Abstract Inspired by the flysch which was given by Hoek in RocLab software and based on the field work and lab experiment,a quantitative diagram of the geological strength index(GSI) for granite based on mineral structure and drilling is established;of which the process is as follows:(1) Mineral structure,rock core length and joint condition of rock are introduced in this diagram to help the quantitative study of GSI. (2) Try to use the typical picture of field core to substitute the sketch drawing given by Hoek. Combining with characteristics such as rock quality designation of core,core recovery ratio and rock structure and so on,the pictures are described. According to Hoek-Brown formula,elastic modulus E of granite is calculated by the proposed diagram of GSI. Comparison between the calculated result and that given by the exploration firm is conducted;it is also shown that the results fit each other very well and the minimum error of E between them is 0.11 GPa. Therefore,the new GSI diagram is scientific and it can be widely used in drilling engineering to estimate the parameters of granite.
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Received: 12 November 2010
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