivity coefficient (LAC) were investigated for six different coarse-grained igneous rocks. The LAC was correlated to the abrasive mineral contents (AMC) and a good correlation was found between the two parameters. Then, the LAC was correlated to the AMC multiplied by the textural properties of grains, respectively. Compared to the correlation coefficient of the relation between the LAC and the AMC, correlation coefficient was increased by including the textural properties of grains to the correlation. A combined parameter called shape and size coefficient (SSC) was also defined. The correlation coefficient of the relation between the LAC and the AMC multiplied by the SSC is fairly higher than that of the previous correlations derived. Concluding remark is that the textural properties of loosened materials have a strong influence on tool wear.

1 Introduction
1.1 About the Brenner Base Tunnel

The rock abrasivity may highly influence the cost and schedule of the excavation projects performed in rock mass. If the rock is abrasive, in addition to the high cost due to cutting tool wear, the replacement of tools causes considerable downtimes. On the other hand, in the abrasive grounds, wear can also occur on the several parts of tunnel boring machine (TBM) such as front, rear and periphery of the cutterhead structure, bulkhead and plunging wall structures, and outlet devices (Nilsen et al. 2006 & 2007). The development of predictive models for the wear of cutting tools and various machine components is necessary for the planning and cost estimation of projects.

The aim of this study is to investigate the effects of aspect ratio, roundness and diameters of grains on the LCPC abrasivity coefficient (LAC) for coarse-grained igneous rocks. The approaches used for the determination of roundness and aspect ratio describing the elongation of blocks are different from that of the previous studies.

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