Evaluation of Surrounding Rock Quality of Tunnels Using a Combined Method of Weighted Norms Based Grey Relational Analysis and Fuzzy Mathematics Theory

摘要

To investigate surrounding rock quality (SRQ) of the tunnels subjected to design and construction processes, this research employed a weighted norms based fuzzy comprehensive evaluation (WN-FCE) method by integrating weighted norms based grey relational analysis and fuzzy mathematics theory. Furthermore, this study established a membership function between each of evaluating indexes and the grade of surrounding rocks to obtain evaluated matrix of a single factor, and derived the weights of each of the indexes by introducing weighted norms based grey relation. On these bases, the fuzzy sets could be obtained based on the WN-FCE approach and it was further used for the evaluation of SRQ of tunnels. The saturated uniaxial compressive strength R-c of rocks, RQD value of SRQ index, friction coefficient J(f) of structural planes, joint spacing J(d), groundwater state W, and intactness index K-v of rock masses were used as the evaluating indexes to comprehensively evaluate the SRQ. The evaluation results were in agreement with those obtained by using the evaluation method based on extension theory and the root-mean-square residual (RMR) method. This indicates that the WN-FCE method is able to accurately reflect the grade of surrounding rocks of tunnels.