This paper is divided into two parts. The first, engineering quality index of rock mass M to evaluate its quality is suggested. The second, a new classification system of rock masses is proposed on the basis of the concept of the fuzzy sets, because the uncertainty of physicomechanical parameters is characteristic of rocks.


Die vorliegende Arbeit besteht aus zwei Teilen. 1m ersten Teil wird der Qualitatsindex fuer den Gebirgskörper vorgeschlagen, urn dessen Qualitat zu beurteilen. Im zweiten Teil wird ein neues Klassifizierungssystem auf der Basis der Fuzzy-Mathematik aufgestellt, da die physikalischen und mechanischen Parameter des Gesteins eine unbestimmte Charakteristik besitzen.


L''article est divise en deux parties. La premiere partie, nous suggerons que la qualite de roche massive soit evaluee par le qualitatif index M des travaux aux roches massives. La deuxieme partie, un nouveau systeme de classification de roches massives est propose base sur la notion de la fuzzy-mathematiques parce que l''incertitude des parametres physicomechaniques est une caracteristique des roches.


There are two conditions in the underground construction: the first, it is carried out construction under given conditions, for which there are geological factors of all kinds and under the necessity of doing engineering treatment for unhealthy geological factors, the second, it is engineering site of underground construction which is selected, therefore, there is a problem of quantitative evaluation of quality for rock masses. This condition is discussed in this paper.

But this problem is associated with excavation of dam foundations also. This is a important problem, because it involve the limit of t i me of construction which is also a problem of economy. In fact, the more cubic metres of rock to be excavated, the larger the filled concrete volume and the larger the limit of time of construction will be, on the other hand, the depth of excavation depends also upon the strength, deformation and stnbi lity of the rock masses.


Engineering quality of rock mass depends on weathered, fractured and conditions of ground water et al, Yang Zi-wen (1980) Suggested by "Engineering Quality Index of Rock Mass M" to express its quality:

(Equation in full paper)


Another approach to engineering comprehensive evaluation for rock masses is method of fuzzy sets (MFS) which was proposed by Tao Zhen-yu and Peng Zu-zeng (1981) and is based on the concept of the fuzzy sets (Zadeh, L. A, J956), because the uncertainty of physicomechanical parameters is characteristic of rocks.

This paper is with the purpose that w a shall be to improve and make further ex pl o na t io ns of MFS.

Any classification is always based on the evaluations of every single factor such as uniaxial compressive strength, velocity of longitudinal wave et al, which are obtained from investigations and measurements. Perhaps, these factors are more or less the same, but they can be basically divided into two groups, The first grpup of parameters of rock masses can be symbolized through real mumbers of certain interval [a, b], it is called interval parameter.

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