The classification of rock mass around tunnel and underground chamber for water conservancy and hydroelectric engineering

In this paper,the usual methods and main problems of surrounding rock mass classification for water conservancy and hydroelectric engineering in China are introduced,the future development of surrounding rock mass classification is looked ahead,and the correlations between Q-value and other ratings are given.It is pointed out that the classification of surroundjng rock mass in the conditions of high crustal stress and high external water pressure is needed to be modified.The relations between the rating of surrounding rock mass and rock burst of hard rocks,plastic deformation of soft rocks are not known clearly.