English to Arabic Science Geology

Analysis of Tunnel Related Testing
Cerchar Abrasion Test
The Cerchar Abrasion tests primary aim is to assess the abrasiveness of rock for mechanical excavation. Rock abrasiveness governs the performance of disc cutters, the rate of its replacement and therefore subsequent tunnel costs.
The test determines the abrasiveness of rock by of measuring the wear on the tip of a steel stylus brought on by scratching it against a freshly broken or cut rock surface for a set 10 mm distance. The steel stylus is assigned a Stylus Rockwell Hardness (HRC) of 55. A Cerchar Abrasivity Index (CAI) is assigned based on the wear applied to the steel stylus. Five individual tests are conducted on each sample and an average value is taken. The specimen is then classified based on this average value. The classification limits of the test are provided in Table 28.