Based on the uncertainty measurement theory

a uncertainty average clustering measurement model for tunnel surrounding rock classification was established. Due to the uncertain factors in judging the engineering quality of rock masses

seven indexes

i.e.

the rock grade

rock weathering degree

rock mass structure

elasticity longitudinalwave velocity of rock mass

influence degree of geological structure

development of joint fissure and ground water regime

were used as the discriminating factors. the indexes functions of unascertained measurement of 20 sets of rock samples were established

and the centre of the classification was indicated by using the average of classification of samples. The weight of indexes was calculated by entropy weight theory

and a prediction for the classification of residual tunnel surrounding rock was carried out using the rules of credible recognition. Each of the 20 sets of tunnel surrounding rockmass samples was tested according to the model

and the correctness rate is 100%. The other 10 sets of tunnel surrounding rock samples were predicted by using this model. The results show that the uncertainty measurement model classification agrees well with the actual measured ones. Therefore

it shows that the uncertaity measurement model is effective

available and can be applied to classification of tunnel surrounding rock in underground engineering. 