Application of principle of fuzzy closeness optimization to classification of surrounding rock in tunnel

Several applicable methods of the stability classification of surrounding rock are discussed. Based on multi-factor taxonomy, the fuzzy theory is introduced into the classification. Because these factors have different effects on the final indices, they should be multiplied by different weighting coefficients. According to the grasped information on the geological conditions of surrounding rock, the concept of closeness and the principle of closeness optimization are introduced in to set up the fuzzy classification of rock mass so as to classify more exactly. An example is given to illustrate that the fuzzy classification is simple in computation, flexible in application and effective in practice.