Taking a long sequence test data of physics and mechanics of cohesive surrounding rock as a base

the indices selection of surrounding rock classification was analyzed in a quantitative angle through mathematical statistics theory and grey-relation method. The research results show that the influential factors of mechanical indices are feasible to be basic classification indices. All preelection indices can be divided into three groups. On the ground of the results of grouping analysis and relation degree degree analysis

integration correlation coefficient of indices were calculated. Plastic index

natural density and liquid index have an important influence on cohesion and inner friction angle based on the value of integration correlation coefficient. The analysis results reveal liquid index

natural density and plastic index are the estimation indices of surrounding rock classification in cohensive soil tunnel.