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Yao X.-H.,NJU ECE Institute for Underground and Geo environment | Zhao X.-B.,NJU ECE Institute for Underground and Geo environment | Gong Q.-M.,Beijing University of Technology | Ma H.-S.,Beijing Research Institute of Uranium Geology | And 4 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

In order to study the crack modes of Beishan granite under the indentation of a single disc rolling cutter, a series of linear cutting experiments are conducted on the Mechanical Rock Fragmentation Experimental Platform developed by Beijing University of Technology. During the experiment, a constant cross-section disc cutter with a diameter of 17 inches (432 mm) is used and a block of Beishan granite with the size of 1000×1000×600 mm is adopted. After the tests, it is found that there is a cracked part beneath the groove with varied fragmentation degree. Based on the observed crack mode and crack density, the rock sample is classified into re-compacted zone, crushed and cracked zone and intact rock zone, then the sizes and areas of these zones are summarized accordingly. Meanwhile the ultrasonic velocity tests and rebound tests are conducted to obtain the properties of different zones. Finally, it is found that these test results agree well with the fragmentation degrees of different zones. In addition, as the time of cutting increases, the areas of these zones expand significantly, while the properties of the corresponding zones almost keep constant. Source


Guo L.,Nanjing University | Guo L.,NJU ECE Institute for Underground and Geo environment | Li X.-Z.,Nanjing University | Li X.-Z.,NJU ECE Institute for Underground and Geo environment | And 5 more authors.
ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 | Year: 2014

The accuracy of seepage calculations in rock mass is directly influenced by the confidence level of the corresponding discontinuities network models. For the purpose of more efficient application of the stochastic discontinuities model, improvements of efficiency, both in-situ measurements and subsequent statistical analyses with respect to the discontinuities parameters are needed. New digital techniques, e.g. GPS (Global Positioning System) and GIS (Geographical Information System), are applied to the in-situ measurements and data processing of discontinuities parameters. Confidence level of the new model is significantly augmented compared with the accuracy and sampling quantity of the less efficient and more labor-intensive traditional in-situ measurements. Over 10,000 discontinuities were measured using GPS in Chinese high-level radioactive waste repository candidate site in Beishan. The three-dimensional stochastic discontinuities network model is established based upon the statistical analyses of the digitalized samples. The accuracy of the model is graphically and numerically validated. Results suggest that higher accuracy of the stochastic model is obtained based on the proposed digital techniques, and the requirement of engineering application is better fulfilled. © 2014 by Japanese Committee for Rock Mechanics. Source


Guo L.,Nanjing University | Guo L.,NJU ECE Institute for Underground and Geo environment | Li X.,Nanjing University | Li X.,NJU ECE Institute for Underground and Geo environment | And 6 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2015

The confidence level of seepage calculations in rock mass is directly influenced by the reliability of corresponding discontinuities network models. A detailed investigation on rock mass discontinuities was launched into the well outcropped granite body in Chinese high-level radioactive waste repository candidate site in Beishan of Gansu province using new digital techniques, such as GPS(global positioning system) and GIS(geographical information system). And the three-dimensional random discontinuities network model was established after the digital statistics processing of over 10 000 discontinuities acquired in the investigation. At last, the accuracy of the model was graphically and numerically validated. The results show that compared with the traditional method, the digital measurement processing means can overcome the insufficiency of statistical sample size and precision, and can complete the detailed investigation of regional rock mass discontinuities very well. And the random model with ideal test effect is more suitable for numerically simulated calculations of mechanical properties and seepage. ©, 2015, Academia Sinica. All right reserved. Source

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