Drilling geological strength index in altered gneiss

摘要

GSI is the methodology that developed by E. Hoek and other geologists throughout the world. It is particularly suitable for weathered and heterogeneous rock. However, there are not quantitative parameters for GSI, which leads to subjectivity when getting value. Based on the study of rock mass in the region where is abundant of gneiss during geotechnical investigation, the author propose a new parameter RCL; combined with geological effect of alteration which is very normal in metamorphic rock, the author try to use the photos of the intact core in the field to substitute the sketch of rock mass structure in the chart of GSI's value. Ultimately, a chart of GSI's value on the basis of gneiss was set up. In terms of the Contrast of elastic modulus between calculation and the value given by the unit of investigation, the author found that the result fit well, which means it is scientific of this chart.