Abstract: A method of distance discriminant analysis is used to classify the surrounding rock of highway tunnel. Based on experiences, several key factors, such as the uniaxial compressive strength σ_c , average spacing of joints d, values of rock quality RQD and groundwater condition, are selected to be parameters of discriminant analysis model. So a model of distance discriminant analysis is established though training a large set of surrounding rockmass samples which come from a series of tunnel projects. The discriminant results are validated and have a low misjudgment ratio. The results are also the same as the results from ANN method. Furthermore, the analysis result of the class Ⅳ for surrounding rock in selected parts of Fengshuling tunnel of Zhuyong highway in Zhejiang Province, which is calculated by the method of distance discriminant analysis, is in good agreement with standard method.

Key words: surrounding rock classification, distance discriminant analysis, misjudgment ratio, highway tunnel